Nano thermal sensors for sensing temperature in water environment

In this paper we illustrate the fabrication process of nano temperature sensors using focused ion beam chemical vapor deposition (FIB-CVD) of tungsten over atomic force microscope (AFM) cantilevers, to be used in sensing temperature distribution in local area. We present the fabrication approach & modifications for making these sensors capable of sensing temperature distributions not only in air but in water environment as well. The nano sensor was calibrated in water using the hot stage of the environmental scanning electron microscope (ESEM). The experimental results show the positive characteristics of the temperature coefficient of resistance (TCR). We also illustrate the response of the sensor to sudden changes in the surrounding medium. The characteristics of this sensor were compared to previously reported temperature sensing devices. The comparison verifies that our sensor is relatively uncomplicated and reliable in fabrication. The capability of sensing temperature in water will allow our sensor to be used in wide range of bio-applications, especially in studying thermogenesis in single cells.