Ultra-low-power polymer thin film encapsulated carbon nanotube thermal sensors

A novel polymer thin film embedded carbon nanotube (PECNT) sensor was developed for ultra-low-power micro thermal sensing. The basic fabrication process of this sensor includes AC electrophoretic manipulation of multi-walled carbon nanotubes (MWNT) bundles on a silicon substrate and embedding them inside parylene C layers to provide a robust protection for the bundled MWNTs. This encapsulation process ensures that the MWNT elements can be protected from moisture and contaminates in an operational environment, and thus, allows the sensors to be useful for potential applications such as temperature measurement in water, sensing human touch and body temperature, or as ultra-sensitive sensors in manufacturing plants. The I-V measurements of the resulting devices revealed that their power consumption was in the μW range, which is 3 orders of magnitudes lowered than polysilicon sensors and can be operated at over 20 V. Besides, the frequency response of the testing devices was generally over 100 kHz in constant current mode operation. Moreover, from the results of resistance stability measurement, our PECNT sensors remained stable for over at least 20 hours. Based on these experimental evidences, carbon nanotube is a promising material for fabricating ultra-low-power consumption and high frequency response micro sensors for future thermal sensing applications.