[Ray] likes to build all sorts of Propeller-based projects, but one of the more interesting items we came across was this DIY ECG. While we have covered other DIY electrocardiograms before, he left the breadboard behind and put together a nicely done PCB for his build.

The ECGs design should be pretty familiar to anyone that has seen our ECG coverage in the past. The user places his thumbs on the large built-in pads, which allow the circuit to sense the electrical signals produced by heart’s contractions. These small electrical impulses are then amplified using an AD627 instrument amplifier before being further amplified via a dual op-amp.

The amplified signal is filtered and then fed into the Propeller’s ADC, which displays the user’s heart rhythms via an LED. The data can also be fed into a computer via an optoisolated serial connection.

[Ray] lays out a litany of warnings and precautions that should be followed before downloading his schematics and firmware. We have to echo those warnings, as it doesn’t take a large well-placed shock to disrupt the heart.

This module is a sensor package for monitoring the electrical activity of the heart. It is the product of an effort to create a Wireless Body Sensor Network node that is dependable while consuming very little electricity, which means a longer battery life. To accomplish this, the microcontroller in charge of the node compresses the data (not usually done with wireless ECG hardware) so that the radio transmissions are as short and infrequent as possible.

[Igor] sent us this tip and had a short question and answer session with one of the developers. It seems they are working with the MSP430 chips right now because of their low power consumption. Unfortunately those chips still draw a high load when transmitting so future revisions will utilize an alternative.

Oh, and why the iPhone? The device that displays the data makes little difference. In this case they’re transmitting via Bluetooth for a real-time display (seen in the video after the break). This could be used for a wide variety of devices, or monitored remotely via the Internet.

When we saw [merkz] use of an Arduino to produce lucid dreaming we were quite shocked. Unlike typical setups that just flash a light through sleep, his system monitors eye movement through electrodes and is able to send the data to a computer for graphing and analyzing.  The only problem being we couldn’t find a circuit diagram or code.

Not ones to be shot down so quickly, a Google revealed this thread on making ‘Dream Goggles’, which was really a Brain-Wave Machine based on the parallel port. Some modifications of an ECG collector’s electrodes using sound cards, and you could have your own lucid dreaming.

[Thanks Phil]

Although we’ve covered DIY ECGs before, [Scott Harden] sent in his version that gives an in-depth explanation of what to do with the collected data. He built a basic battery-powered op-amp-based ECG for under $1. The circuit just amplifies the signal from the chest leads and feeds it into a computer via the microphone port. He then used GoldWave to record, filter, and save the signal. From there, he used python to analyze the heartbeat and calculate his heart rate and further manipulate the data. His previous blog posts go into more detail on how the python code works and why he chose software over hardware filters.