Sensing Applications of Conformable Organic Imagers

Optical-based 3-axis pressure sensors, with delicate imaging systems, can offer detailed tactile pressure data vital for robotics and human interaction. However, their bulkiness complicates mounting and integra-tion. We present a thin and flexible sensor construction approach to realize detection of 3-axis pressure distribution on a large area with wide sensing range and high accuracy. The sensor can detect the distribution of 3-axis pressure on an area of 3 cm × 4 cm, with a high-accuracy normal and tangential pressure sensing up to 360 and 100 kPa, respectively. A porous rubber is used as a 3-axis pressure-sensitive optical modulator to omit the thick and rigid focusing system without sacrificing the sensitivity. In addition, by integrating thin and flexible backlight and imager, the sensor has a total thickness of 1.5 milimeter, making it function properly even when bent to a radius of 18 mm. The flexible imager uses a combination of organic photo diodes (OPDs) and low-temperature polycrystalline silicon (LTPS)–based thin-film transistors (TFTs) fabricated on a film substrate. The imager has a pixel size of 235 μm, and a total of 126 × 168 pixels are formed on a 3 cm × 4 cm area. The organic photodiode designed for NIR light detection, optimized for maximum sensitivity at a wavelength of 850 nm, exhibits excellent air stability due to the implementation of an inverted structure.