Note: A scanning thermal probe microscope that operates in liquids

We have developed a scanning thermal probe microscope that operates in liquid environments. The thermal sensor is a fluorescent particle glued at the end of a sharp tungsten tip. Since light emission is a strongly thermally sensitive effect, the measurement of the particle fluorescence variations allows the determination of the temperature. No electrical wiring of the probe is needed. As a demonstrative example, we have measured the temperature map of a Joule-heated microheater immersed in a water∕glycerol solution. Both topographical and thermal images are obtained with a good sensitivity.