Flexible IGZO thin-film transistors with liquid EGaln gate contacts

Flexible thin-film electronics leverage technological innovations in fields such as sensors, wearable Computing and healthcare. As these Systems are required to conform to non-planar surfaces, novel approaches are developed to provide stable performance under mechanical stress, and prevent crack formation. Liquid eutectic-Galn promises the realisation of self- healing, reconfigurable and bendable circuits. Here, a liquid EGaln-gate thin-film transistor is fabricated and characterised. The device yielded a carrier mobility of 7.9 cm 2 V –1 s –1 that increased by 0.36 cm 2 V 1 s –1 when bent to a 4 mm radius. These results promote the integration of highly deformable liquid materials into thin-film devices

Flexible sensors—from materials to applications

Flexible sensors have the potential to be seamlessly applied to soft and irregularly shaped surfaces such as the human skin or textile fabrics. This benefits conformability dependant applications including smart tattoos, artificial skins and soft robotics. Consequently, materials and structures for innovative flexible sensors, as well as their integration into systems, continue to be in the spotlight of research. This review outlines the current state of flexible sensor technologies and the impact of material developments on this field. Special attention is given to strain, temperature, chemical, light and electropotential sensors, as well as their respective applications

Fabrication, modeling, and evaluation of a digital output tilt sensor with conductive microspheres

Recent advances in wearable computing ask for bendable and conformable electronic circuits and sensors, allowing an easy integration into everyday life objects. Here, we present a novel flexible tilt sensor on plastic using conductive microspheres as gravity sensitive pendulum. The sensor provides a digital output of the measurement signal without the need for any additional electronics (e.g., amplifiers) close to the sensing structure. The sensor is fabricated on a free-standing polyimide foil with SU-8 photoresist defining the cavity for the pendulum. The pendulum consists of freely movable conductive microspheres which, depending on the sense of gravity, connect different electric contacts patterned on the polyimide foil. We develop a model of the sensor and identify the amount of microspheres as one of the key parameters in the sensor design, which influences the performance of the sensor. The presented tilt sensor with eight contacts achieves an angular resolution of 22.5° with a hysteresis of 10° and less at a tilt of the sensor plane of 50°. Analysis of the microsphere movements reveals a response time of the sensor at ~ 50 ms