Bicycle Powered MRI


MRI stands for Magnetic Resonance Imaging. So, the SpokePOV uses a Magnet to measure wheel rotation, and derives the Resonant frame rate by timing Magnet readings, and then it makes the Image appear, as if by some kind of circular magic, on the bicycle wheel! Thank you Adafruit, for this super cool toy! I use it to make legit brain-scan on a bike! I made two images of brains and fine-tuned in the SpokePOV software. The SpokePOV software is not very sophisticated, but it is Sunday after all, and I have a bottle of Lillet and an orange.

Just so you can see the POWER of SpokePOV, I’m putting screen-grabs from the software head to head with pictures I took of my wheel spinning in my apartment. To take the picture, I used my iPhone4 with the LongExpoFree app in the LightTrail setting.



















Not bad! I think the first one looks more like cauliflower. The second one is a cross-section (s l i c e !) I like the slice better.

The reason for this velodrome vivisection is that I am finally booked for the DARPA EEG thing. The ongoing direct contractual process is removed from me, thankfully, but I did get a PO this week from the lead company and have already begun work. The hardware will be built around Texas Instruments ADS1299 which is, in so many ways, an EEG system-on-a-chip. There will be lots more details to come, but the best part is that it allows very fine control of the metal. You get gain control, all the channel inputs are thoroughly multiplexed, high common-mode rejection, and simultaneous sampling. The interface sits on a high-speed SPI bus. It is a very sensitive sensor! It will be great for reading EEG, but that’s not all. EMG and ECG and other biopotentials are easy pickings. Any really really tiny electric potential can be measured by this thing. The chip has Eight separate channels that can be measured separately, or in relation to each other. Simultaneously. And, you can daisy-chain multiple chips together to get more channels. HA!

All of the designs and firmware will be open source and the initial focus will be on Arduino compatibility. You may have noticed that we are living through multiple revolutions at once, and one of them is The Open Hardware Movement which has leveraged the design and spirit of Arduino into a Mass Movement of Makers. The ‘footprint’ of Arduino is widely mimicked by Shields (add on boards, or daughter cards) and other devices wishing to play in the Arduino space. Happily enough, a few ARMs are now available with the same Arduino form factor. I’m planning libraries for the DUE, Maple, FreedomBoard, and others that cross my path.

As this thing moves forward, I’ll have a more structured interface for comments/suggestions/spam. Until then, please be patient in waiting a response. Or just email me, I’m not hard to find.

This is not a one man show. I am grateful to have some very talented friends. Thanks to Luke, my summer intern/slave. And Conor of the Brain Interface Lab, my go-to-BCI-guy.

Let the Summer of Brains begin!

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