When you're hitting a droplet with enough pulsed CO2 light to generate X-rays efficiently, you have to know exactly when it's going to cross the focus.
Producing an integrated model of circuit conditions and ion motion, allowing optimization of circuit and excitation parameters, plus sanity checking
In cooperation with Flatfrog Laboratories AB, Lund, Sweden. This one was interesting mostly due to the requirement for high and stable performance at an absolute rock-bottom cost.
This was a seedling design study for a DARPA program that never got funded. It leveraged POEMS and my antenna-coupled tunnel junction devices, adding a couple of novel wrinkles: metal-insulator-metal varactors and parametric readout using a 10 GHz pump frequency. Hopefully there will be a chance to revisit this, because it was potentially a pretty sweet solution.
For a large Far Eastern consumer electronics manufacturer to use in virtual reality games. A greatly improved transimpedance amplifier got them a factor of 10 in range (30 m vs. 3 m) for about the same amount of power.