Jie Chen

Second Prize; Advisor: Jae-Hyun Ryou
Ph.D. student in Mechanical Engineering; "Flexible Piezoelectric Generators & Pulse Sensors using Single-Crystalline III-N Thin Film"


Abstract: The flexible piezoelectric generator (F-PEG) and the flexible piezoelectric pulse sensor (F-PPS) were developed with single-crystalline group III-nitride (III-N) thin film, by transferring the as-grown thin film from the Si (111) substrate to a foreign flexible substrate. A large area and defect free flexible single-crystalline III-N thin film was obtained by this layer-transfer method. The III-N thin-film F-PEG can generate an open-circuit voltage of 50 V, a short-circuit current of 15 µA and a maximum power of 167 µW with a corresponding optimum load resistance of 5 MΩ. The III-N thin-film F-PEG is able to directly power electronics such as light-emitting diodes and electric watches, and charge commercial capacitors and batteries. The III-N thin-film F-PPS is sensitive enough to convert the subtle deflection caused by the arterial pulse into electrical signal and detect the pulse waveform with detailed characteristic peaks from most arterial pulse sites. Both the F-PEG and the F-PPS showed high durability and stable outputs after being subjected to long-term tests. The flexible piezoelectric devices made from single-crystalline III-N thin films have great potential applications in future flexible wearable electronics, such as the energy harvesters and passive pulse sensors.