A printed proximity-sensing surface based on organic pyroelectric sensors and organic thin-film transistor electronics

Large-area, flexible proximity-sensing surfaces are useful in a range of applications including process control, work security and robotics. However, current systems typically require rigid and thick electronics, which limit how they can be used. Here we report a flexible large-area proximity-sensing surface fabricated using printed organic materials and incorporating analogue front-end electronics in each pixel. The sensing surface is built with printed thin-film pyroelectric sensors based on poly(vinylidene fluoride-co-trifluoroethylene) co-polymers and printed organic thin-film transistors. A 5 × 10 matrix frontplane, consisting of long-wavelength infrared organic pyroelectric sensors, is laminated with an organic transistor analogue front-end backplane. The electronic front end provides sensor-signal amplification and pixel addressing to maximize the detection distance and reduce pixel crosstalk. An average yield of 82% fully working pixels for the backplane and a maximum system yield of 96%, which corresponds to 768 defect-free devices, are achieved. The system can detect a human hand approaching from different directions and track the position of a movable heat source up to a distance of around 0.4 m at a readout speed of 100 frames per second. A sensing surface fabricated from printed thin-film pyroelectric sensors and printed organic thin-film transistor technology can be used for human proximity detection.