기계 공학부 구성원들의 많은 관심과 참여 부탁 드립니다.

▣ 제   목: Beyond mass sensing with microchannel resonators

▣ 연   사: 이정철 교수

▣ 소   속: KAIST

▣ 일   시: 2021. 12. 3.(금) 16:00

▣ 장   소: 제4공학관 D403호

▣ 초   청: 김종백 교수

▣ 초   록

Microchannel cantilevers, one of promising physical microelectromechanical systems (MEMS) devices that have embedded microchannels, have been widely used in gravimetric sensing applications of liquids and particles introduced into the channel or dispensing/patterning applications with liquid phase materials when a dispensing nozzle is additionally configured near their free ends. Although there are numerous potential applications at elevated temperatures such as material synthesis, calorimetric measurements, and phase change mediated manipulation or control, to name a few, microchannel cantilevers are mostly used at or near room temperature mainly due to the absence of integrated active heating elements. Towards various applications under fast and quantitative temperature modulation, we have developed fluidic resonators with integrated heating capability. First, a stainless steel tube resonator was made by simply clamping a straight stainless steel tube on CNC-machined jigs along with piezoelectric chips. The stainless-steel tube resonator under Joule heating was successfully employed for boiling point measurements of water. After the proof-of-concept study with the stainless-steel tube resonator, we have switched to microfabricated channel resonators with an integrated heater for sensitivity enhancement. Heater-integrated microchannel cantilevers with or without a dispensing nozzle were batch-fabricated via sacrificial process, ion implantation, and other typical microfabrication processes. Fabricated heater-integrated microchannel cantilevers were thoroughly calibrated and characterized in a variety of coupled physical domains. Upon pulsed operations, electrothermomechanical time constants extracted from the transient resonance frequency provided a new measurement modality for thermophysical properties of the fluid contained in the microchannel. When a glycerol-water binary mixture was pulsed heated above its boiling point, atomized droplets could be spray-ejected out of the integrated nozzle.