Thermal effect of self assembled monolayer with the detection of piezoresistive microcantilever beam

• Main Authors: Yi-Hsuang Lin, 林宜璇
• Other Authors: Long-Sun Huang
• Format: Others
• Language: zh-TW
• Online Access: http://ndltd.ncl.edu.tw/handle/45675717714175583529

碩士 === 國立臺灣大學 === 應用力學研究所 === 96 === This work demonstrates the thermal effect of self assembled monolayer detected by piezoresistive micro-cantilever beam. The chemical monolayer of linker (HS-(CH2)7-COOH) was transported by microfluidics and self assembled onto the gold surface of the microcantilever beam. With the change of temperature applied by the external thermal source, the device signal was obtained by a single free-standing microcantilever beam of the sensor, which represented one varied resistance in the electrical resistance configuration of the Wheastone Bridge circuit. The experiment was carried out in successive thermal cycles of with and with no self-assembled monolayer. As described early, one single free-standing micorcantilever beam of the sensor was employed in this work instead of reported two free-standing beams for noise compensation due to flow-field, thermal, and chemical disturbance. In addition, the temperature sensor was made and embedded in the micro channel for measurement of temperature variation in thermal cycles. With no SAM coating, the averaged electrical signal with respect to temperature change was 0.0282 volts/℃、0.0214 volts/℃、0.0223 volts/℃ for three devices, respectively. In case of SAM coating onto the beam, the device signal apparently decreased to 0.0183 volts/℃、0.0173 volts/℃、0.0187 volts/℃, with respective to former three devices. It was found that the significant drops of three devices were 35.29 %、18.89 %、16.11 %. The monolayer of (HS-(CH2)7-COOH) is of less than 1 nm in thickness, self-assembled onto the microcantilever of approximate 1300 nm in thickness. This work has proven that the thermal property of such an extremely thin monolayer shows significant effect to the microcantilever beam.