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VitaMon Low-Cost Critical Health Monitoring System

In developing countries, it is difficult to provide adequate monitoring services to the critically ill as hospitals are understaffed and cannot afford expensive monitoring systems. This project focuses on developing a portable, wearable device with low-power processing and sensing capabilities that can monitor and record vital patient signs (specifically EKG, temperature, and galvanic skin response) in order to take the place of direct human monitoring. In the event that a patient's vital signs indicate an emergency (examples include the heart rate dropping below a certain rate, temperature above/below accepted norms, and hyper-ventilation and/or shock as indicated by the GSR sensor), the monitoring device can sound an alarm to alert the attention of medical staff. The device can also record the patient's vital signs onto local storage on the wearable monitor, which can be reviewed by a doctor at a later point.

Here is the ThinkCycle Topic that I started for low-cost biometric monitoring systems, which I encourage people to contribute to if they are interested in the topic. The main platform that I used for the data acquisition for the monitor was the Hoarder board platform developed by Vadim Gerasimov. The platform is meant to be designed as a flexible, lightweight data acquisition system used for a variety of applications. The platform consists of a 20Mhz PIC16F877 microcontroller, compact flash CF slot (for up to a gigabyte of non-volatile storage), serial port, and runs on 4 AAA batteries and has a daughter board connector to interface with sensor boards. To the baseboard system described above, I added a wireless tranceiver module to allow the board to communicate data with a computer via a 900 Mhz signal. The SAK/hoarder baseboard is interfaced with a biometric daughterboard which does the appropriate filtering/amplification/leveling circuitry for the temperature, ekg, and galvanic skin response sensors. Here are the schematics for the circuit design, PCB design and assembly photos, and sensor-leads assembly.

The entire module was attached to a custom chassis that was cut using the laser cutter, attached to velcro straps, and put into a custom vacuum-formed case. with holes that were put in to accommodate the lead connector, and an external switch which was attached.

The completed critical healthcare monitor is pictured here from various angles:

This small, wearable health monitor was wirelessly interfaced to a program on a laptop, which can display a real-time graph of a ekg waveform, galvanic skin response level, and temperature (a great deal of the code to do this was graciously provided by Vadim). The program is set up such that an alarm sounds when the following conditions arise:

1) The heartbeat rate falls below 50 bbm (beats per minute) or goes above 120 bbm.

2) The temperature goes below 90 degrees or above 99 degrees.

3) The galvanic skin response level suddenly ramps up past a threshold over a sampled baseline value in a specified time interval.

The VitaMon wearable monitor is a proof-of-concept device that can allow ambulatory remote healthcare monitoring. Here's a screenshot of the system in action, with the EKG waveform (red), galvanic skin level (yellow line toward the bottom), and temperature/pulse/gsr level information (in the upper left corner) all visible as the data from the wearable monitor is streamed in real-time to the laptop:

We can imagine adding a more powerful processor (the current PIC is just about completely loaded recording and transmitting the biometric data) so that we can do more sophisticated real-time analyses on the received biometric data. For example, an embedded algorithm which can detect heart arrhythmias in the EKG waveform and trigger an alarm, etc.

A special thanks is given to Vadim Gerasimov, for providing me with schematics, PCB boards/parts, code, as well as his general help and invaluable explanations, which I leveraged a great deal of when putting together the system..

Human Dynamics Group | MIT Media Lab |