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{{Health}}
=The US$10 TeleHealth Module=
* This low cost, multifunction peripheral will provide a means through which the XO can relay valuable medical diagnostic data from the field to doctors many kilometers away.
* Good documentation needed, possibly via svg/javascript animations.
* It will compose of a three lead EKG providing valuable information about the heart's electrical status, enabling diagnosis of congenital defects and various arrhythmias.
* It will also contain a multipurpose NIR diagnosis tool whose primary function is that of a pulse oximeter, providing information about the oxygen saturation of the blood.
** See nirdiagnositics.com for other NIR functions
* The long, time consuming parts
** Getting approval from governmental and medical organizations.
** Providing an intuitive interface and a pictograph manual.
** Drivers, integration with [[Measure]], and construction of a usable [[TeleHealth Database]].


= Sensors =
== 3 Electrode EKG ==
== [[Health_Hardware/ECG|EKG]] ==
* How to do it
** The first part is the actual hardware part. A circuit, possibly USB powered, using op-amps, would amplify the signal received by the sensor array(of three to twelve electrodes in contact with the skin, in proximity to the heart), to a voltage usable by an ADC. Hospital telemetry units typically use five-lead arrays and derive the standard 12-lead EKG. For diagnostics, the ability to produce a twelve-lead EKG would be infinitely preferable because this is what doctors are trained to read. There should also be at-the-point-of-need instructions for where to place each lead.
** The second part is the safety part, due to the proximity to the heart, strict regulation of leakage current is needed.
** The third part is adapt [[Measure]] to increase functionality as a [[Telemedicine]] platform.


Simple 3 lead EKG for arrhythmia and trauma diagnosis. Also facilitates pedagogical exercises into
*Implementation
** Multiple Op-Amps pick up, amplify, and filter electrical impulses picked up by near-heart electrodes.
*** Older EKGs used suction based reusable electrodes, an adaption of these may be best suited for the third world where replacements are scarce.
** DyD/DyDisMe has schematics for an EKG using AD620A style op-amps.
*** 4.1044-7.3 usd
** Ram Dhurjaty, a medical device professional who has had substantial experience with EKG amplifiers, has pointed suggested that there are better amplifiers than the AD620.
** Dirakx(Rafael Ortiz) is currently in the prototyping phase of an EKG, to incorporate into the THM, as of Nov. 14th of 2007


*Four parts:
== NIR Diagnosis Aid ==
** Connection: Electrodes connecting device to person
* Based on the principles of the differences in absorption of oxygenated and non oxygenated hemoglobin
** Amplification: Multiplies the voltage of the heart's electrical signal into something computer-usable
* 800-1000nm light from LEDs are often used in NIR tools
** Opto-Isolation: Protection circuits
** The most cited frequencies for IR Pulse Oximetery include 805nm, 910nm, and 940nm.
** 940nm IR LED; 12.2c per unit
** USB ADC: Inputs data to the XO
* Red light is generated from similar LEDs.
** 10-20c per unit
* Light is picked up by photodiodes, converted to current.
* This current is amplified and converted to voltage by a [http://media.maxim-ic.com/images/qv/3760.gif MAX4006] or equivalent chip
** 1.275 usd


*Main Chipset : The AD8541/2/4 series op-amps fulfill the target specs perfectly.
==Stethoscope==
The stethoscope was invented in 1816 by Rene Laennec to avoid having to place his ear to a woman's chest to listen to her heart. Improvements were made in terms of convenience, by adding tubing instead of using a solid wooden trumpet design, but the stethoscope has not changed much since it was invented.


Today, electronic stethoscopes are becoming more common, gradually supplanting the conventional stethoscope. The electronic stethoscope provides amplification and filtering, and facilitates connection to external devices for recording and transmitting heart and lung sounds. This is convenient for record-keeping of auscultation findings, and for remote auscultation of heart sounds and lung sounds.


=== Target Specs ===
An example of a modern electronic stethoscope with such a connection is the Thinklabs ds32a stethoscope. This device can connect to laptop computers, as well as iPods and other recorders. By connecting a stethoscope to a laptop or notebook computer, and transmitting sounds, clinics can be set up im remote places for examination of children by a pediatric cardiologist to differentiate between innocent and pathological murmurs.
*Low frequency: -3 db @ 0.1 Hz
*High frequency: -3 db @ 45 Hz
*Patient leakage current: <10 µA with acquisition module connected (meets AAMI standard SCL 1278)
*Chassis leakage current: <100 µA (meets AAMI standard SCL 1278)
*Common mode rejection: 130 dB minimum with balanced leads. With 5Kohm imbalance 100dB


*A/D conversion: 10-12 bits
Here's an [http://nielsolson.us/MedSchool/stethophone.html example of a electronic stethoscope] that can be built with any stethoscope head, a piece of tubing and a lapel microphone. This particular version uses a battery, but a similar device should be able to draw power from a USB port. The signal is fairly clean, you can hear breath sounds and about halfway through you can hear a playmate giggle in the background, but the signal does require substantial amplification.
*Impedance: 100 Mohm, defibrillator-protected (optional for the XO)
*Signal Dynamic range: 10 mV
*Electrode offset tolerance: + - 320 mV dc (this is due to the fact the electrodes get polarized)


*[http://wiki.laptop.org/go/Image:EKG.JPG EKG Schematic] Tentative design similar to the above specs
Suggestion: Too much "signal" is probably being lost due to the stethescope head itself. [http://medical-equipment-news.absolutemed.com/2007/09/mp3-recorderplayer-could-replace.html Another bit of research] being done involves using a "cheap" mp3 recorder, pressed directly to the patients chest, to record breath and heart sounds. What about using just small housing around the lapel mike, pressed against the chest? (or indeed, the XO itself?)
*[http://wiki.laptop.org/go/Image:Protoboard.JPG EKG Circuit] A photo of the initial circuit.


== ADC/DAC ==
=== Status ===
* Current problems include tuning op-amps and prototyping.
* C8051F321 or equivalent chip
* Determine efficient alternatives to the classical electrodes.
** A/D 5x10b minimum
* As a side note the signal must be AM modulated before going to the XO, because some low frecuency components of the EKG signal are filtered by the card, so modulation implies also demodulation on the PC side, in this case some kind of python script must do the trick.
** This specific chip provides A/D 13x10b
* Alternatively a USB micro-controller may communicate with dedicated ADC/DAC chips via PWM, to lower cost.
* Honza Kovar(Jan), from the Czech republic, has acquired development board for the C8051F321 MCU, and will assist with programming and development.


== Pulse Oximeter ==
==THDB==
An invaluable piece of medical equipment relaying information about pulse and oxygen saturation by analyzing the output of two filtered photo-diodes in two different frequencies. The pulse oximeter operates on the theory that oxygenated and deoxygenated hemoglobin have different absorption and reflection frequencies. The same principle can be applied to any other small organic molecule with identifiable spectra, with proper calibration.
* [[TeleHealth Database]]
=== Hardware ===
'''Currently nonfunctional''' design consists of a AD854x operational amplifier with supporting passive components connected to a photodiode. A red and IR Led are driven by the MCU alternately. The data from the photodiode will be transmitted to the XO and collated, where, after calibration, it will provide information in both graphical waveforms and numerical statistics.


* Main Chipset: AD854x Op-Amp(same as used in the EKG)
== Contributors ==
* Ian Daniher
* Ram Dhurjaty (Simple concept suggested elsewhere)
* Rafael Ortiz
* Steve Burns
* [[User:Sethwoodworth|Seth Woodworth]] (isforinsects)


==Resources==
=== Links ===
* Electronics links:
* http://www.olpcnews.com/use_cases/community/medical_application_community.html
** Micro-controller-hobbyist-built pulse oximeter: http://tinkerish.com/blog/?p=166
* http://openeeg.sourceforge.net/doc/links-biopsy.html
** PO Box, another hobbyist oximeter: http://www.youritronics.com/po-box-just-another-oximeter/
* http://library.med.utah.edu/kw/ecg/
*** PDF abstract http://www.circuitcellar.com/microchip2007/winners/DE/abstracts/MT2278_Abstract.pdf
* http://www.uneca.org/itca/healthport/discussions.htm
*** Project documentation, theory, and code http://www.circuitcellar.com/microchip2007/winners/DE/entries/MT2278.zip
*[http://www.thinklabsmedical.com stethoscope]Thinklabs electronic stethoscope for connection to laptop computers.
** Academic theory and construction of a pulse oximeter: http://www.ett.co.th/product/robot/tcs230/App_525_proj2.pdf
*[http://swikis.ddo.jp/WorldStethoscope/ World Stethoscope] A universal appliance to get real-time environment data into [[Etoys]]. The original World Stethoscope converts sensor data into sound which is read via a computer's microphone input (hence the name). We intend to use the World Stethoscope's Etoy user interface with the OLPC XO's AD-converter directly.
** Analog Devices case study on oximeter using ADuC7024 microconverter: http://www.analog.com/library/analogdialogue/archives/41-01/pulse_oximeter.html
** Block diagrams for TI's pulse oximeter hardware: http://focus.ti.com/docs/solution/folders/print/330.html
* Theory / medical links
** Theory on Pulse Oximeter: http://courses.cs.tamu.edu/rgutier/cpsc483_s04/pulse_oximetry_notes.pdf
** More pulse oximetry theory: http://www.ph.surrey.ac.uk/~phs3ps/surj/v2/li.pdf
* Misc
** How to read an oximeter (appears normal air O2 level is high 90s) http://www.ehow.com/how_2075144_read-pulse-oximeter.html


** http://pulsesensor.com/ opensource heart rate sensor project
== See also ==
* [[:Category:Health]]
* [[Vision screening]]


== Stethoscope ==
[[Category:Hardware ideas]]
A simple microphone and audio amplifier to pick up heart, lung and bowel sounds.

=== Hardware ===
* Button Mic
* Audio amplifier
* Shielded twisted-pair cable
* Mic plug

=== Status ===
* Requirements Identification

== Thermometer ==
A small temperature monitor with accuracy of plus or minus half a degree Celsius will, with calibration, provide information about the body's natural temperature fluxes as well as alerting a monitoring individual to dangerous extremes.

=== Hardware ===
* MCP9700A Temperature Monitor in TO-92.
* Non-insulative casing for probe.
=== Status ===
* Prototyping

= MCU + ADC =
* The Atmel ATtiny461 is likely going to be used. The chip has been prioritized over the PIC18F4553 due to pricing, features, and programming. As Atmel Chips have excellent documentation, a FOSS toolchain, and a fantastic community, design should be fairly straight-forward and easy.
* The '461 provides the following:
** 10x10b ADC
** 20 pin DIP
** 4KB of Flash Memory
* Design / Programming goals
** Total of 7 digital outputs; 1 IR LED, 1 Red LED, and 5 Indicator LEDs
** More than 6 analog inputs, voltage input ranging from 0-5v
** 3 digital inputs for buttons allowing allowing secondary control
** Real-time reading and control of analog and digital I/O via USB/PyUSB
** Minimize number of unused pins / maximize hackability.
==Brain Dump==
*att461
**drives Red LED and IR LED at mid frequency (120+hz)
**powered straight from USB with smoothing capacitor and fuse
**reads amplified photodiode signal(analog)
***photodiode signal amplified via AD854n schematic in datasheet
**reads EKG signal or controls sound card input(for higher accuracy)
***EKG amplified using AD854n as well
***Controls soundcard input via FET?
***EKG using [http://www.eng.utah.edu/~jnguyen/ecg/instructions.html|Home Made Electrocardiogram] until AD854n design is finished(summer)
**constantly monitoring
***Pulse Ox - software side user detection
***Thermometer - starts recording when temp > 33 degrees Celcius
**push button monitoring of EKG
**drives the following digital I/O
***as many green LEDs as inputs(for good signal/monitoring indication)
***one red LED(for warning signal)
***one button(for EKG control)
*IO/MCU paradigms
*Pick one from each of the following columns
==ADC==
*I2C 12/14b
*10b ADC on MCU
*Fake ADC using resistor matrix&digital inputs
==Communication==
*software USB (read AVR-USB)
*hardware USB (read AT90USB)
*USB-Serial chip (read Prolific or FTDI)

* [[User:Mchua]] will likely be handling the [[/Programming]].

= Power Supply =
Due to the nature of medical instrumentation as necessitating high-precision power supply, some combination of a regulator chip, fuse, and smoothing capacitor are needed.
If the power supply of the circuit is connected to the electrical net, this has to be carefully isolated form the electrical connections that provide the biomedical signals. A bad isolation can put the patient at risk for electrical shock.

== Hardware ==
* Main Chipset: LP2982
* LP2982 5, 4.5, or 3v regulator
* Over-voltage protector
** Fuse
* USB Connector
* Shielding

= Get Involved =

Your help is very welcome in this project. If you would like to participate in the [[Health Jam]] in Seattle around early April we are looking for organizers and participants. Contact [[User:DyD|Ian Daniher]] if you're interested.

=== Help wanted ===

* Provide talent, time, or treasure:
** If you have experience designing medical instrumentation, and are willing to mentor or assist high school age students...
** If you have extra time and are able to send emails, track down sample components, or raise awareness...
** If you don't know what to do with your old soldering iron, oscilloscope, or components collection...
* Program! We're in need of interested Python programmers.
* Provide expertise! Provide a critique of the procedure and component selection outlined above. We can always use an extra head, especially if you have '''any''' experience in the fields of telehealth or telemedicine
* Come to the [[Health Jam]] in Seattle, or help us plan it.

=== Parts needed to start developing ===

If you want to contribute to hardware or firmware design, you'll need the following to get started.

* [http://spreadsheets.google.com/ccc?key=p9ze5UJZKyDt-1dNy5P2tCg&hl=en Pre-Alpha BOM]
* PIC Programmer

== People ==

''' Warning - below information is obsolete. I [Ian] will update it soonly. '''
--[[User:DyD|DyD]] 19:50, 13 January 2010 (UTC)

[[User:DyD | Ian Daniher]] has been working on designing (and learning everything needed to design) a TeleHealth Module for several months. He is doing parts selection, circuit design and layout, and general coordination type things.

[[User:Mchua | Mel Chua]] is the firmware coder

[[User:Sethwoodworth | Seth Woodworth]] was the man on the ground in Seattle getting resources organized for the [[Health Jam]]

== Similar Projects ==
* http://www.eng.utah.edu/~jnguyen/ecg/ecg_index.html
* http://reza.net/cms/index.php?page=HealthMonitor
* http://www.thinkcycle.org/tc-notes/?topic_id=39823
* http://web.media.mit.edu/~msung/vitamon.php
* http://www.kmitl.ac.th/~kswichit%20/

== External links ==
* http://olpcgoldenstate.blogspot.com/


[[Category:Health]]
[[Category:Hardware]]
[[Category:Hardware]]
[[Category:Peripherals]]
[[Category:Peripherals]]

[[Category:Health]]
== P.S. and random thoughts ==
[[Category:Feedback]]
* Optimize design for low part count, reducing complexity, allowing for field repair.
* Multipurpose chips? Potentially share op-amps between EKG and Pulse ox.
* Water and sterilizer proof case - allow for submersion in alcohol to sterilize?
* Rather than "all in one" ADC and USB MCU, perhaps use low cost attiny2* with a dedicated ADC chip? Increases code complexity, perhaps, but results in lower BOM?

[[Category:Measure]]

Latest revision as of 05:40, 28 September 2011

  This page is part of the OLPC Health Project. Hardware | Software | Content | Health Jam
XO Caudecus

Sensors

EKG

Simple 3 lead EKG for arrhythmia and trauma diagnosis. Also facilitates pedagogical exercises into

  • Four parts:
    • Connection: Electrodes connecting device to person
    • Amplification: Multiplies the voltage of the heart's electrical signal into something computer-usable
    • Opto-Isolation: Protection circuits
    • USB ADC: Inputs data to the XO
  • Main Chipset : The AD8541/2/4 series op-amps fulfill the target specs perfectly.


Target Specs

  • Low frequency: -3 db @ 0.1 Hz
  • High frequency: -3 db @ 45 Hz
  • Patient leakage current: <10 µA with acquisition module connected (meets AAMI standard SCL 1278)
  • Chassis leakage current: <100 µA (meets AAMI standard SCL 1278)
  • Common mode rejection: 130 dB minimum with balanced leads. With 5Kohm imbalance 100dB
  • A/D conversion: 10-12 bits
  • Impedance: 100 Mohm, defibrillator-protected (optional for the XO)
  • Signal Dynamic range: 10 mV
  • Electrode offset tolerance: + - 320 mV dc (this is due to the fact the electrodes get polarized)

Status

  • Current problems include tuning op-amps and prototyping.
  • Determine efficient alternatives to the classical electrodes.
  • As a side note the signal must be AM modulated before going to the XO, because some low frecuency components of the EKG signal are filtered by the card, so modulation implies also demodulation on the PC side, in this case some kind of python script must do the trick.

Pulse Oximeter

An invaluable piece of medical equipment relaying information about pulse and oxygen saturation by analyzing the output of two filtered photo-diodes in two different frequencies. The pulse oximeter operates on the theory that oxygenated and deoxygenated hemoglobin have different absorption and reflection frequencies. The same principle can be applied to any other small organic molecule with identifiable spectra, with proper calibration.

Hardware

Currently nonfunctional design consists of a AD854x operational amplifier with supporting passive components connected to a photodiode. A red and IR Led are driven by the MCU alternately. The data from the photodiode will be transmitted to the XO and collated, where, after calibration, it will provide information in both graphical waveforms and numerical statistics.

  • Main Chipset: AD854x Op-Amp(same as used in the EKG)

Links

Stethoscope

A simple microphone and audio amplifier to pick up heart, lung and bowel sounds.

Hardware

  • Button Mic
  • Audio amplifier
  • Shielded twisted-pair cable
  • Mic plug

Status

  • Requirements Identification

Thermometer

A small temperature monitor with accuracy of plus or minus half a degree Celsius will, with calibration, provide information about the body's natural temperature fluxes as well as alerting a monitoring individual to dangerous extremes.

Hardware

  • MCP9700A Temperature Monitor in TO-92.
  • Non-insulative casing for probe.

Status

  • Prototyping

MCU + ADC

  • The Atmel ATtiny461 is likely going to be used. The chip has been prioritized over the PIC18F4553 due to pricing, features, and programming. As Atmel Chips have excellent documentation, a FOSS toolchain, and a fantastic community, design should be fairly straight-forward and easy.
  • The '461 provides the following:
    • 10x10b ADC
    • 20 pin DIP
    • 4KB of Flash Memory
  • Design / Programming goals
    • Total of 7 digital outputs; 1 IR LED, 1 Red LED, and 5 Indicator LEDs
    • More than 6 analog inputs, voltage input ranging from 0-5v
    • 3 digital inputs for buttons allowing allowing secondary control
    • Real-time reading and control of analog and digital I/O via USB/PyUSB
    • Minimize number of unused pins / maximize hackability.

Brain Dump

  • att461
    • drives Red LED and IR LED at mid frequency (120+hz)
    • powered straight from USB with smoothing capacitor and fuse
    • reads amplified photodiode signal(analog)
      • photodiode signal amplified via AD854n schematic in datasheet
    • reads EKG signal or controls sound card input(for higher accuracy)
      • EKG amplified using AD854n as well
      • Controls soundcard input via FET?
      • EKG using Made Electrocardiogram until AD854n design is finished(summer)
    • constantly monitoring
      • Pulse Ox - software side user detection
      • Thermometer - starts recording when temp > 33 degrees Celcius
    • push button monitoring of EKG
    • drives the following digital I/O
      • as many green LEDs as inputs(for good signal/monitoring indication)
      • one red LED(for warning signal)
      • one button(for EKG control)
  • IO/MCU paradigms
  • Pick one from each of the following columns

ADC

  • I2C 12/14b
  • 10b ADC on MCU
  • Fake ADC using resistor matrix&digital inputs

Communication

  • software USB (read AVR-USB)
  • hardware USB (read AT90USB)
  • USB-Serial chip (read Prolific or FTDI)

Power Supply

Due to the nature of medical instrumentation as necessitating high-precision power supply, some combination of a regulator chip, fuse, and smoothing capacitor are needed. If the power supply of the circuit is connected to the electrical net, this has to be carefully isolated form the electrical connections that provide the biomedical signals. A bad isolation can put the patient at risk for electrical shock.

Hardware

  • Main Chipset: LP2982
  • LP2982 5, 4.5, or 3v regulator
  • Over-voltage protector
    • Fuse
  • USB Connector
  • Shielding

Get Involved

Your help is very welcome in this project. If you would like to participate in the Health Jam in Seattle around early April we are looking for organizers and participants. Contact Ian Daniher if you're interested.

Help wanted

  • Provide talent, time, or treasure:
    • If you have experience designing medical instrumentation, and are willing to mentor or assist high school age students...
    • If you have extra time and are able to send emails, track down sample components, or raise awareness...
    • If you don't know what to do with your old soldering iron, oscilloscope, or components collection...
  • Program! We're in need of interested Python programmers.
  • Provide expertise! Provide a critique of the procedure and component selection outlined above. We can always use an extra head, especially if you have any experience in the fields of telehealth or telemedicine
  • Come to the Health Jam in Seattle, or help us plan it.

Parts needed to start developing

If you want to contribute to hardware or firmware design, you'll need the following to get started.

People

Warning - below information is obsolete. I [Ian] will update it soonly. --DyD 19:50, 13 January 2010 (UTC)

Ian Daniher has been working on designing (and learning everything needed to design) a TeleHealth Module for several months. He is doing parts selection, circuit design and layout, and general coordination type things.

Mel Chua is the firmware coder

Seth Woodworth was the man on the ground in Seattle getting resources organized for the Health Jam

Similar Projects

External links

P.S. and random thoughts

  • Optimize design for low part count, reducing complexity, allowing for field repair.
  • Multipurpose chips? Potentially share op-amps between EKG and Pulse ox.
  • Water and sterilizer proof case - allow for submersion in alcohol to sterilize?
  • Rather than "all in one" ADC and USB MCU, perhaps use low cost attiny2* with a dedicated ADC chip? Increases code complexity, perhaps, but results in lower BOM?
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