MEMS thermoelecctric multi-color photo-thermal detector

The photothermal effect is the most direct and simple way to use solar energy. Different color materials have different thermal effects under light exposure, which will have wide range of influences on people’s daily life, such as the production of clothing and the choice of paint. This article innovatively proposes a way of using MEMS micro-thermoelectric generator (μ-TEG) to distinguish the photothermal effect of different materials after exposure to light. The design and manufacture of MEMS μ-TEG is the focus of this paper, in which the micro-nano manufacturing technologies such as ultraviolet lithography and magnetron sputtering are mainly used. A hybrid fabrication method combining the non-contact lithography and photoresist melting is used to prepare a top electrode with good electrical contact. In the 5 cm*5 cm area, we integrated 46000 P-N thermoelectric units in series on a silicon wafer and its ultra-thin structure offers very high temperature sensitivity. In our experiment, by changing the substrate materials’ type and color, the light-to-heat effects were studied under monochromatic LED light illumination. The results demonstrated that the difference of the photothermal effects can be used to distinguish the various materials. The experimental samples include cotton, linen, chemical fiber, and paper. Each material includes red, yellow, green, and white. For each sample, ultraviolet/visible/near infrared spectrophotometer was used to measure the absorptivity in the visible light range. At room temperature (298K) and in an enclosed test platform (to minimize air flow), the open circuit voltage of 1~2 mV can be detected by the irradiation of monochromatic LED light source, which can accurately measure and distinguish samples of different colors and materials. It has broad application prospects in the field of photothermal effect temperature measurement and reaction process temperature monitoring.