Wearable devices, robotic skin and curved image sensors all need optoelectronic devices on surfaces that are not flat. Thinning a device makes it bendable but usually costs responsivity, and interconnects fail long before the active layer does. Separately, conventional image sensors digitise and transmit every pixel of every frame; in most applications the processor then throws almost all of it away.
On the first problem we use lateral NIPIN phototransistors, which keep their junctions in the plane of the film and therefore tolerate bending, and transfer printing to move finished devices onto flexible substrates. On the second we use ferroelectric-gated phototransistors that hold a weight in the pixel itself, so part of the processing happens where the light lands.
We also build the systems these devices go into, including a wireless, battery-free patch-type tissue oximeter that stays cool enough to wear outdoors by combining radiative cooling with the sensor.