New micro-thermometer to record tiny temperature changes

Thermometer for nanoscale measurements.

(a) Video still showing a tightly focused laser beam making contact with the thermocouple. (b) Graph showing the thermocouple's response over time to different laser powers (3.6 and 1.8 mW) at different repetition rates, on glass and on the silicon nitride membrane (ΔT: change in temperature, τ: time for temperature rise and decay)
(a) Video still showing a tightly focused laser beam making contact with the thermocouple. (b) Graph showing the thermocouple's response over time to different laser powers (3.6 and 1.8 mW) at different repetition rates, on glass and on the silicon nitride membrane (ΔT: change in temperature, τ: time for temperature rise and decay). CREDIT Scientific Reports

Scientists at Tokyo Institute of Technology (Tokyo Tech) have recently developed a micro-thermometer can measure small and rapid temperature changes in real time. This device consists of a gold and nickel thermocouple on a silicon nitride membrane and is miniaturized to the extent that the electrodes are only 2.5 μm wide and the membrane is just 30 nm thick.

There is an urgent need for a device that can measure thermal behavior on the nanoscale in real time. So, scientists developed this technology that is sensitive enough to heat generated by optical and electron beams. According to scientists, the applications for the device include, to explore heat transport on the micro- and nano-scales, and in optical microscopy and synchrotron radiation experiments. It could also be applied in photo-thermal cancer treatment as well as in advanced research on crystals, optical light harvesting, etc.

A thermocouple is an electrical device comprising two divergent electrical channels shaping electrical intersections at varying temperatures. A thermocouple creates a temperature-subordinate voltage, which can be translated to gauge temperature. The smaller scale thermocouple as of late created by researchers at Tokyo Institute of Technology and their partners is of real significance to scientists in numerous fields.

The device can also be used as a thermal characterization device, i.e., a thermometer, it must show sensitivity to temperature change. The developed micro-thermocouple exhibited high responsiveness to heat generated by a laser and an electron beam. Imperatively, modest temperature changes were estimated by the created thermocouple for the two kinds of warming.

In order to enhance the sensitivity of the device, scientists established a method, a cross pattern of metal stripes with widths of a few micrometers and produced a thermocouple. Through this approach, a thermometer that could measure fast and small temperature changes were successfully produced, with the measurements being performed through the nano-thin silicon nitride membrane.

Scientists noted that the system can be regarded as a new “toolbox” for investigating heat transport behavior on the micro- and nano-scales, with many important applications in a wide range of fields.

Their findings are reported in the journal Scientific Reports.