Electronic Subdermal Implant Tech
A few ideas or approaches for subdermal implantation of electronics I would like to discuss with you more experienced and critical people here.
By (physically) separating away the battery, charging coil and ~ circuitry from the control circuitry and the actual implant, the overall thickness of the implant can be drastically lowered (obviously at cost of the area). Ideally the power supply would be placed in a better accessible position than the implant that can accommodate for a larger implant. We however don't have technology for wires that span movable tissue, so there really aren't any places where this would work at the moment.
2. Bluetooth (4.0) Connectivity
Initially I was against the idea of implanting a Bluetooth module along a microprocessor, both because of relatively large energy drains and physical size of traditional modules.
The Bluetooth 4.0 "Low Energy" Standard (BLE/"Bluetooth smart") however solves both problems nicely, a TDI BLE module is just 4x5x1mm in size (including antenna!). The module is a QFN-package and more or less impossible to hand solder though (70 pins on less than an square centimeter iirc).
BLE is only set up for distances of about 10m and I don't know how bad RF-through-skin really is, but I do believe there should be some range (think mobile phone in pocket) left outside the body.
The Bluetooth 4.0 "Low Energy" Standard (BLE/"Bluetooth smart") however solves both problems nicely, a TDI BLE module is just 4x5x1mm in size (including antenna!). The module is a QFN-package and more or less impossible to hand solder though (70 pins on less than an square centimeter iirc).
BLE is only set up for distances of about 10m and I don't know how bad RF-through-skin really is, but I do believe there should be some range (think mobile phone in pocket) left outside the body.
Two other chipsets are the RFDuino and BlueRadios nBlue. The interesting part about both these is that they feature an on-board programmable microcontroller to do all the bluetooth stuff. The RFDuino can be programmed like a usual arduino, whilst the nBlue can only be programmed with a (very expensive) hardware debugger kit. However the nBlue features a lot of configuration options in the firmware, which even allow to set output pins of the package at runtime, over the air.
Why is this important? Well... one awesome feature of bluetooth would be being able to program the implant over the air. The RFDuino doesn't support this, and the nBlue (for us) doesn't really either, but both can be used to program another microcontroller. They just need to set the reset pin on the ATMega (or whatever really) and then forward the UART data they receive and we could have an OTA-programmable implant, that can even talk to smartphones.
3. Flexible PCBs and Coating
Flexible PCBs could be a great way to shrink size of implants and make larger ones possible at the same time.
By using SMD ICs and hardware on FPCBs and embedding these in flexible silicone, you could place implants in slightly bent areas (like the forearm) without creating extremely protruding implants.
Combine this with additional silicone to get a "cool" shape and you get a glowing arc reactor! (ok, agreeably there are better things to put this to work with).
So... what do you think?
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Comments
If all you want to do is to fold the pcb up to several layers, then it might be an option. But the saved volume is hardly worth it, compared to simply sandwiching regular thin pcb's. You'd need a mechanically rigid shell around the flex PCB,too.
And for casing, if you basically dip your design into slightly flexible silicone, wouldn't that work?
Either way, if a minuscule current draws less current than a vibration motor while providing an equal sense of 'feedback', this sounds like a much better approach!
As far as improving your "internal clock", having a small buzz every 1 hour would probably do it. enough to notice if you are awake, but not enough to wake you. then have a big buzz for the actual alarm you use. so that it can wake you up.
I believe this technology could be great inside most of implants making them pretty much independent from external charging and letting you worry a bit less about power drain.