I went to an open day in October run by the mind people, makers of the Vilistus EEG interface. It was an opportunity to see this in action and ask questions – the day was £85 which wasn’t too bad, there were about five other people there. It was run in some anonymous hotel near a football ground in Birmingham just off the M6, and led by Stephen Clark who knew the product well.
It was an interesting day, the Vilistus 4 box is a digitising interface but analogue signal conditioning is done in the sensor boxes, which add some cost to the overall system. Their default software looks fine even for Mind Mirror since it seems to have the filter bank in it, the extra costs for the Mind mirror package probably involves extra training. You seem to get the vilistus pro software with the box. I haven’t seen any of the units come up on Ebay.
I learned that the interface between the Vilistus interface and the computer is OpenEEG P3, which was good to know, and Stephen did warn that a lot of the older OpenEEG code from the OpenEEG project made the assumption that there were only 6 active slots rather than following the protocol specification which allowed the source to say whether there are 6 or 8 slots of data. Vilistus use 8 slots, so code assuming 6 would barf.
He did say the existing API would allow the Vilistus Pro software to continually dump the values of the filter slots to a text file that could be read by a program to display the output on LEDs, obviously I would get to build the interface and write the program 😉
The Vilistus Pro software did show correlations well – most clearly on a display where they showed heart rate against a trigger for breathing in and out. The heart rate slows a teeny bit on breathing out relative to breathing in, although this effect fades with age – it was clear on the 25 year old student and not really visible on a 50-something lady on the course. EEG was tough to get going in the course, although it was demonstrated using disposable electrodes on the forehead. This isn’t the optimal placement for Mind mirror but you can’t use disposable electrodes on areas of the scalp covered by hair.
The trouble is this rig would be about £1200 all in, and I’m not yet sure I am £1200 interested in the Mind Mirror. I did get a much better feel for using this in the field, and I’m aware that while I have been able to solve the digitising side of things using the PIC, I still need to solve the EEG diff amp, and solve the electrode problem.
Vilistus seem to have solved a lot of that, but even the electrode set is ~£200, so the bundle would be the way to go. One to mull over really, to work out whether I want the functionality or the engineering challenge. I could probably knock off £500 going DIY if the development went OK, but experience shows only one to two PCB fails or wrong turns can wipe out the savings on a one-off project where there’s a COTS solution.
One to think about. The Olimex EEG-SMT and 4 electrodes is about Euro100 – okay so it has the iffy antialiasing filter but a £1100 saving has its attractions 😉