In device level, we pay attention to three research topics in recent years.
The first topic is the physical force sensor for robot applications. We implemented capacitive layouts, improved its detection sensitivity, spatial resolution, function of shear angle detection, accuracy, structural simplicity, design variation, and demonstrated multidisciplinary applications. Novel structures include asymmetric sensing unit, asymmetric electrode, vertical stack of capacitors, and polygon capacitors. This sensor is although considered a device when it is separated from signal processing, it supports sports science and health care when integrated with signal acquisition, remote control, and data server modules.
The second topic is the development of thermoresistive strain sensor, in which invisible force, stress, and strains are able to be visualized in three-dimensional (3D) profiles as a non-contact detection method. Successful examples include detections on various strains (tension and compression), directions (machine direction and transverse direction), and locations. By supplying additional concealing material, the detection sensitivity was improved; and by optimizing the design of thermoresistor, it supports detection in isotropic direction. When the thermal image (temperature) is linked to the strain database and converted to 3D axis, novel surface profiling is realized.
The third topic is the generation of nanophotonic structure to support various display applications, particularly in visible range. The first example is a wire-grid polarizer (WGP) used in liquid crystal display (LCD) panels. The WGP was fabricated by photolithography on plastic substrate, and its dimension is thus adjustable through mechanical forces. By stretching the substrate, the stress is transferred to WGP for different extents of width or pitch expansions. As a result, the transverse electric (TE) or transverse magnetic (TM) light component in LCD can be modified for tunable extinction ratio (ER). The second example is a microelectromechanical system (MEMS)-based color pixel, in which a hybrid structure and elastomeric material isotropically expand nanophotonic crystal array, changing its filtering colors from white to red, green, and blue based on corresponding strains. This realized full color display in one pixel in a time-sequential manner regardless of transmissive or reflective operation.
