ABSTRACT
Advanced sensors require both high sensitivity and wide applicability for various types of environment and systems. The recent paradigm change from conventional rigid electronics to flexible electronics urges sensors to be ultrathin and flexible in order to properly fit to the flexible round-shaped systems [1]. In terms of tactile sensing, most conventional sensors have relied on either capacitive or resistive touch methods using inorganic materials and/or metallic electrodes in the presence of polymeric films [2–5]. However, these sensors need direct physical touches for sensing so that they cannot detect an indirect stimulation such as very weak airflow changes induced by approaching objects. In this regard, we have introduced liquid crystals (LCs) as a sensing component because of their excellent collective properties (group behaviors) that enable ultrasensitive sensing [6,7]. As a signal transfer and amplification part in order to benefit the feature of LCs, organic field-effect transistors (OFETs) were employed because of their potentials for ultrathin and flexible device applications [8–34]. Combining LCs and OFETs gave birth to brand-new concept devices, LC-integrated-OFET (LC-i-OFET) devices, which can act as a tactile sensor and many more roles in the future.
