Alternative Design 2 - Biomedical Engineering
Contents
1. As blood begins flowing through the brachial artery again it will cause small pulsations that will be picked up by the pressure sensor in the cuff Fig 15 This waveform will be analyzed by the microprocessor to determine the systolic and diastolic pressures Time seconds Figure 15 Blood Pressure Waveform Picked Up by Pressure Sensor 17 A threshold voltage level will be set This will be done by experimentally comparing blood pressure readings from a sphygmometer or other commercial device to those detected by our pressure sensor Once 4 pulsations peak above the threshold level the voltage will be recorded and from that value the systolic pressure determined The microprocessor will continue to monitor the blood pressure readings and diastolic pressure will be taken when the voltage drops below the threshold voltage for 2 pulsations After the diastolic pressure is determined a command from the microprocessor will deflate the cuff quickly and completely 14 Systole pressure detected Figure 16 Block Diagram of Automatic Blood Pressure Measuring System Due to the safety issues that arise with automatic blood pressure systems we have incorporated a kill switch into our design Fig 16 17 If at any time during the blood pressure measurement the user wants to stop the inflation of the cuff and rapidly deflate it they just need to press the vital signs monitor On Off button This will cut power to the who2. When designing this project we found it rather important to include two different types of power The device will mainly be run from an external power source by using a power cord It will also be equipped with rechargeable backup batteries in case of a power failure Fig 27 For the power supply we plan on using a very generic universal power cord which will plug into the back of our device and then also plug into the wall This cord will only fit into the socket designated for it on the device to prevent any accidental power surge or electrocution For the backup power supply we determined the best way would be to use nickel cadmium rechargeable batteries Although lead acid batteries can sometimes produce more voltage nickel cadmium batteries are safer and will recharge a lot quicker The need for a backup battery is so the patient can take signs even if the power is gone Also if power is lost that means the alarm will also be shut off causing the patient to possibly miss a time This could be life threatening to some patients so we felt it was very important to include a backup supply Figure 27 Image of rechargeable battery 24 1 2 12 USB Port The USB device is a very important part to include in this project The main job of the USB device is to store the readings taken by the machine This device will then be connected to a computer in which it is possible to send the readings to any computer that has an internet connection The USB
3. R is the resistance in ohms and a b and c are constants called the Steinhart Hart parameters This output can be linearized through the use of a Wheatstone bridge Fig 4 THERMIS TOR RTI VozW1 V2 Differential Amp Figure 4 Thermistor Linearizing Circuit Thus the resistance of the thermistor RT1 can be modeled by the first order equation R T RII aT where R is the resistance of the other resistance in the Wheatstone bridge a is the temperature coefficient and AT is the change in temperature from the reference temperature AT T T in degrees Kelvin The reference temperature T o of the thermistor is given by the manufacturer and for medical thermistors it is usually around 300 K The temperature coefficient a can be calculated from the following equation d R T dT _ 9 R T T where f is a temperature constant typically around 4000 K 8 The value of the resistors R used to linearize the thermistor will be determined from the reference temperature and other values given by the manufacturer p or a using the above equations For our use as an oral temperature probe the thermistor needs to be linearized calibrated around 98 6 F 37 C for a temperature range of at least 90 104 F 32 40 C When linearizing the thermistor we must be careful to keep the accuracy of the thermometer high 1 C so as to be able to take appropriate measurements After being linearized the signal will be s
4. anyone with vision or hearing impairment Also the simple user interface of the device allows it to be used by individuals of all ages and technological savvy This leads into sustainability Our device was designed with its ability for future and continued use in mind Not only must the device be designed so that it can last and function properly for years but it also needs to use up to date parts and technology so that it does not become outmoded An example of this was the selection of the rechargeable battery for our device In many vital signs monitors being used rechargeable lead batteries power the device However lead materials are currently being phased out of medical devices so we chose to use a nickel cadmium rechargeable battery in our design This is one step that was taken to ensure that our device will still be acceptable for use years from now Because this is a medical device and will have direct contact with our clients client patient safety was an important constraint in our design process All circuits and power sources must be properly grounded to prevent accidental electrocution and safety measures had to be put in place to prevent an injury use of the device might cause Since 26 this is a medical monitoring device one of its safety constraints is that it should be explosion proof It should spark or create flames to prevent explosion used in the presence of pure oxygen Most components of our design are relatively benign
5. fact that we are going to input and output the data like a microcontroller but use the digital signal processing features to analyze and filter the signals FIR and IIR filters The Blackfin will function like the traditional microcontroller taking the electric signals from the transducer passing them through an analog to digital converter and processing the information Like the PIC microcontrollers the Blackfin contains an internal analog to digital converter There are many advantages for us in using digital signal processing rather than traditional 100 microcontroller functions Microcontrollers can be cheap and easy to assemble but are difficult to calibrate and modify Using DSP one can more easily design and modify their work due to the fact that it is all computer based Thus one can rely on their software based filters much more DSPs are also much faster than microcontrollers A typical PIC microcontroller has a clock speed of about 20 MHz whereas the Blackfin has a clock speed of 350 MHz Table 2 We will use the PF pins I O ports on microcontrollers on the Blackfin to function as inputs for the transducers and outputs for the LCD screens and speaker Due to the Blackfin s abilities it should be the only microprocessor we need for our device We also chose to use the Blackfin due it its versatility in programming code The Blackfin can take C C code as well as LabVIEW Vi s Since we have had more experience using LabVIEW w
6. gt 3 Chua C S and Siew Mun Hin Digital Blood Pressure Meter Freescale Semiconductor May 2005 lt http www freescale com files sensors doc app_note AN1571 pdf gt 4 DeMarre Dean A and David Michaels Bioelectronic Measurements New Jersey Prentice Hall Inc 1983 5 Getting Started with Blackfin Processors Analog Devices 2006 lt http www analog com gt 6 Lineared NTC Thermistor eCircuit Center 2002 lt http www ecircuitcenter com Circuits therm_ckt1 therm_ckt1 htm gt 7 MLT 1132 Piezo respiratory Belt Transducer Data Sheet AD Instruments 2006 lt http www adinstruments com products generate_pdf generate_pdf php code MLT1132 gt 8 Northrop Robert B Noninvasive Instrumentation and Measurements in Medical Diagnosis New York CRC Press 2002 9 Number of current home health care patients by type of aids devices used sex and race United States 2000 Current Home Care Patients Feb 2004 lt http www cdc gov nchs data nhhesd curhomecare00 pdf 32 10 PIC16F877 Data Sheet Microchip Technology 2001 lt http ww1 microchip com downloads en DeviceDoc 30292c pdf gt 11 Piezoelectricity Wikipedia the Free Encyclopedia 2006 lt http en wikipedia org wiki Piezo_electricity gt 12 SpeakJet User s Manual Magnivation 2004 lt http www speechchips com downloads speakjetusermanual pdf gt 13 Safe Circuit D
7. maintenance We learned to integrate microcontroller based data gathering with digital signal processing to achieve a cheaper more efficient way of data analysis Also the text to speech function in our design was a new and exciting function to learn about Since none of us have ever worked with such a unique and advanced tool it made the research enjoyable and informative There are many devices out there used for speech synthesis but we needed to find the one that would be compatible with the microcontroller we selected as well as capable of converting the text output from the microcontroller to sound Most algorithms associated with speech chips cannot convert English text straight to audio which is why we integrated the TTS256 Text to Code microcontroller to convert text to phonetics which is compatible with the SpeakJet Through designing the thermometer for the accessible vital signs monitor we have learned about the Steinhart Hart equation and the properties of thermistors It is important to realize that thermistors behave nonlinearly and to understand what effects this has on designing a thermometer In order to use the thermistor output it must be linearized This can be done over a small temperature range but any readings outside the temperature range will be increasingly inaccurate the farther away they are This means that one should only use an oral thermometer to measure oral body temperature not air temperature or a cold beverag
8. provided that basic electrical safety is followed but a major point of health and safety constraint was the design and incorporation of the automatic blood pressure measuring device Self inflating blood pressure cuffs can cause injury if not properly calibrated and used Fig 29 Figure 29 Bruising caused by one use of an automatic blood pressure cuff 14 Bruising can result if the cuff inflates too much Pain and circulation cutoff can occur if the cuff does not deflate and at the extreme this could lead to tissue death Our accessible vitals signs monitoring system has really no political constraints but it does have social and privacy constraints Part of our system includes the transmission of vitals signs of the internet to a health care provider To protect patient privacy and abide by the Health Insurance Portability and Accountability Act HIPAA the transmission of vital signs will be done via a secure password protected website This will protect our clients personal information while still giving them flexibility in the transmission of their vital signs to their physicians or HMOs This is an important and valid constraint in our device design The internet provides rapid transfer of information but it is filled with predators and opportunists who like to access the private information of others It is important for us to protect our clients when they are contacting their physicians so that their medical information does not
9. the hot side of the power system touches the side of a casing there is no danger to the user of the monitor The inner part of the monitor should be designed so that neither the hot or neutral part of the power cord touches the casing but if the hot wire does accidentally touch the casing then this could be dangerous If the casing is conductive and the hot wire touches the side of the case then the case will be made electrically common to the wire and touching the case will be just as hazardous as touching the wire bare In addition it is always important for an electrical design to have a solid connection to earth ground A power system with no secure connection to earth ground could pose a safety hazard There is no way to guarantee how much or how little voltage will exist between any point in the circuit and earth ground By grounding one side of the power system s voltage source at least one point in the circuit can be assured to present no shock hazard One way to ensure proper ground is to use a three prong plug The third prong on the power cord provides a direct electrical connection from the appliance case to earth ground making the two points electrically common with each other If they re electrically common then there cannot be any voltage dropped between them Even if the hot wire accidentally touches the metal casing it will create a direct short circuit back to the voltage source through the ground
10. wire Choosing the correct gauge wire is also an important factor to consider An electrical hazard exists when the wire is too small a gauge for the current it will carry If a wire is too small for the current it is supposed to carry the wire will heat up The heated wire could have the potential to cause a fire inside the monitor After selecting the correct wire gauge it is important to make sure that all wires are properly insulated and cleanly soldered to its respective position on the circuit board Frayed wires have the potential to interact with other wires causing the monitor to not work properly or cause a fire In addition to the electrical safety issues it was also made sure that the operator of the monitor does no harm to the patient while taking measurements Each instrument used to obtain measurements was carefully chosen to be as simple and safe as possible Out of the four vital signs being obtained the only one which needs skill to operate 28 would be blood pressure Using the blood pressure cuff incorrectly could not only cause the monitor to record the wrong vital signs but also harm the patient Squeezing the blood pressure cuff too tightly could injure the patient To minimize this potential hazard we will use an automatic blood pressure cuff allowing the person who is taking the readings to have no prior skill Since the people taking the vital sign readings are elderly or young the automatic blood pressure cuff makes
11. 25 000 Eniurad Dae Gy nooo ayn win esa wore mti 30 700 7 Intravenous therapy 2 6 ee een 52 300 E 17 100 a i Diygan isses ronde ri S URCR SC a RS CR RUE 8 114 600 18 200 25 700 43 400 19 900 Other respiratory therapy 2 2 0 00020000 45 300 15 000 s Otheraids llus 187 500 11 600 23 600 33 100 28 200 58 600 32 400 Figure does not meet standard of reliability or precision because the sample size is less than 30 if shown without an estimate If shown with an estimate the sample size is between 30 and 59 or the sample size is greater than 59 but has a relative standard error of 30 percent or more Quantity zero Age is the patient s age at the time of survey Numbers will not add to totals because a patient may be included in more than one category Total number of home health care patients includes manual and motorized wheelchairs Includes geri chairs lift chairs and other specialized chairs includes oxygen concentrator Figure 30 Excerpt from Table of Number of Current Home Heath Care Patients with Aides and Devices in 2000 9 As such it is important to have reliable technology to support home care Home care can not only save patients and insurance companies money Fig 31 but living at home can provide patients a welcome and comfortable environment in which to recover and be monitored 29 Table 18 Cost of Inpatient Care Compared to Home Care Selected C
12. Alternative Design 2 Accessible Home Vital Signs Monitor Team 3 Robert Croce Jenna Sullivan Mike Kapinos Project For RERC National Design Competition Client Contact Dr John Enderle Director and Professor of Biomedical Engineering Program University of Connecticut Bronwell Building 260 Glenbrook Road Storrs CT 06269 2247 Phone 860 486 5521 FAX 860 486 2500 email jenderle bme uconn edu Table of Contents T Introdu cti n o LE v eR E dr E D OR ER CR En ct E Qe TI EE es 3 5 1 22 SUDUMIUS eck csc igen mcd o ee LEA UN D EI AU E 6 25 12 1 Thermometer el AE Lah aah dean Mes cone et dene ga 6 8 152 2 Pulse Oxiimeter 2 ier er Ie Ibi Ie lxv e PIeX ri trei 8 13 1 2 3 Non Invasive Blood Pressure ccessseeeeeee eee 13 16 Td Respiratory Rates uere eoa s o3 reon En d ERA PR ER M o EdaS AEE TEn 16 17 IESUS mE 17 18 1 2 6 MICFODFOCESSOE 5 set creed ERR REMEDIA RIS siemens EVE HEN DDIE i 18 20 1 2 dC DES Greens fide thee v cides ooo aede deren see De E chine 20 21 12 8 Speech OUIDUL i ducat d pee e verto dl e d e s 21 23 229 AL ArT ESTEE m E I 23 1 2 10 Secure Website cssseeeeeeeeeeeeee III III eere 24 132 TT Pow r SUPPLY totus is roc CORREO eta EO ON eb qd Ed a Ta ARCH EEEE 24 1 2 12 D SB POT ects Oy oes Od Cas ONS us LIC ur ENS rr 25 2 Realistic Constraints ccc ccc cece cece cece cece cece ese esses eese 26 28 d Safety ISSUES iioii arare ex Tn E EEE ute e
13. Jet will also serve as an alert The majority of the alarm design will be done by programming the microprocessor We will have a set of defined limits for each vital sign and if these signs fall out of range a signal from the microcontroller will be sent to the SpeakJet and alarm light v Y Y http img alibaba com photo 50538513 Alarm Lights Warning Lights jpg Figure 26 Alarm Light 23 1 2 10 Secure Website After the patients vital signs have been gathered and recorded they need to be sent to their primary healthcare provider To maximize patient privacy we have devised a way to securely transmit the patients health information minimizing the risk of interception We will create an encrypted password protected website to which the patient uploads the information from their USB stick To ensure that the website is secure HTML encryption software will be used to encrypt the contents of the website allowing only those with the correct username and password to access it We will use encryption software such as TagsLock Pro v 2 22 to hide the source code of our HTML documents To encrypt HTML using TagsLock PRO you need to create a new project once and re use it later when the site content gets modified and needs re uploading In order to use this encryption software a website using the UCONN Biomedical Engineering server will have to be created for the prototype accessible home vital signs monitoring system 1 2 11 Power Supply
14. LED driver Timing circuit Timing circuit circuit circuit Automatic gain Automatic gain control circuit control circuit Low pass filter Low pass filter Figure 6 Pulse Oximeter Circuit Block Diagram The pulse oximeter finger probe that we will use is the DRE Datascope compatible SpO2 finger probe with 8 pin connector for 165 00 price before shipping and tax from DREMed com Fig 7 http www dremed com catalog product info php cPath 205 210 products id 435 Figure 7 Datascope Compatible SpO2 Probe It contains two LEDs one that works at a red wavelength and the other at a near infrared NIR wavelength Also in the probe is a photodetector that will detect the light transmitted through the finger The red LED used in the probe has been manufactured to give high intensity output and the NIR LED is designed to be pulsed so that its peak power can be increased without increasing its average power By pulsing both light sources only one photodiode is needed to detect the light transmitted through the finger 15 To transmit light the LEDs need to be driven by a constant current source This can be done by a non inverting op amp combined with a FET Fig 8 In this circuit the current driving the LED is given by Ir gp Vi R 12V TU e Figure 8 Circuit for constant current LED driver To control the pulsing of the LEDs timing circuits need to be used For this we will use 555 timer circuits Fig 9 The 555 ti
15. al temperature probe and an automatic blood pressure cuff On the next page is an illustration of our design Fig 1 followed by a flowchart of our system operation Fig 2 Figure A 10cm Alarm Handle Crystalfontz LCD Screen 12cm Viewing Area 19cm 1 gt Blood Oxygen Level Heart rate ico sse 55 BPM sna Area 2 4cm Instruments 20cm Blood Pressure Body Temperature Respiratory Rate 1201180 98 6 F 798 6 F 15 2 BEI EX i c 41cm Speaker Figure B On Off Instrument Ports USB Port 20cm Figure C Power Cable 20cm E b 41cm Figure 1 Illustration of Design Power Button Pressed Device Powers On Are the transducers No connected to the patient Begin heart rate BP pulse oximetry and Button Begin blood temperature s Pressed d pressure readings Zz readings Record Stop button pressed Record readings to USB flashdrive Record Stop button pressed Readings stop recorded to USB flashdrive Figure 2 Flowchart of accessible vital signs monitor operation The following design differs from the first design in a few important ways First this new design is for a vital signs monitor that will measure 6 different vital signs Our last design only measured 4 vital signs heart rate blood oxygen saturation blood pressure and temperature but this de
16. ample and hold circuits 15 A simple sample and hold circuit can be created from a FET switch capacitor and op amp Fig 12 MIY M2N680 C3 in m 70 Figure 12 Sample and hold circuit Once the signal goes through the sample and hold circuit it is sent through a band pass filter with cutoff frequencies 5Hz and 5Hz to eliminate high frequency noise and the d c offset Then it is amplified and sent through an A D converter and the microprocessor to be analyzed A lookup table stored in the microprocessor will be used to calculate SpO values This signal is also sent through a low pass filter to extract the d c value of the transmitted signal which is then sent to an automatic gain control circuit The gain control circuit adjusts the light intensity from the LEDs so that the d c level always remains at the same value whatever the thickness of the patient s skin tissue etc This circuit is implemented by feeding the d c signal to one input of a differential amplifier The other input to the amplifier is a constant reference voltage The output of the differential amplifier the voltage difference between the two inputs is used to generate the voltage that sets the value of the LED currents 15 Calibration of the pulse oximeter will be done through the lookup table stored on the microprocessor Due to the scattering effects of blood Beer s Law does not apply for a pulse oximetry system 18 Therefore the blood oxygen s
17. anes 15 LT R spiratory Belt oce Iesu prev Io beer ere er Ra EE RRREUR o Qe SA AO RUNE EN A bed T I ad 17 T3 Distal Scales iu poda Deest oue o IR TO tiec rt co abro eat eo tered SN Odd as 18 LO BlackBn TIape o o eS bo d da EIE Rr e ap esas abdien kN bee a esas Rb cie iis 19 20 EZ Kit Lite Evaluation Board ss ie eee etes erae reo Ern PeeRPA TN EREEVRPRH E o IE 20 2I PLAG EIUIACOI S uote eratis ia i eem eI UNE e Time mU M Ve SIM 20 22 ECD Sereeti cie tires So ere ours cele hee eU eee tee ue efc 21 23 SPC SUC ios oro eer vtaxi SEE EC HIRR QURE CANTE cease Ges Ura PENNE MN A TS 22 24 Pim Diagram ot T L329364 5 boit Ves exa itta e exea dct eM ase the EN salas RO 22 25 Small Speaker for Audio OUtp t 2 uice ean reper eoru aporta mera E Yer ver ER d rey ae P ees 23 DO Alarm LEAS NG REN TT 23 241 Recharecable Battery caesa LoT GR RH ES E E a Ea 24 20 LI SBOSCeiatio oo eus ides nde ro Eden uM citer Cet MEL 25 29 Bruising caused by one use of an automatic blood pressure cuff cee 27 30 Table of Current Home Heath Care Patients with Aides and Devices in 2000 29 31 Table of Home Care Cost SaVIDBS o cedo si rece tao EXER oe Reo Se To Toa Perd Hs 30 Table 1 Respiratory Belt Specifications i rte ERROR ER REA EE Eds 17 Table 2 Blackfin Specifications io soscc ie aepo a e Sade EEA SEE ee Santee sce 19 1 Introduction Due to the increasing number of chronic illnesses along with the shortage of nurses hom
18. aturation equations explained previously are good for theory but not for practice As such pulse oximeters are usually calibrated by comparing the oximeter R value SpO ratio to the oxygen saturation ratio obtained from in vivo samples using human test subjects Manufacturers of pulse oximeters do this and determine calibration curves or lookup tables for their devices Because we are using a Datascope compatible probe we will obtain and load Datascope s lookup table onto our microprocessor The pulse oximeter will be tested through a pulse oximeter simulator a device designed to test the accuracy of pulse oximeters We plan to find a simulator to use at a local hospital or the UConn Health Center Heart Rate Pulse oximetry will also be used to determine heart rate There are pulsatile signals detected in the intensity of the detected light by the photodiode Fig 13 12 14 03 38 2 14 09 43 2 20 02 23 7 20 02 23 7 Figure 13 Pulsatile signals found in the intensity of detected light 15 One pulse is one cardiac cycle The microprocessor will count the pulses to determine heart rate beats per minute which will be displayed on an LCD screen 1 2 3 Non Invasive Blood Pressure Blood pressure will be automatically measured through the oscillometric method 14 This is done by wrapping a blood pressure cuff around the upper arm and inflating it until the pressure around the arm due to the cuff collapses or occludes the brac
19. device that we decided to use is the Philips PDIUSBD11 Fig 28 This device uses I2C technology to be able to connect to the microcontroller This allows for easy communication between the two By writing a computer program in the microcontroller we will be able to send the data received by the machine to the USB device and then to the computer The following image shows the schematic of a how the USB device will connect with the microcontroller EE qu PaA S81 Sy i i mim zB bab Conc hamba plab ap Faciplci adii i Figure 28 USB Schematic 25 2 Realistic Constraints The main source for medical instrumentation standards is the Association for the Advancement of Medical Instrumentation AAMI They provide for purchase the current standards of medical device design and use These standards must be followed in the design and production of our device to ensure that it is acceptable and safe for our clients and the health care community This device has been designed with the economic constraint of cost in mind We have a maximum budget of 2000 to build a working prototype of our device so parts were chosen carefully A balance had to be maintained between using parts that meet the needs of our design and not overspending our budget It may be especially important to have room left in our budget next semester when we begin the actual construction of our device We may need to order replacement parts or additional
20. e We learned about the optical properties of blood and the Beer Lambert law to design a pulse oximeter circuit Also from the pulse oximeter we saw the application of 31 transistors to switching and timing Research into an automated blood pressure measurement system highlighted the importance of control systems in medical devices Even for something as seemingly benign as an automatic blood pressure cuff system safety precautions have to be taken to ensure that a patient is not harmed through the use of the device This design also required us to learn about pressure sensors pressure release valves and air pumps Blood pressure waveforms were studied and the oscillometric method for blood pressure measurement was introduced to us We were also introduced to piezoelectric sensors used for converting changes in mechanical stress to voltage By incorporating a piezoelectric sensor into our respiratory belt we can obtain a voltage as the symmetry between the crystals change and pass this voltage through an analog to digital converter We learned that a respiratory belt responds linearly to changes in length and we can then use this to analyze a patient s breathing patterns 6 References 1 Basic Statistics About Home Health Care National Association for Home Care amp Hospice 2004 lt http www nahc org 04HC_Stats pdf gt 2 Blood Pressure Monitor lt http www circuitcellar com f12003 abstracts F190abstract pdf
21. e V 1 0 1 6 Core Voltage No Regulation 260 Figure 19 Blackfin Image ee PBGA 19 http www analog com images Product Descriptions 60475542243306341558700011339bf535 hardware jpg Figure 20 EZ Kit Lite Evaluation Board http www analog com images Product Descriptions 305 0239 903402849 11841 682443833402744562989 117500usb_emulator jpg Figure 21 JTAG Emulation 1 2 7 LCD Screens The digital information from the output of the microcontroller will be sent to six character LCD screens Fig 22 20 http www crystalfontz com products 16021 CFAH1602L Y YH JP front bl onjpg Figure 22 LCD Screen The CFAHI602L GGH JP LCD screens are ideal for our design due to its easy to read characters ideal size and wide viewing angles It measures 122mm x 44mm with a viewing area of 99mm x 24mm and a character height of 8 06mm These LCD screens were chosen due to the fact that many of the features meet the specific needs of our clients Since the majority of our clients will be viewing the monitor from their bed it is important that the screens should be viewable from a wide variety of angles Since these screens have a wide viewing angle patients will have no problem seeing their vital signs from their bed Also the yellow backlight makes this LCD screen easy to read especially in dark or dim lighted areas Also a viewing area of 99mm x 24mm makes the screens easy to read from a distance 1 2 8 Speech Output Our vita
22. e felt that LabVIEW would be a more suitable code to program the processor When designing a product with Blackfin many helpful tools are provided to the engineer to aide in the design which has already been purchased by the Biomedical Engineering department These include simulation software an evaluation board and an emulator Before the processor is even programmed VisualDSP software will be used to simulate the behavior of the DSP chip Using this software we will be able to build edit and debug our DSP program before we even have the actual processor which is done solely on the computer After the simulation is complete evaluation of the simulation is performed using the EZ KIT Lite evaluation system to determine the specific Blackfin processor that fits our needs This board Fig 20 connects up to the computer via a cable allowing us to run our simulation program After the evaluation process the JTAG emulation board Fig 21 will be used to serially scan the I O status of each pin on the device as well as control internal operations of the device This hardware connects our PC to the actual process target board via a USB cable Table 2 Blackfin Specifications Blackfin Specifications Clock Speed MHz 350MHz MMACS MAX 700 RAM Memory Kbytes 308 External Memory Bus 32bit Parallel Periph Interface No PCI Yes USB Device Yes UARTS Timers Yes Watchdog Timer RTC Yes Core Voltag
23. e monitoring is becoming more and more of a necessity Patients that require frequent healthcare monitoring can now have this done in the comfort of their own home An important tool for home health monitoring is the vital signs monitor Our accessible home vital signs monitoring system will have the capability to non invasively gather a patient s heart rate blood pressure blood oxygen level body temperature weight and respiratory rate and then send this data to their corresponding healthcare provider To send this data we will create a password protected encrypted website to which patients can upload their vital signs This accessible home vital signs monitoring system design is an accurate and consistent way to obtain a patient s vital signs regardless of the caregiver s skill level To accommodate all users including our clients the monitoring system was designed as simple and user friendly as possible Our three clients that are in need of an accessible home vital signs monitoring system are Mat Sani and Dolores Mat is a blind 52 year old male who just had a small stroke and lives with his vision impaired wife who loves the internet Sani is a 31 year old female who recently experienced a head injury from an automobile accident This accident left the right side of her body paralyzed her dominant side Her doctor monitors her vital signs by a computer system that is installed in her home but she does not want to appear sick to her famil
24. e will have to build handles onto the scale so people will be able to hold on and not fall The reason for this is that some of our clients are elderly and might not be able to stand steady on their own Also since this scale already has a main waist high base it should not be difficult to connect handles or rails The scale was also chosen because it is very inexpensive at 24 95 and it can be found at wholesalepoint com The scale has an on off switch and requires only one 9V batters for power As of now our main approach to connecting the scale to our device is a very simple and straight forward approach We plan on taking apart the scale and breaking the connection between the circuit and its digital display From here we just plan on simply connecting the scales circuit to one of our output displays instead The scale will already have been calibrated and tested by its manufacturer We will do additional testing by comparing known weight values dumbbells to the values displayed by the scale when we place the weights on it 1 2 6 Microprocessor The processor we are going to use for our design is the Blackfin ADSP BF535P Digital Signal Processor by Analog Devices Fig 19 This processor is extremely versatile due to the fact that it can function as both a microcontroller and a DSP Digital Signal Processor allowing for either 100 DSP 100 microcontroller or a combination of the two 5 This makes the Blackfin ideal for our design due to the
25. end up all over the World Wide Web By paying heed to these constraints and working with them not around them our accessible home vital signs monitoring system has been designed with the best interests of our clients and society at heart This ensures that we have designed an economically 27 feasible device affordable for our clients Our device is appropriately designed for the environment which it will be used in and with careful part selection it will sustain and continue to be appropriate for the home monitoring of vital signs 3 Safety Issues Safety plays a crucial role when designing a product especially one that contains electrical components Because our design will be comprised mainly of electrical components we strive to effectively enclose the inner circuit of our final design with a durable non conductive completely enclosed casing The casing of our final design will show no wires circuit boards or any part of the inner circuitry Loose wires will have the potential to not only cause the device to operate ineffectively but could also be hazardous to the patient Any moisture from the air or water accidentally spilled near the device could cause a spark and start a small fire It is for this reason that it will be recommended that all liquids be kept off of and way from the monitor regardless of how good the casing Also it is important for the casing to be made of a non conductive material such as plastic so that if
26. ent to a low pass filter to remove any noise The cutoff frequency for the filter should be less than 40Hz to remove any noise from room lights and other sources xz 6 Possible values for R2 and C are 2AR 1820Q and 2 2uF The signal will be sent to a non inverting amplifier to be amplified and then passed to the microprocessor where it will be analyzed and sent to an LCD screen to be displayed Fig 5 THERMISTOR RTI R2 c ue AW i 1 82k 2 Vo to microprocessor x Figure 5 Thermometer Circuit Values for R3 and R4 will be determined from gain equation for non inverting amplifiers The target gain for the amplifier will be based on the input current for the microprocessor The thermometer will be tested by placing the probe in a beaker of water heated to a certain temperature and comparing the resulting temperature given by the thermometer to the actual temperature of the water This will be done over a range of temperatures to determine the thermometer s actual operating range and to assure that is within the appropriate range to measure body temperature Final testing will be done by taking group members temperature with the thermometer and comparing the reading with that taken by a commercial digital thermometer 1 2 2 Pulse Oximeter To measure blood oxygen saturation a pulse oximeter will be used Pulse oximetry uses the optical properties of blood to determine oxygen saturation Blood oxygen satu
27. esign All About Electric Circuits 2003 lt http 72 14 209 104 search q cache HY M2hyPm4rcJ www allaboutcircuits com vol_1 chpt_3 8 html circuit designtsafety amp hl en amp gl us amp ct clnk amp cd 1 gt 14 Townsend Neil Non Invasive Blood Pressure Medical Electronics Michaelmas Term 2001 lt http www robots ox ac uk neil teaching lectures med_ elec notes7 pdf gt 15 Townsend Neil Pulse Oximetry Medical Electronics Michaelmas Term 2001 lt http www robots ox ac uk neil teaching lectures med_elec notes6 pdf gt 16 Volk Karl R Using thermistors in temperature tracking power supplies EDN August 2 2001 lt http www edn com article CA149117 html gt 17 Wattanapanitch Woradorn and Warut Suampun Portable Digital Blood Pressure Monitor Cornell University lt http www people cornell edu pages ws62 gt 18 Webster J G ed Design of Pulse Oximeters Philadelphia IOP Ltd Publishing 1997 33
28. gathering data relatively simple Even though the automatic blood pressure cuff is simple to use it is still not completely foolproof 4 Impact of Engineering Solutions Much of the technology used in our design for an accessible home vital signs monitoring system is not new but the manner in which it is being employed is valuable There are few if any accessible vital sign monitors currently available Patent and web searches have not devices on the market comparable in that regard to the device that we have designed The design of an accessible vital signs monitor will improve the quality of life for those individuals with hearing and vision impairment who need to have their vital signs monitored This device will allow those individuals the ability to go home to recuperate while still being effectively monitored by their health care provider This is especially important in cases where home health care would be a treatment option for someone without visual or hearing impairments but not for someone with them Home health care is a growing industry Approximately 7 6 million individuals receive home care in the United States The Center for Disease Control reported that in the United States in 2000 317 600 individuals in home care were using medical devices Fig 30 Medical Total with medical devices lll 317 600 15 900 31 700 58 300 74 300 84 800 52 600 Blood glucose monitor llle 132 500 11 800 19 200 38 600 37 300
29. hial artery The cuff is then slowly deflated As the cuff deflates blood starts pumping through the brachial artery causing minute vibrations of 5 to 1 mmHg in the cuff 2 The pressure at which these vibrations start is the systolic pressure and the pressure at which they stop is the diastolic pressure 3 The block diagram in Fig 16 illustrates how this method will be used to measure blood pressure in the accessible vital signs monitoring system Each system in the flow chart is described in more detail in the following paragraphs When the blood pressure Start button on the vital signs monitor is pressed the blood pressure cuff will be inflated to about 40mmHg above normal 160mmHg The blood pressure cuff used will be a DRE Adult single lumen cuff from DREMed com at a cost of 37 00 before shipping and tax Fig 14 http www dremed com catalog product info php cPath 56 121 241 242 products id 194 Figure 14 DRE Adult Single Lumen Blood Pressure Cuff 13 The cuff will be inflated by a Sensidyne AA Series Micro Air Pump A microprocessor second to the microprocessor controlling the rest of the device will control the inflation of the cuff The sensor used to sense cuff pressure will be the NPC 1210 low pressure sensor from GE Once the pressure sensor determines that the cuff has been inflated to 160mmHg the cuff will deflate slowly at a rate of 2 3mmHg sec Deflation will occur through a release valve brand to be determined
30. home use but in countries and areas with poor healthcare systems and little to no medical equipment it would be useful in a hospital or emergency room Because it is lightweight and has a rechargeable battery and because vital signs are saved onto a USB flashdrive our accessible vital signs monitoring system is an excellent option for remotely monitoring patients in areas where there are few trained medical personnel A layperson with no medical training could use our device to visit a patient who does not have access to a hospital or doctor and record their vitals signs on a USB flashdrive These measurements could then be uploaded to the secure website and accessed by doctors anywhere 5 Life Long Learning During the research of this design we were introduced to new and challenging engineering applications In updating our processing technique we learned about the Blackfin and digital signal processing Although we have already learned about FIR and IIR filters thus far in our engineering curriculum we were now able to apply these concepts to a real life situation Through researching digital signal processing we were able to compare it to traditional microcontroller design and see the differences Digital signal processing is not only substantially faster it also eliminates additional hardware associated with analog circuits Although analog circuits are cheap and easy to assemble software based DSPs provide flexibility in modification and
31. ies and physicians making it an ideal device for the home environment Since vitals signs are saved on a USB flashdrive to be uploaded to a secure website patients are not even stuck at home but can take their rechargeable battery powered vital signs monitor with them if they need to monitor their vital signs This offers flexibility and comfort to patients Economically the design for our device will reduce some of the costs of healthcare Vitals sign monitors and many of these are not accessible currently range in cost from 2500 up to 5000 Most of the monitors that measure the same four vitals signs as our device heart rate blood oxygen saturation blood pressure and temperature cost closer to 5000 If a patient s health insurance will not cover this cost than it becomes a large out of pocket expense for them or they may not be able to afford the device at all This is detrimental to their health and recovery By designing a monitor that s expected cost is 700 a third of the cost of the cheapest monitors currently 30 available we will be able to alleviate some of this financial stress and provide more comprehensive health care and monitoring to more people Globally this design may translate into an affordable piece of medical equipment for undeveloped countries With its two button user interface detachable transducers and simple design it may be useful in countries with a low level of technology Our device is designed for
32. iratory belt can be done by knowing the voltage of the piezoelectric sensors at rest Ideally there should zero voltage because there is no stress on the sensors If the sensors do exhibit some voltage the device will be zeroed at that corresponding voltage reading 16 http www adinstruments com products dataimages MLT1132Web jpg Figure 17 MLT1132 Piezo Respiratory Belt Table 1 Respiratory Belt Specifications 1 2 5 Weight Respiratory Belt Specifications Signal Source Piezo electric 20 mV to 400 Output Range mV 4 5 1 Sensitivity mV mm Device Capacitance 2 2 uF Device Resistance 10 Ohms Natural Frequency of Belt gt 35 Hz Connector BNC 300 mm Rest Length 11 8 Maximum Elongation 100 mm 3 9 Width 45 mm 1 8 Belt Length 1200 mm 3 9 Cable Length 2800 mm 9 2 Weight is an important vital sign to monitor In addition to ensuring proper eating habits weight is used to determine medication doses We will include weight monitoring into our vital signs monitor by buying a digital scale that exists on the market and connecting it to our device The scale that will be used is the Homedics SC 200 Digital Scale Fig 18 17 s p r CEPE ttt a mn vow Tw ar s were trat erens cete 2 I DIGITALSCALE c Figure 18 Homedics SC 200 Digital Scale This scale was chosen because it fits quite well with our project We figured with our clients w
33. l signs monitor will contain a text to speech function which will allow the monitor to say what the vital signs are once they have been recorded This function will be useful for our client Mat who is blind and cannot see the monitor Even though his wife is around to help him she is also vision impaired The output text from each pin on the microcontroller will need to be converted to sound To do this we will use the Magnevation SpeakJet IC Fig 23 It is an 18 pin IC which uses a mathematical sound algorithm to control an internal five channel sound synthesizer to produce sound The SpeakJet can be controlled by a single I O line from the Blackfin 12 Since this microchip requires phonetics and not text the TTS256 Text to Code IC will have to be used in conjunction with the SpeakJet The TTS256 is an 8 bit microprocessor programmed with letter to sound rules This built in algorithm allows for the automatic real time translation of English ASCII characters into allophone addresses compatible with the Magnevation SpeakJet Speech Synthesizer IC This IC is Compatible with Basic Stamp OOPic Pic and any processor with a serial port like our microchip 12 We will use pin 5 TX to output the phonetics from the SpeakJet and pin 18 RX to receive the data from the Blackfin Fig 24 The pin diagram of the TTS256 is shown below The final sound will be sent from the Voice Output pin 18 of the SpeakJet using 5V and a speaker Since the SpeakJe
34. le device and open the pressure release valve This method bypasses the microprocessor avoiding any software bugs that an emergency stop button might encounter As stated previously the automated blood pressure system will be calibrated experimentally This will be done through establishing a threshold voltage by which correct pressure measurements for systolic and diastolic pressures can be made Final 15 testing of the device will be done by comparing its blood pressure readings to those of a sphygmometer In the testing the sphygmometer will be operated by a nurse or other individual who is familiar with manually measuring blood pressures and does so often Nevertheless we expect to see some slight differences in the measurements from our device and the sphygmometer because of the inherent degree of imprecision in manual blood pressure measurement This is why it is important to have a professional operating the sphygmometer Their experience with the device and the art of blood pressure measurement should reduce the likelihood of human error Finally the rapid cuff deflation will be tested by experimentation turning the vital signs monitor off during use 1 2 4 Respiratory Rate To measure the respiratory rate of patients the MLT1132 Piezo Respiratory Belt Transducer from AD Instruments will be used Fig 17 Using a piezoelectric sensor placed between two strips this belt measures the changes in thoracic or abdominal circumference d
35. me These charges were multiplied by 30 days reflecting the above per patient per month costs Rich M W Beckham V Wittenberg C Leven C Freedland K and Carney R M A Multidisciplinary Intervention to Prevent the Readmission of Elderly Patients with Congestive Heart Failure The New England Journal of Medicine 333 no 18 1995 1190 1195 William D N et al Safety Efficacy and Cost Savings in an Outpatient Intravenous Antibiotic Program Clinical Therapy 15 1993 169 179 cited in Williams D Reducing Costs and Hospital Stay for Pneumonia with Home Intravenous Cefotaxime Treatment Results with a Computerized Ambulatory Drug Delivery System The American Journal of Medicine 97 no 2A 1994 50 55 Note The estimated hospital cost day patient is 417 and the estimated savings day patient is 262 These costs were multiplied by 30 days reflecting the above per patient per month costs Figure 31 Table of Home Care Cost Savings 1 When patients choose or have the option to enter home care they free up hospital beds for more acute cases give doctors more time to work with sicker people and many times patients they are happier at home than in the hospital But patients can not be cared for at home unless they have the proper technology to do so Our accessible vital signs monitoring device is a simple easy to use method to monitor patients health at home It can be operated by patients their famil
36. mers will supply 50ps pulses to the LEDs atarate of 1 kHz This is well above the maximum frequency in the arterial pulse which is never more than a few Hz Vcc P TRIGGER RESET OUTPUT 6 CONTROL THRESHOLD m Ez DISCHARGE Figure 9 Timing circuit 10 The values of the resistors can be determined from T 7 R R C and T 7R C where T is the pulse length 50us and T is the rate 1kHz or 1ms Thus values for R1 R2 and C2 are 56kQ 3 3kQ and 22nF respectively Finally an n channel enhancement mode MOSFET connected across the each LED is used to pulse the output from them Fig 10 R1 OPAMP zi DS135C Figure 10 Circuit to pulse the LEDs In the receiving end of the circuit is the photodetector The photodetector used in pulse oximetry probes is a photodiode The photodiode detects the light transmitted through the finger as current 15 To amplify the signal the photocurrent must be converted into a voltage with moderate output impedance This can be done by using an op amp configured for current to voltage conversion Fig 11 C Figure 11 Current to voltage photodiode conversion circuit 11 Because the LED light is pulsed sample and hold circuits are needed to reconstitute the waveforms at each of the two wavelengths The timing circuits that were used to control the red and NIR LED drivers also are used to provide the control pulses for their corresponding s
37. onditions Per patient Per month Per patient Per month Per patient Per month Conditions Hospital Costs Home Care Costs Dollar Savings Low birth weight 26 190 330 25 860 Ventilator dependent adults 21 570 7 050 14 520 Oxygen dependent children 12 090 5 250 6 840 Chemotherapy for children 68 870 55 950 13 920 with cancer Congestive heart failure 1 758 1 605 153 among the elderly Intravenous antibiotic therapy for cellulitis 12 510 4 650 7 860 Osteomyelitis others Sources Casiro O G McKenzie M E McFayden L Shapiro C Seshia M M K MacDonald N Moffat M and Cheang M S Earlier Discharge with Community based Intervention for Low Birth Weight Infants A Randomized Trial Pediatrics 92 no 1 1993 128 134 Bach J R Intinola P Alba A S and Holland LE The Ventilator assisted Individual Cost Analysis of Institutionalization vs Rehabilitation and In home Management Chest 101 no 1 1992 26 30 Field A I Rosenblatt A Pollack M M and Kaufman J Home Care Cost Effectiveness for Respiratory Technology dependent Children American Journal of Diseases of Children 145 1991 729 733 Close P Burkey E Kazak A Danz P and Lange B A Prospective Controlled Evaluation of Home Chemotherapy for Children with Cancer Pediatrics 95 no 6 1995 896 900 Note The study found that the daily charges for chemotherapy were 2 329 627 in the hospital and 1 865 833 at ho
38. parts as we go and we cannot do that if we have no money left within our budget Our accessible home vital signs monitor is meant for use in the home so varying environmental conditions are not a large concern of the device However being used in the home there were a few things we needed to keep in mind as we made our design Our device will be exposed to dust sunlight food and water Though it is not meant to withstand an onslaught of any of these things it was designed to be relatively robust in these conditions No parts were used that are very sensitive to movement or other household factors that could affect their use The device will have a durable plastic casing has been designed to withstand the typical rigors of home electronic life movement animals children cleaning spills etc That being said the device is not a toy nor was it designed to be one and the user should keep in mind the device s purpose when using it There are little to no concerns over our device s effect on the environment As it is a piece of home electronics it has very little effect on the environment as a whole Offshoots of the environmental constraints laid on our device are the accessibility constraints that it needs to meet Our device was designed to be properly accessible so that it will be of use to our clients and meet their needs Audio and visual output along with Braille and raised universal symbols were used to make the device user friendly to
39. ration SpOz is defined as the ratio of oxyhemoglobin HbO to the total concentration of hemoglobin in the blood Hb HbO HbO SpO aa P 2 THbo Hb6 This can be determined by measuring the difference in the light absorption spectra of oxyhemoglobin and deoxyhemoglobin 15 Assuming that the transmission of light through the arterial bed in the finger is only influenced by the concentrations of Hb and HbO and their absorption coefficients at two measurement wavelengths red and near infrared then the light intensity will follow the Beer Lambert Law Thus for an artery of length through which light of intensity In passes I 1 10 C769 at wavelength A1 and I 5 1 10 C67 9 at wavelength Az where Co is the concentration of HbO C is the concentration of Hb oon is the absorption coefficient of HbO2 at wavelength An and am is the absorption coefficient of Hb at Wav elength n Therefore if R um rU in2 then blood oxygen saturation can be calculated from C a R a S O o r2 rl m CG a TAn JR ay oO r Circuit Design The block diagram of the pulse oximeter below shows an overview of the circuits that are involved and will be included in the vital signs monitoring device Fig 6 Sample and Bandpass filter Amplifier hold circuit Current to Sample and hold circuit LCD Bandpass filter Amplifier Photodiode detector LO N MM NIR LED driver Red
40. sign adds the equipment to measure two more vital signs weight and respiratory rate The thermometer linearizing circuit has been changed from a resistor to a Wheatstone bridge which is more common in medical instrumentation and reduces heat created by the circuit itself Instead of purchasing an automated noninvasive blood pressure monitor and incorporating it into our device this report includes a design for an automated blood pressure system that will be part of the system itself Finally in this design we are using a Blackfin microprocessor instead of a PIC 16F877 The Blackfin was chosen for its superior processing capabilities and its ability to be programmed through LabVIEWTM 1 2 Subunits 1 2 1 Thermometer To measure body temperature a thermistor circuit will be used The thermistor will be in the form of a commercially purchased oral temperature probe The probe we have chosen for this is the Welch Allyn 02893 000 Sure Temp 690 Oral Probe from DREMed com for a cost of 74 00 before shipping and tax Fig 3 http www dremed com catalog product info php products 1d 1214 Figure 3 Welch Allyn Sure Temp 690 Oral Temperature Probe The thermistor within the probe will convert changes in temperature to changes in voltage Unfortunately thermistors are inherently non linear The Steinhart Hart equation describes the resistance temperature curve of a thermistor 16 7 a bin R cln R where T is the temperature in kelvins
41. t is preconfigured with 72 speech elements 43 sound effects and 12 DTMF touch tones we will also use the SpeakJet to produce an alarm when the vital signs are out of range range to be determined This chip will be tested 21 experimentally by providing to it a series of inputs to confirm that it is giving the correct outputs http www speechchips com images SpeakJetIC jpg Figure 23 SpeakJet IC 4 TX TTS256 on oO Pp OH J_BUF_FULL RX http www speechchips com images tts256 gif Figure 24 Pin Diagram of TTS256 To play these computer generated sounds a speaker from Futurelec Fig 25 will be purchased and attached to the microcontroller This speaker was chosen due to its small size and affordable price This speaker will be used to play the data output from the 22 microprocessor as well as sound an alarm when the patients vital signs become irregular http www futurlec com Pictures Sm Speaker jpg Figure 25 Small Speaker for Audio Output Features Small Size Power rating 0 5W Impedance 8 ohm Dimensions 50mm Diameter 16mm High 28mm base diameter 1 2 9 Alarm To assist our clients we will install an alarm system to alert them when their vital signs have become irregular or dangerous On top of the monitor will sit a light that will flash when these signs become abnormal A light we have chosen is shown below Fig 26 In addition an alarm sound generated by the Speak
42. ue to respiration inhalation and exhalation By stretching the elastic due to respiration strain is placed on the sensor which generates a voltage Piezoelectricity is the ability of crystals to generate voltage in response to applied mechanical stress Ina piezoelectric crystal the positive and negative electrical charges are separated but symmetrically distributed so that the crystal overall is electrically neutral When a mechanical stress is applied such as the stress applied to the straps as respiration occurs this symmetry is disturbed and the charge asymmetry generates a voltage across the material The voltage produced responds linearly to the mechanical stress applied to it This voltage is then sent through the transducer and converted into digital signals to be processed by the Blackfin In plotting the voltage sent from the transducer we can count each breath as a peak on the graph which corresponds to the maximum distance the belt traveled for that breath In monitoring a patient s respiratory rate the adult patient should have an average of 12 20 breaths per minute Below is a picture of the respiratory belt With an adjustable belt length of 3 9 feet Table 1 it can accommodate all sizes of patients To test the accuracy of this transducer we will compare our results obtained from using this respiratory belt to the results obtained the BioPac software Any modifications can be made using the software internally Calibrating the resp
43. y and friends She would like a vital signs monitoring device that blends in with the other furniture in her home Our last client is Dolores She is an 86 year old female who lives with her son his wife and their son Dolores is deaf and has severe arthritis She also has heart problems that cause her to receive infusions at home These infusions are normally administered by one of her family members Dolores grandson Tyler is 11 years old and he likes all kinds of electrical gadgets He loves to help his grandmother collect her vital signs and send them to her doctors on the computer To maximize the simplicity of our design and make it accessible to our clients the buttons on the front panel of the monitor will be large and printed with either Braille or a universal symbol allowing patients who are vision impaired or have arthritis to successfully operate the monitor Also to accommodate vision impaired clients a text to speech function will be implemented to allow the monitor to audibly tell the patients what their current vital signs are In addition four bright LCD screens with wide viewing angles will be used to display the patients vital signs A visual and audio alarm will be installed to alert clients if their vital signs are abnormal To collect the data medical transducers will be commercially purchased and integrated into the accessible vital signs monitoring system The items to be purchased are a finger pulse oximeter probe an or
44. yt aida atate EERE tes 28 29 4 Impact of Engineering Solutions esee 29 31 Di Life Long Leathint RC I ULT LS 31 32 6 XReICrelCcesoo mone one hi od Ea AES eie pnr ne Alas hae ng ncaa te 32 33 Figures and Tables 1 Illustration of Vital Signs Monitor cesses m mem nene 4 2 Flowchart of Vital Signs Monitor Operation sess 5 30r Temperature Probe siia e Too TOS DOG tid dius 6 4 Thermometer Linearizing CAECUM cud rods rt VE anid ah DOR EX X VEEORR UR a SUCH makes 6 3 Tiermorieter C ITO o1 eoa exco A Erba o e SE E t seul ana EEUU MA san 7 6 Pulse Oximeter Circuit Block Diagram 1 eese eerta reete ta enr rre t nennen 9 Ta Pulse Oximeter Finger Probe 25e sche tee aueon e eee takes an ed aoo beta em rd ed 9 8 Circuit for constant current LED fiver sacer ver th ern rh emt en pA Rt ta de 10 OF Tipo IECUIL S a ted eere Qi do eure rdi tdeo tut uate ode coe cene LE 10 10 Circuit to pulse the EBD ooo ee eer e eve estt 11 11 Current to voltage photodiode conversion Circuit 6 cece eee e eee neee eee eneeaeaee 11 12 Samplesand hold cirit esseere uane ohe bees EEE T Enns 12 13 Pulsatile signals found in the intensity of detected light c ce ceeee eee eee es 13 I4 Blood Pressure CUE is see EOD o exibito etcetera races Ea AE 13 15 Blood Pressure Waveform coo y Ext TR NEHME CD txt a neta 14 16 Block Diagram of Blood Pressure System 0 cece eee ee cece eee eee tease een
Download Pdf Manuals
Related Search