Community Project: Endochron
Anyone who would like to contribute feel free to add your thoughts here. If you need to make purchases to support your contribution to the project, see this thread , and direct message @amal or @Satur9 with details. Project threads can get a little out of hand with tons of people brainstorming. I ask that you limit your messages to the topic at hand. Try to condense multiple messages into one post.
This community project has been ongoing for awhile but the part sourcing has been a huge hurdle. The current goal is to use surface mount betavoltaic cells to power a semi-permanent internal clock with a red LED 7-segment display.
Unfortunately the biggest hurdle is actually getting your hands on suitable betavoltaic cells. A few companies like CityLabs and Widetronix offer surface mount versions of their products. The problem has been actually getting them to talk with you, and the large upfront capital investment. Fortunately, Widetronix has optimized their production to the point that medium batches of custom SKUs are plausible.
I am in contact with Chris Thomas (CEO of Widetronix) and I am working through the process of getting a surface mount package produced. The output is abysmally small, but for an implantable clock where the LEDs are only lit for a second a few times a day it should be doable based on our calculations. Here are some of the specs on the proposed unit:
- 12 years half life of tritium
- 8mm x 8mm x 2mm package dimensions
- 2uW output (3.8V at 526nA)
Even if you don’t particularly care about the implantable clock use-case, these betavoltaics will become available for other biohacking projects. The current plan is:
- NTAG 5 acting as a transparent I2C master bridge between the phone and a low power MCU+RTC combo
- Betavoltaic cell (possibly several in parallel) trickle charging a capacitor bank (possibly regulated by a zener diode). The energy harvesting on the NFC chip can top up the capacitor bank if needed.
- Surface mount 7-segment display hooked up to MCU to display clock digits sequentially (lower power version could use single indicator LED with binary clock)
Some next steps are:
- Source appropriate low power MCU+RTC combo
- Acquire radioisotope license (Satur9 working through that process)