Biopotential

2 Articles

Self-Driving Or Mind Control? Which Do You Prefer?

May 24, 2021 by 9 Comments

We know you love a good biohack as much as we do, so we thought you would like [Tony’s] brainwave-controlled RC truck. Instead of building his own electroencephalogram (EEG), he thought he would use NeuroSky’s MindWave. EEGs are pretty complex, multi-frequency waves that require some fairly sophisticated circuitry and even more sophisticated signal processing to interpret. So, [Tony] thought it would be nice to off-load a bit of that heavy-lifting, and luckily for him, the MindWave headset is fairly hacker-friendly.

EEGs are a very active area of research, so some of the finer details of the signal are still being debated. However, It appears that attention can be quantified by measuring alpha waves which are EEG content between 8-10 Hz. And it seems as though eye blinks can be picked from the EEG as well. Conveniently, the MindWave exports these energy levels to an accompanying smartphone application which [Tony] then links to his Arduino over Bluetooth using the ever-so-popular HC-05 module.

To control the car, he utilized the existing remote control instead of making his own. Like most people, [Tony] thought about hooking up the Arduino pins to the buttons on the remote control, thereby bypassing the physical buttons, but he noticed the buttons were a bit smaller than he was comfortable soldering to and he didn’t want to risk damaging the circuit board. [Tony’s] RC truck has a pistol grip transmitter, which inspired a slightly different approach. He mounted the servo onto the controller’s wheel mechanism, allowing him to control the direction of the truck by rotating the wheel using the servo. He then fashioned another servo onto the transmitter such that the servo could depress the throttle when it rotates. We thought that was a pretty nifty workaround.

Cool project, [Tony]! We’ve seen some cool EEG Hackaday Prize entries before. Maybe this could be the next big one.

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Hackaday Prize Entry: Biopotential Signal Library

May 22, 2015 by 11 Comments

With prosthetics, EEG, and all the other builds focused on the body and medicine for this year’s Hackaday Prize, it might be a good idea to take a look at what it takes to measure the tiny electrical signals that come from the human body. Measuring brain waves or heartbeats indoors is hard; AC power frequencies easily couple to the high impedance inputs for these measurements, and the signals themselves are very, very weak. For his entry to The Hackaday Prize, [Paul Stoffregen] is building the tools to make EEG, ECG, and EMG measurements easy with cheap tools.

If the name [Stoffregen] sounds familiar, it’s because he’s the guy behind the Teensy family of microcontroller boards and several dozen extremely popular libraries for everything from displays to real time clocks. The biopotential signal library continues in [Paul]’s tradition of building very cool stuff with just code.

The hardware used in this project is TI’s ADS1294, a 24-bit ADC with either 4 or 8 channels. This chip is marketed as a medical analog front end with a little bit of ECG thrown in for good measure. [Paul] is only using the ADS1294 initially; more analog chips can be added later. It’s a great project in its own right, and when you include the potential applications of this library – everything from prosthetics to body sensors – it makes for an awesome Hackaday Prize entry.

The 2015 Hackaday Prize is sponsored by: