The Need For SEPARATE Metal Films on the Front and Back of NPN Chips
It has been a constant theme in our EO efforts as well as our energy harvesting efforts that our electrodes need to be as close as possible to the surface to see an effect. In Jess’s early EO work, we found that our chips could be used as EO pumps that were vastly more thermodynamically efficient than any other existing tech, but that we still only had efficiencies of less than 0.01%. Jess’s electrodes were roughly 1 cm apart, and the forces involved should scale as r^2, so you can imagine that reducing the electrode distance from 1 cm to 50 nm (6 orders of magnitude) would have a dramatic effect on the ratio of field strength across the pores to applied voltage across the electrodes.
Further, our ultrasound efforts (which are still somewhat speculative) would also see a massive efficiency boost from surface electrodes. If we could make a chip that looked like this:
Where the yellow film represents metal of some kind
It could be used for:
- Efficient EO
- Flow detection/energy harvesting (an EO pump run in reverse)
- Ultrasound generation
- Ultrasound detection
The problem with making this chip is 2 fold:
First, we need to be sure that the metal does not enter the pores (the film is electrically continuious across the surface, and discontinuous across the chip.
Second, we need a way to get charge down to the backside of the membrane, which is complicated because of the overhang left by one of the etching steps.