OLIMEXINO-NANO-EKG is open source shield based on the OpenEEG project. It gets attached over the main board OLIMEXINO-NANO, expanding its functionality with the ability to perform electrocardiogram.
There are several home ECG systems, these appear to cost over $150 USD and only provide a single ECG trace which is measured between finger tips
The finger tip measurement is prone to muscle action noise from the action of holding. They also are unable to monitor over a long period when the user is performing normal daily tasks.
A home ECG may show early warning signs and prompt a user to a formal check from a doctor.
Rare or occasional heart events can also be captured over the day and print outs could be taken to a doctor.
Several other open projects for ECGs were found however none found could be purchased.
Develop a device which can provide good quality home ECG measurement for less than 60EUR. The following functions would be present:
- 3 wire measurement
- Logging data for a full day (24 hour)
- Lipo battery powered with enough charge to properly operate for 24 hours
- Able to charge via USB
- Able to transfer logged data transfer over USB
- Flashing LED during each pulse for user feedback
- Small size that allows the system to be wearable
- Wireless connection option (bluetooth) for real time monitoring using a phone/tablet
- Blood oxygenation measurement option. Potential logging to help diagnose sleep apnia issues
TI app note existing olimex ECG shield is based on
ECG primer, ECG wave form and identified conditions explained in detail
wiki for ECG
Existing ECG developed under an Open license
non contact ECG
ECG with ads1298
MobilECG Open Source 12 leads design
Current Actions and Progress
- Tested the existing shield-EKG-EMG - Found gain works well however noise from power systems presented on the output even when battery powered and with the 40hz and above filter. This means a design based on the existing system would rely on software to isolate and remove 50,60hz noise
- test of shielded probes to reduce 50,60hz interference - Using shielded wire on all probes with the shield connected to the ref voltage found noise was removed when connecting the left and right arm probe together. However when connecting to the body the overall noise pick up on the body negated the affect.
- A prototype board has been designed and is being manufactured. The board intends to test
- 3 measurement trace circuit compared to existing 1 measurement trace
- isolation methods. Noise reduction strategy and isolation for protection will be tested
- A concept to reduce 50,60hz noise using right leg drive method which injects a signal to counteract noise
- A different type of instrumentation amp on the front end of the analogue section to see if it reduces noise
- Power test to check for likely battery needs
- Check performance of a less complex and smaller reference voltage circuit
- Investigating methods to reduce mains frequency interference (50,60hz). Testing has shown and several reports of noise present in shield-EKG-EMG
- Alternative probe options, IE option to use probes to stick to skin