The DC Stim

The DC Stim is a medical device designed to provide three levels of regulated direct current for direct current therapies; particularly, the DC Stim has been designed for safe and easy-to-use tDCS applications. Generally, because of cultural bias (fears of media exagerated electroshock therapy and ubiquitous pharmaceutical inroads), people are comfortable ingesting powerful drugs that may have nasty side effects but are very hesitant about applying a small current to their brain! Hence the functioning of the DC Stim was carefully considered to minimize confusion and maximize success. Some of the main functions and features of the DC Stim:

• Three levels of regulated current (1.0mA, 1.5mA, and 2.0mA) selected with a simple slide switch on the front panel.
• A fourth position of the switch to a "Test" position, that will shine an LED when the resistance between the electrodes is low enough for the device to function properly (<10kohms)
• A ramp up and ramp down to minimize discomfort on turn on and turn off.
• A short circuit protection so the output will turn off if the electrodes are shorted together.
• A battery indicator when the two nine volt batteries need to be replaced.
• Small, easy-to-carry unit
• Retail price (when it finally can be sold) of $250 (including electrodes)

I have built a breadboard device (see below) that I use on myself, and eager friends, and I am currently designing the PCB for the manufactured prototype.

I was hoping to do a small run with crowdfunding money but the project was rejected by Techmoola. I have designed the whole unit with off the shelf parts in mind (no large up front engineering costs) hence I am planning now to build 2 - 5 devices to validate all the features and begin the safety testing. Another aim is to submit for IEC 60601 medical equipment safety certificate as a first step to sell abroad as the FDA process of regulating tDCS devices does not look imminent.

Above are two pictures of the breadboard model, of course the manufactured prototype will be all professional looking with fancy membrane switches and a low profile front panel.

I hope to have it complete, built, and tested in less than two months from today. Fingers crossed.

For those technically interested the design is based around switching in particular valued current regulating diodes (with all the safety features added) and is not microprocessor based. This keeps the cost down, but also I feel it is a more robust design (but I would say that since I definitely lean more as a hardware engineer). Keep looking at this blogpost, I plan on publishing the core regulating design.