Tasks/Accomplishments
This week was focused on researching the workings of BCI and looking for what could be potentially suitable parts for the project. I mainly focused on how we could get reliable electrodes that we could use for the project while not blowing up our budget. I began by looking at parts and costs from OpenBCI. However many of the parts or kits present were too expensive. Through some further research I was able to find the company that sources some of the parts for Open BCI and they provided more affordable options.
A good part, of my focus was on understanding the different types of electrodes available. The main two being cup electrodes and dry brush electrodes. Cup electrodes are the classic type which require a conductive gel to work properly and is often used in medical applications. Meanwhile dry brush electrodes are completely dry and have much easier setup. Technically the gold cups have a better chance for better signals but unless the dry brush completely fails we won’t use it.
The other major task this week was creating and sourcing the initial bill of materials for the analog acquisition hardware. I built a BOM with reference designator, value, manufacturer part number, unit cost, per-board quantity, total quantity, total cost, and purchasing link. I individually sourced the passive components, protection diodes, amplifiers, and trimmers rather than estimating a generic PCB cost. The current BOM contains parts such as the INA128UA instrumentation amplifier, OPA2227/OPA4227 op-amps, MMSD4448 protection diodes, precision resistors, filter capacitors, and adjustment potentiometers. For the quantities currently entered, the BOM totals approximately $228.35. This also gave us a much more concrete view of where the prototype budget is going and which components dominate cost.
More work needs to be done to see if replacements and cheaper options are available
Plans for Next Week
For next week we will be focused on drafting the first iteration of our PCBs and ordering parts, as well as trying again to contact professors with experience in the field.
On Schedule?
We are on schedule.