RERC Report
Contents
1. http www crystalfontz com products 16021 CFAH1602L Y YH JP_front_ bl on jpg Figure 18 LCD Screen The CFAH1602L GGH JP LCD screen is 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 Since this screen has a wide viewing angle clients 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 The 99mm x 24mm viewing area makes the screens easy to read from a distance as well 2 2 8 Speech Output 12 As well as being displayed onto the LCD screen the vital signs are also spoken This was made possible by utilizing the SP03 text to speech module which takes strings of ASCII text and produces the resulting speech ie 4 E bond Waray ey OURPSRT ALLOA E fot slis er a to a h z fae i k HE fa cio a Gi z R3232 Ra R5232 Tx This was made possible by the use of RS232 serial communication The only pins that needed to be used on the SP03 were the Rx Tx ground and 5V pins A SP232ACP 16 pin chip was used to convert the TTL to serial The Rx and Tx pins from the SP03 were connected to the corresponding pins 13 and 14 on the SP232ACP then sent to pins 25 and 26 on the PICI16F877 To communicate between the SP03 and microchip USART was used This communication allows2. A remote healthcare provider can use the same path to download vital signs files simply by not entering a file name in the upload field on the Upload Site 2 3 4 Client Testing Because our clients our hypothetical we tested our device with our clients by simulating their disabilities The Accessible Home Vital Signs Monitoring System was tested by simulating blindness and dominant side paralysis Only the use of the monitor was tested as from the RERC project brief it is assumed that the clients can already use a computer or have family or assistants that can use a computer Multiple subjects were tested plugging in and using the probes and the monitor 2 3 4 1 Partial Paralysis 20 Simulating partial paralysis on the dominant side subjects were able to plug all of the probes into the side of the device one handed Figure 40 Subject Inserting the Figure 41 Subject Plugging Scale Plug into the Jack Probes in with One Hand Though it was difficult the subject was also able to attach the blood pressure cuff using only one hand This should not pose a problem to our clients because they all have assistance available at home Figure 42 Subject Simulating Partial Paralysis Wrapping the Blood Pressure Cuff Around His Arm 2 3 4 2 Blindness To simulate blindness subjects were blindfolded and asked to operate the device With no description of the device subjects were able to plug all of the plugs into the proper jacks locate butt
3. 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 testing of the device will be done by comparing its blood pressure readings to those of a sphygmometer 2 1 4 Respiratory Rate Respiratory rate in this design will be measured using a thermocouple The thermocouple will be clipped to the client s nose and will measure the change in temperature caused by inspiration and expiration Fig 2 The thermocouple will convert the changes in temperature it detects to changes in voltage Through experimentation voltages thresholds will be set to define the changes in temperature that correspond to inspiration and expiration By counting the number of inspiration and expiration pairs that occur in a given period of time we can determine respiratory rate Figure 2 Image of Thermocouple Nose Clip The voltage from the thermocouple will be linear over our range approx 65 F to 98 F so the signal from the thermocouple only needs to be filtered and amplified before being A D converted and processed by the microprocessor As mentioned previously this circuit will be calibrated experimentally Voltage output from the thermocouple will be measured for inspiration and expiration From these measurements voltage thresholds will be set for inspiration and expiration Testing will be done by
4. clients computers are not Bluetooth ready a USB Bluetooth dongle provides connectivity on the PC end Our Bluetooth communications system was calibrated through UART communication It was programmed to set up a network with the Bluetooth USB dongle when it detects it The Bluetooth system was tested by acquiring vitals signs from the monitor and sending them to a computer in the design lab to which the USB dongle is installed 2 2 12 Pushbuttons and Casing Three buttons were used in our design This was intentionally done to create an easy and non threatening user interface Two square buttons one to transmit data the other to inflate the blood pressure cuff with wings allowing the button to be snapped in are on the front on the monitor A rocker switch on the left side of the monitor turns the device on and off This differentiation between the function buttons and the on off switch was also done to increase accessibility and ease of use In order to safely enclose the internal circuitry of our design a plastic enclosure needs to be manufactured A casing from BoxEnclosures was ordered and holes for the buttons LCD screen and probes machined in the machine shop and design lab 2 2 13 Accessible Vital Signs Monitor Circuit Diagram 14 wey oa a Yo B ap a cmp Ue y LCD Screen i _ A pw hy D i 7m iii A UCONN BME er g j5 w F D Home Vital Signs Monitor e Guo ty apria iaga PICIGF
5. comparing the readings from our respiratory rate monitor to those taken by the Biopac respiratory belt from the Biopac software used in the ENGR 166 lab 2 1 5 Weight Weight will be monitored by digital bathroom scale The scale that will be used is the Homedics SC 200 Digital Scale We plan on taking apart the scale and breaking the connection between the circuit and its digital display From here we will connect the scale s circuit to our output display 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 2 1 6 USB Device Vital signs readings will be stored via a USB flashdrive This device will then be connected to a computer to download vital signs The USB device that we decided to use is the Philips PDIUSBD11 This device uses I2C technology to connect to the microprocessor This allows for easy communication between the two By writing a computer program in the microprocessor we will be able to send the data received by the machine to the USB device and then to the computer we Coogee oe m 1 4 GM 2 Dr i Ge cs ca ci ELL Zari iE mi Figure 3 Sample USB Schematic 2 1 7 Power Supply The device will mainly be run from an external power source by using a power cord It will also be equipped with backup batteries in case of a power failure For
6. of this need for in vivo testing for calibration even if we constructed a pulse oximeter from scratch we would not be able to test it or calibrate it Therefore to save time in construction we purchased a commercial fingertip pulse oximeter to incorporate into our monitor The pulse oximeter chosen is the Drive Reflectance Fingertip Pulse Oximeter Fig 8 Figure 8 Drive Fingertip Pulse Oximeter For simplicity the signal from the pulse oximeter is taken across the photodiode It was found by mapping the pins that connect to the ribbon string that connect to the photodiode and power source Fig 9 Figure 9 Mapped Pulse Oximeter Pins 1 and 5 were found to connect across the battery and pins 2 and 3 connect across the photodiode itself Since the voltage blood oxygen saturation curves for this pulse oximeter belong to Drive and we did not have access to them we calibrated the pulse oximeter by setting a voltage threshold above which the LCD screen on the monitor outputs 98 Blood Oxygen Saturation This voltage threshold was set by scoping the outputs of pins 2 and 3 while the pulse oximeter was operating on the finger of a healthy individual Fig 10 Figure 10 Pulse Oximeter Signal Across the Photodiode The voltage threshold for when the photodiode 1s detecting the light transmitted through the finger of a healthy adult was found to be approximately 250mV Though the pulse oximeter in our monitor will not actual
7. other sources f 9 The final circuit for the thermometer is seen below Fig 7 2AR C E ad eer ae e Figure 7 Completed Thermometer cin Including Amplifiers and Filter Because we did not have the manufacturer s thermistor coefficient data we had to determine our temperature versus resistance curve experimentally to calibrate the thermometer The thermometer was calibrated by calculating a curve that relates thermistor resistance to temperature in degrees Fahrenheit Calculations yielded the following equation l T T 2 82857 Vo 1 65 133 199 857143 Final testing done by taking group members temperature with the thermometer and comparing the reading with that taken by a commercial digital thermometer showed that the thermometer was accurate to within S F 2 2 2 Pulse Oximeter To measure blood oxygen saturation a pulse oximeter is used Pulse oximetry uses the optical properties of blood to determine oxygen saturation Due to the scattering effects of blood Beer s Law does not apply for a pulse oximetry system 19 Therefore blood oxygen saturation equations are good for theory but not for practice 19 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
8. 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 For the backup power supply we determined the best way would be to use nickel cadmium rechargeable batteries 2 1 8 Secure E mail System In other designs we sent the vital signs data through a secure website Another viable option that we explore in this design is a secure e mail system This can be accomplished through certifiedmail com This website provides the software necessary to protect e mail using transparent encryption It provides easy to use software that the recipient of the e mail does not need to download in order for complete security to occur There is no password required and information is automatically secured every time with the Certified Mail software It is also possible to track the e mail to determine that the e mail was received and who opened it A one time download and 10 per month provides these features 2 1 9 Processing Display and Alarm The processor we are going to use for this design is the Blackfin ADSP BF535P Digital Signal Processor by Analog Devices Like the PIC microcontrollers the Blackfin contains an internal analog to digital converter 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 micropr
9. Accessible Figure 26 Open View of Top of Accessible Home Vital Signs Monitoring System Monitor Vital Signs Monitoring System Monitor iR mOi a Pockets for Probe Storage Figure 27 Read View of the Accessible Home Vital Signs Monitoring System Monitor 2 3 2 Probes for Vital Sign Acquisition Four detachable probes are included with the Accessible Home Vital Signs Monitoring System Each of the four probes plugs into a jack on the right side of the monitor All four probe plugs are different sizes and only fit into one jack on the right side of the monitor 16 The thermometer probe is attached to a 6 ft cable that ends in a 1 8 phone plug To use the probe plug must be inserted into the corresponding 1 8 phone jack and the thermometer placed under the tongue Fig 28 Figure 28 Thermometer Probe The respiratory rate probe included is on a retractable cable This probe terminates in a 3 32 plug On the other end of the probe is a thermocouple which measures changes in temperature Fig 29 To measure respiratory rate the plug must be inserted into the corresponding 2 32 plug on the right side of the monitor Breathing regularly with the mouth closed through the nose only the thermocouple end of the probe must be clipped or held up to the nose so that the thermocouple hangs under one of the nostrils Figure 29 Thermocouple Probe on Retractable Cable To measure weight a digital bathroom scale is i
10. ET Figure 23 PCB Diagram of the Board The previous figure combines all of the above subunits into a circuit diagram This is a basic diagram of our complete vital signs monitor Figs 22 23 2 3 Prototype 2 3 1 Overview The Accessible Home Vital Signs Monitoring System uses noninvasive existing medical technologies to monitor a client s vitals signs from home It includes probes to monitor six 6 different vital signs heart rate blood pressure temperature weight blood oxygen saturation and respiratory rate A 16x2 character LCD screen displays a client s vital signs as they are acquired and a speaker outputs the spoken vitals signs from a text to speech module A rocker switch on the left side of the monitor turns 15 the device on and off and four jacks on the right side of the monitor accept probes that acquire 4 of the 6 vital signs When depressed a square red button on the bottom left corner of the monitor sends the acquired vital signs to a computer via a Bluetooth module within the device The square green button on the bottom right corner of the monitor starts the inflation of the blood pressure cuff A cloth casing and cover provides style and pouches on the back of the monitor to hold probes and accessories Figs 24 25 26 27 Figure 24 Front View of the Accessible Home Vital Signs Monitoring System Monitor k f Pulse Oximeter Finger Port gt Figure 25 Side View of the
11. RERC Report Accessible Home Vital Signs Monitoring System by Robert Croce and Jenna M Sullivan Team 3 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 1 Introduction 1 1 Background With the aging baby boomer population home health care is a growing and changing industry The advent of telemedicine and advanced communications technology has allowed medical patient monitoring to move from the hospital to the home By monitoring patients statuses remotely health care facilities can free up hospital beds and doctors time for more critical patients An integral part of remotely monitoring a patient s condition is the vital signs monitor There are many clients who are in need of an accessible home vital signs monitoring system To make this device as accessible as possible we have to address the many needs of all of our clients An overview of these needs can be seen in three of our clients Mat Sani and Dolores Mat is a 52 year old male in good physical condition He is blind and works as a radio commentator Mat just had a small stroke and his doctor wants to monitor his vital signs from home for the next 90 days Mat does not like devices that are very technologically advanced but lives with his vision impaired wife who loves the internet Sani is a 31 year old female who recentl
12. ckt1 therm_cktl htm gt 10 Northrop Robert B Noninvasive Instrumentation and Measurements in Medical Diagnosis New York CRC Press 2002 11 Northrop Robert B Class notes BME 255 University of Connecticut Oct 17 2006 12 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 gt 13 SpeakJet User s Manual Magnivation 2004 lt http www speechchips com downloads speakjetusermanual pdf gt 14 Safe Circuit Design All About Electric Circuits 2003 lt http 72 14 209 104 search q cache HYM2hyPm4rcJ www allaboutcircuits com vol_1 chpt_3 8 html circuitt designtsafety amp hl en amp gl us amp ct clnk amp cd 1 gt 15 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 16 Townsend Neil Pulse Oximetry Medical Electronics Michaelmas Term 2001 lt http www robots ox ac uk neil teaching lectures med_elec notes6 pdf gt 17 Volk Karl R Using thermistors in temperature tracking power supplies EDN August 2 2001 lt http www edn com article CA 149117 html gt 18 Wattanapanitch Woradorn and Warut Suampun Portable Digital Blood Pressure Monitor Cornell University lt http www people cornell
13. edu pages ws62 gt 19 Webster J G ed Design of Pulse Oximeters Philadelphia IOP Ltd Publishing 1997 6 Acknowledgements We would like to acknowledge the following people to thank them for their support and assistance with our project Rehabilitation Engineering Research Center on Accessible Medical Instrumentation RERC AMI National Student Design Competition funding Dr John Enderle Client Contact and Advisor Mr Willian Pruehsner Advisor John Chandy David Price David Kaputa Lisa Ephraim Jennifer Godino 24 Rich and Serge Machine Shop A7 Engineering partial sponsorship of Bluetooth development kit Emily Dufresne EmComm 25
14. en saturation a pulse oximeter will be used 16 The circuit design can be seen in Fig 1 A finger probe will be constructed rather than bought to reduce cost The finger probe that we will use with our device will need a red LED a NIR LED and a photodiode The LEDs will be placed opposite the photodiode within a casing that can be clipped to a finger One LED will work at a red wavelength 660nm and the other at a near infrared NIR wavelength 910nm Also in the probe will be a photodetector that will detect the light transmitted through the finger Figure 1 Pulse Oximeter Circuit Diagram Calibration of the pulse oximeter will be done through the lookup table stored on the microprocessor Manufacturers of pulse oximeters determine calibration curves or lookup tables for their devices The pulse oximeter will be calibrated 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 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 This function will be tested by comparing the heart rate given by the pulse oximeter to that of a group member taken ma
15. hat arise with automatic blood pressure systems we have incorporated a kill switch into our design 18 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 whole 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 was calibrated experimentally while relying on the work done by Wattanapanitch et al 18 This was done through establishing a threshold voltage by which correct pressure measurements for systolic and diastolic pressures could be made Final testing of the device was done by comparing its blood pressure readings to those of a sphygmometer Nevertheless we expected and encountered slight differences in the measurements from our device and the sphygmometer because of the inherent degree of imprecision in manual blood pressure measurement 2 2 4 Respiratory Rate Respiratory rate is measured using a thermocouple The thermocouple is clipped to the client s nose and measures the change in temperature caused by inspiration and expiration Fig 14 The thermocouple converts the changes in temperature it detects to changes in voltage Through experimentation voltages threshold were set to define the changes in
16. hipwe daystioping Banery space sess sawer Lion 10680 11 10 Banery amp Smart Charger Dake s maw or ooo Expresses se swor posea paky so mow poirem moroi o o Newbury Comes sear awor esmmreracanecae e s sewonsnapsaravero sw sso Pocket tobo shouerbag evs sa so hosa Raiosra snos wemeooz assorted jaoks plugs IC sockets pert Boara radoshack sse soseor pc voas resies o o s s s no s LS 1 3 2007 2 20 2007 3 28 2007 3 28 2007 4 6 2007 4 17 2007 4 17 2007 4 18 2007 4 23 2007 4 25 2007 s1380 E Jo Ann Fabrics 10 62 Table 3 Estimated cost to manufacture ZZ cence Me ECA Feral cer CT Fluid Power without shipping 37 60 Parker Pneumatic Valve We d like to note that this manufacturing cost could be brought down under 1000 by using a 2 layer PCB instead of 4 layers we did this due to time constraints and by constructing a pulse oximeter from scratch Taking this things into account would put the manufacturing costs for one unit around 800 900 Either total 1000 or 800 is far below current vital signs product prices 4 Conclusion Though in the end our prototype was never fully functional it was designed and built with the principles and performance measures of universal design in mind as listed by the RERC AMI website http www rerc ami org ami projects d 2 udg An obvio
17. illed in the cap of the thermometer with a drill press so that a cable purchased from RadioShack 6 ft shielded cable 1 8 plug to stripped wires could fit into the thermometer The thermistor leads and these cable leads were soldered to a small piece of PCB inside the thermometer casing This completes the thermometer probe Fig 5 Figure 5 Thermometer Probe with Attached Cable The thermistor within the probe converts changes in temperature to changes in voltage Unfortunately thermistors are inherently non linear This output can be linearized over a small range of temperatures through the use of a Wheatstone bridge Fig 6 THERMISTOR RTI v1 Yvo Y1 Y2 Differential Amp Figure 6 Thermistor Linearizing Circuit 11 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 B 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 is sent to a3rd order Butterworth low pass filter to remove any noise The cutoff frequency for the filter is about 60Hz to remove any noise from room lights and
18. is rate through the tubing with the help of two pin holes A basic circuit for the automated blood pressure system is seen in Figure 12 The pump and valve are powered by the battery and controlled by the microprocessor The pressure sensor also receives power from the battery and it sends signals to the microprocessor Pump alve Assembly Cuff VY from microprocessor LPF vb to microprocessor OP AMA R1 Figure 12 Automated Blood Pressure System Circuit As blood begins flowing through the brachial artery again it causes small pulsations that are picked up by the pressure sensor in the cuff Fig 13 This waveform is analyzed by the microprocessor to determine the systolic and diastolic pressures p8p Coo A ee eT ET LT CTT eee il ie A ee ee 10 15 20 25 30 35 Time seconds Figure 13 Blood Pressure Waveform Picked Up by Pressure Sensor 17 Where MAP Maximum Arterial Pressure SBP Systolic Blood Pressure DBP Diastolic Blood Pressure Vo Volts A threshold voltage level has been set by experimentally comparing blood pressure readings from a sphygmometer to those detected by our pressure sensor Once pulsations peak above the threshold level the voltage is recorded and from that value the systolic pressure determined The microprocessor continues to monitor the blood pressure readings and the diastolic pressure is taken when the voltage drops below the threshold voltage 18 Due to the safety issues t
19. lients want to maintain their health not appear sick to their friends and continue to live with their families The device we design will allow them to do these things It will be accessible to the vision and hearing impaired and it will be cost effective Most systems available today are very expensive and our purpose is to make an affordable device that is also accessible and easy to use 2 Project Design 2 1 Alternative Design 2 1 1 Thermometer To measure body temperature a thermistor circuit will be used The probe chosen for this is the Welch Allyn 02893 000 Sure Temp 690 Oral Probe from DREMed com 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 After being linearized the signal will be filtered amplified and then passed to the microprocessor where it will be analyzed and sent to an LCD screen to be displayed 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 We feel an appropriate temperature range to test this would be from 32 C to 40 C 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 2 1 2 Pulse Oximeter To measure blood oxyg
20. ly measure blood oxygen saturation it is included because it is an important vital sign to monitor Should we have been able to calibrate a pulse oximeter we could have constructed one from the pulse oximeter design in the alternative design 2 2 3 Non Invasive Blood Pressure Blood pressure is automatically measured through the oscillometric method 15 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 brachial 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 4 The pressure at which these vibrations start is the systolic pressure and the pressure at which they stop is the diastolic pressure 5 When the blood pressure Start button on the vital signs monitor is pressed the blood pressure cuff is inflated to about 40mmHg above normal 160mmHg The blood pressure cuff used is a Large Adult Cuff from CVS Fig 11 Figure 11 Adult Large CVS Blood Pressure Cuff The cuff is inflated by a Hargraves Fluidics CTS Series Micro Air Pump The microprocessor controls the inflation of the cuff The sensor used to sense cuff pressure is the MPX2050 Once the pressure sensor determines that the cuff has been inflated to 160mmHg the cuff will deflate slowly at a rate of 2 3mmH g sec Deflation occurs automatically at th
21. ncluded with a 1 4 phone plug that connects to the corresponding jack on the monitor To use only as a bathroom scale do not plug the scale into the monitor When the scale is plugged into the monitor the weight measured is saved by the microprocessor and sent with the other vital signs to the computer via Bluetooth The scale is activated by stepping on it Fig 30 e Figure 30 Digital Bathroom Scale that Can Be Used as a Stand Alone or as Part of the Monitoring System The last part to be plugged into the right side of the monitor is the blood pressure cuff Fig 31 17 Figure 31 Blood Pressure Cuff The cuff plugs into the connector at the top of the right side of the monitor which leads to the air pump For safety the cuff does not inflate immediately upon power up of the system To operate wrap the cuff around the upper arm aligning the artery mark on the cuff correctly When ready press the blood pressure button and the cuff will begin to inflate The cuff will automatically deflate upon reaching 160mmHg Should any discomfort occur during blood pressure measurement the cuff can be immediately deflated by turning off the monitor toggle the on off button on the left side of the monitor to the off position The blood pressure system measures not only but pressure but also heart rate Blood oxygen saturation is measured through a pulse oximeter that is installed inside the monitor The pulse oximeter is mounted
22. nitor we are using an 11 4V lithium ion rechargeable battery pack Although lead acid batteries can sometimes produce more voltage lithium ion batteries are safer and will recharge quicker These batteries are internal to the device and can be recharged with the included wall charger The need for a rechargeable battery is so the client can take their vital signs even if the power is gone and so that the system can be portable Regarding the power source it will be in charge of taking power from a battery and transferring that power into our system To bring down the voltage levels linear voltage regulators are used 2 2 11 Bluetooth To increase accessibility we added a Bluetooth option to transmit the data collected by the vital signs monitor to the client s computer wirelessly The weak signals that Bluetooth uses combined with frequency hopping makes it a secure way to transmit data The EmbeddedBlue eb505 SER OEM Bluetooth Serial Module from A7 Engineering provides Bluetooth connectivity for our monitor Fig 21 h See rerrre TES E 7 Figure 21 EmbeddedBlue eb505 SER OEM Bluetooth Serial Module E e oe s sal s a F Mal Toe eeeeeeeie The interface between our processor and the eb505 SER radio is done through UART communication When a connection is made to another Bluetooth device the link will appear as a cabled serial connection which eliminates the need for any special wireless protocol knowledge Assuming that our
23. nually 2 1 3 Non Invasive Blood Pressure Blood pressure will be automatically measured through the oscillometric method 15 The blood pressure cuff used will be a DRE Adult single lumen cuff from DREMed com 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 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 This waveform will be analyzed by the microprocessor to determine the systolic and diastolic pressures Due to the safety issues that arise with automatic blood pressure systems we have incorporated a kill switch into our design 18 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 whole device and open the pressure release valve This method bypasses the microprocessor avoiding any software bugs that an emergency stop button might encounter The
24. ocessor we need for our device The Blackfin can take C C code as well as LabVIEW Vi s After the data has been processed the information will be sent to 4 different areas the LCD display the speech module the speaker and alarm The process and parts to produce audio include the Magnevation SpeakJet IC in conjunction with the TTS256 Text to Code IC to produce speech To play these sounds and the alarm a commercial SW 8 Ohm speaker will be purchased The alarm will include audio and visual features that will turn on when the client s vital signs become abnormal 2 2 Final Design Power Button Pressed Device Powers On Are the transducers connected to the patient Begin heart rate pulse oximetry and temperature readings BP Button Pressed Begin blood pressure readings Send button pushed Readings sent via Bluetooth to the computer Readings saved Readings uploaded to secure website Figure 4 Flowchart of Accessible Vital Signs Monitor Operation 2 2 1 Thermometer To measure body temperature a thermistor circuit is used The thermistor is in the form of a commercially purchased oral temperature thermometer that was converted into a temperature probe In order to reduce costs and make a recognizable probe a digital thermometer was purchased from CVS and all of the circuitry pulled out of it leaving just the casing and the thermistor in the tip A hole was dr
25. omatically made between the Bluetooth module and the Bluetooth dongle also included If the Bluetooth dongle is not plugged into one of the computer s USB ports the Send button will have no effect Fig 37 A a 2 perm te k Figure 37 Bluetooth Dongle Plugged into One of the Computer s USB Ports Once the Bluetooth dongle has been plugged into the computer the Bluetooth module may have to be installed To check to see if the Bluetooth module needs to be installed press the Send button and see 19 if the data sends If the module needs to be installed the following steps can be followed to do so once the monitor and computer have been turned on Once the vital signs have been sent to the computer they can be save as a text file and then uploaded to the secure website A mock up of the website is currently held on the Team 3 website on the BME server Fig 38 jE Uneiied Document lt tapika Firea 166 A ar jen Secure Upload Site Login Page Uwe Figure 38 Secure Login Site Once the client logs in they are taken to a site where they can upload their files Fig 39 OB eiid Dorise ardia firea r i Te baa Tai panmi gt miui D u G eet a Figure 39 Upload Site When the User Can Upload up to Three Files at a Time Once upload the client is taken to a site containing the files that they have just uploaded This site also allows the vital signs files to be downloaded
26. ons and use the pulse oximeter Figure 43 Subject Using Touch to Figure 44 Blindfolded Subject Find the Thermometer Probe Plugging in the Probes 21 Figure 45 Subject Finding and Operating Figure 46 Blindfolded Subject the Blood Pressure Button Using the Pulse Oximeter 3 Budget Table 2 Design Budget moz s200000 S 1 3 2007 4862 1 3 2007 176 97 Loe 1 9 2007 122mm x 44 mm PCB Size Green LED Backlight Credit for returning 5 crystal Fontz LCD Screens Crystal Fontz 95 79 2 22 2007 RMA DP7245 1 15 2007 Blackfin BF535 Processor Whole Sale Point 26 95 1 9 2007 Homedics Digital Bathroom Scale USB Chip and 1 3 2007 Digi Key 16 40 1 9 2007 Linear Voltage Regulator 1 4 2007 Open Tip s e4 16 2007 lav Rechargable Battery 12212007 CACRONAME s1595 1292007 _ Devantech Speech Synthesizer _ 1 30 2007 Newark IN One wo shpo 441 27 2007 infrared LED Fairchild Semi Conductor vsoeo07_ ST OmegaEng saoo wsuzoo7 Gass insulated T C s5PK__ vooo pigikey gn 2 5 2007 Sensor Pressure Photodiode 2 xx2 8mm LED 3mm 2ns2007 Hargraves Fluidics 5747 2 22007 __ MicropumpE ZMount 2 13 2007 America RX com 17274 21 2007 Fingertip Pulse Oximeter 18700 ___ uid Power without shipping 37 60 2 26 2007 Parker Pneumatic Valve 43 93 a 3 30 2007 Homedics LED Digital Bathroom Scale aa ie eee Ge A7 Engineering 214 00 3 30 2007 ship pigikey sa mo _ icroc
27. onvert 11 this reading to digital data and send this result to the LCD display The analog pins used for analog inputs were ANO ANI AN2 AN3 and ANS After the voltage was read into the analog pins the corresponding digital number was used in calculating the correct number to be sent to the LCD screen The internal A D conveter does this using the following equation a 1024 Where 5V Vin Voltage input to ana log pin 5V reference voltage of SV 1024 number of bits in A D To configure the analog to digital converter the ADCONO and ADCON I registers were used The ACONO register controls the operation of the A D converter Each vital sign required its own A D conversion This was done by changing bits 5 3 as needed to select the appropriate input channel Also FOSC 32 was selected for the conversion clock The ADCONI register controls the function of the port pins Since all of our inputs were analog bits 3 0 were configured as 0000 allowing for all analog inputs Also the result of the A D conversion was right justified bit 7 Shown below is a sample of how the ANO pin was initialized for the body temperature void init_a2dtemp void ADCONO0 129 select Fosc 32 ANO A D on ADCON1 128 select right justify result ADON 1 turn on the A2D conversion module DelayMs 50 j 2 2 7 LCD Screen The digital information from the output of the microcontroller will be sent to a character LCD screen Fig 18
28. screens and buttons customized with Braille or Universal Symbols These features allow us to meet the needs of our clients with a device that is accessible to the hearing and visually impaired those with motor skills impairment and clients of all ages 25 5 References 1 Al Nashash Hasan Electrical Safety of Medical Equipment University of Sharjah School of Engineering lt http www ewh ieee org r8 uae Elect_ Safety Med Equip pdf gt 2 Basic Statistics About Home Health Care National Association for Home Care amp Hospice 2004 lt http www nahc org O4HC_Stats pdf gt 3 Blackfin Embedded Processor ADSP BF535 Analog Devices 2006 lt http www analog com UploadedFiles Data_Sheets ADSP BF535 pdf gt 4 Blood Pressure Monitor lt http www circuitcellar com fi2003 abstracts F 1 90abstract pdf gt 5 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 6 DeMarre Dean A and David Michaels Bioelectronic Measurements New Jersey Prentice Hall Inc 1983 7 Design and Engineering Toolless Plastic Solutions 2006 lt http www toolless com gt 8 Getting Started with Blackfin Processors Analog Devices 2006 lt http www analog com gt 9 Lineared NTC Thermistor eCircuit Center 2002 lt http www ecircuitcenter com Circuits therm_
29. temperature that correspond to inspiration and expiration By counting the number of inspiration and expiration pairs that occur in a given period of time we can determine respiratory rate Figure 14 Image of Thermocouple Nose Clip The respiratory rate probe itself was made with a two way 3 5mm retractable cable By pulling the jacks off each end of the cable one end was soldered to the thermocouple and the other end to a 3 32 phone plug The circuit for the thermocouple is powered by the battery The voltage from the thermocouple is linear over our range of interest approx 65 F to 98 F so the signal from the thermocouple only needs to be filtered and amplified before being A D converted and processed by the microprocessor The thermistor circuit uses the same low pass filter as the thermometer circuit Fig 15 v GND Th ermacaup le Figure 15 Circuit for Respiratory Rate As mentioned previously this circuit was calibrated experimentally Voltage output from the thermocouple was measured for inspiration and expiration Table 1 Table 1 Thermocouple Testing Data 10 S tate Vout thermocouple amp amplifier From these measurements the voltage threshold was set as 535V 2 2 5 Weight Weight is monitored through a commercial digital scale Homedics SC 202 Digital Scale that is connected to our device Determining to connect the scale to the monitor was done through experimentation Opening up the scale t
30. the SP03 to speak a line of text by sending it a sequence of commands Command byte Transmitted to SP03 Module Acknowledge b Command Ox80 0x0 SP03 will now speak the text 0x00 indicates text loading 1s complete _ Figure 20 SP03 Commands To send the SP03 a line of text a small subroutine had to written This subroutine programmed in C allows the microchip to send the SP03 text one character at a time To play these computer generated sounds a speaker was used 2 2 9 Secure Website After the client s vital signs have been gathered and recorded they need to be sent to their primary healthcare provider To maximize client privacy an encrypted password protected website is used to which the client can upload their vital signs 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 This website is currently being stored on the BME server An approved username and password are required to enter the site When access is granted the user is brought to a page where they can choose to upload any files on their computer Once the file s are uploaded they are saved to a database on the server The user can then download these files or leave the website A physician or remote healthcare provider can access these files through the same site sequence 13 2 2 10 Power Supply To power the mo
31. to the inside rear of the monitor Fig 32 Figure 32 Pulse Oximeter Mounted Inside the Monitor The pulse oximeter is accessed through a hole drilled in the top of the monitor To activate the pulse oximeter and measure blood oxygen saturation stick a finger in the rubber lined hole on the top of the monitor Fig 33 Figure 33 Pulse Oximeter in Use 2 3 3 Monitor Communications Upon power up the LCD screen displays a welcome message to the user Fig 34 which is echoed auditorally at the same time by a spoken message 18 leas i Figure 34 Welcome Message Display on the LCD Screen on Power up Vitals signs can be acquired in any order but they must be taken one at a time As each vital sign is being measured a message is displayed on the LCD screen indicating as such Fig 35 p Dian DENS Figure 35 Example of the Message Shown While the Monitor is Taking a Vital Sign Once the vital sign is acquired it is displayed on the LCD screen as well as spoken by the text to speech module through a speaker on the front of the monitor Fig 36 Figure 36 The Speaker is Mounted Inside the Front of the Monitor Behind the Speaker Holes in between the Two Buttons Once all or any of the vital signs have been measured pressing the red button sends them via Bluetooth to the computer The Bluetooth module within the monitor is activated as soon as the device is powered A phantom serial port connection is aut
32. us improvement to the project is the finished construction of a working prototype but as everything worked on the boards we expect that this would just require more time Aside from this an alarm system for dangerous vitals signs as described in the alternative design but never implemented would be an excellent addition to improve client safety and health As healthcare moves out of the hospital and into the home reliable technology for monitoring clients health is needed Vital signs monitors provide basic yet important information about a client s physical well being Unfortunately many of the vital signs monitoring systems available today are very expensive and inaccessible Most are designed for hospital use and have complicated interfaces that do not blend well with the home environment More devices are needed that are designed specifically for home use by clients their families and caregivers The accessible home vital signs monitoring system described in this report fulfills the need for an accessible user friendly home use vital signs monitor The simple 3 button design makes the device easy to use for all ages and abilities To provide comprehensive health care monitoring our device is designed to record the following six 6 vital signs body temperature blood oxygen saturation heart rate blood pressure weight and respiratory rate Accessibility is addressed through the speech module auditory and visual alarms large LCD
33. wo load cells were found at the rear corners The positive and negative outputs from these load cells were connected together at the same spot on the PCB Fig 16 Scale Remesentalion Bolio s E load cells Figure 16 Location of Load Cells in Scale Because the signal from the scale cannot be taken after it has been processed by the microprocessor within the scale it was taken from these two load cells The load cell signal was then processed through an instrumentation amplifier and filtered Fig 17 CND Figure 17 Scale Circuit Schematic The scale itself had already been calibrated and tested by its manufacturer but we still had to calibrate our scale the signal we are processing This was done by having lab members stand on the scale and comparing the voltage coming from our circuit to the weight displayed on the digital scale LCD in pounds The equation relating weight to voltage found by this was W 9000V 32374 where W is weight in pounds and Vo is the voltage out from the filter of the scale circuit 2 2 6 Microprocessor The main component of this system is Microchip PIC16F877 microprocessor shown below The PIC16F877 is a 40 pin 8 bit microcontroller that was chosen due to the fact that it is capable of processing every aspect of the monitor This chip is required to make every part of the monitor function Needing only 5V to power up the microprocessor was used to read the voltages sent to it by the probes c
34. y experienced a head injury from an automobile accident This accident has left the right side of her body paralyzed her dominant side Sani is a lawyer and is now working part time from home She must sleep in a hospital bed and she administers pain medication to herself using an infusion pump Her doctor monitors her vital signs by a computer system that is installed in her home Sani does not want to appear sick to her family 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 her grandson 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 1 2 Purpose of the Project The purpose of this project is to create an accessible home vital signs monitoring system Although there are already similar devices on the market it is our goal to design a monitoring system that meets our clients specific needs This device will improve our clients quality of life by allowing health care professionals to monitor them from home rather than from a bed in a hospital or nursing home Our c
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