Direct writing of three-dimensional Cu-based thermal flow sensors using femtosecond laser-induced reduction of CuO nanoparticles. (5th April 2017)

• Record Type: Journal Article
• Authors: Arakane, S; Mizoshiri, M; Sakurai, J; Hata, S
• Is Part Of: Journal of micromechanics and microengineering. Volume 27:Number 5(2017:May)
• Publication Date: 2017-04-05
• Subjects: direct-writing -- femtosecond laser -- three-dimensional micromachined sensor -- thermal flow sensor -- laser-induced reduction -- CuO nanoparticle; Microelectromechanical systems -- Periodicals; Micromechanics -- Periodicals; 621.38105
• DOI: 10.1088/1361-6439/aa6820
• Languages: English
• ISSNs: 0960-1317

Abstract

Abstract: We have demonstrated the fabrication of two types of thermal flow sensors with Cu-rich and Cu2 O-rich microheaters using femtosecond laser-induced reduction of CuO nanoparticles. The microheaters in the shape of microbridge structures were formed to thermally isolate from the substrates by four layer-by-layer laminations of two-dimensional micropatterns. First, we evaluated the patterning properties such as dispensing coating conditions and degree of reduction for the selective fabrication of three-dimensional Cu-rich and Cu2 O-rich microstructures. Then, a hot-film flow sensor with a Cu-rich microheater and a calorimetric flow sensor with a Cu2 O-rich microheater were fabricated using their respective appropriate laser irradiation conditions. The hot-film sensor with the Cu-rich microbridge single heater enabled us to measure the flow rate in a wide range of 0–450 cc min −1 . Although a large temperature dependence of the Cu2 O-rich microbridge heaters caused a large error for the hot-film flow sensors with single heaters, they showed higher heat-resistance and generated heat with a lower drive power. The temperature coefficient of resistance of the Cu2 O-rich microstructures had a semiconductor-like large absolute value and was less than −4.6 × 10 −8 °C −1 . The higher temperature sensitivity of the Cu2 O-rich microstructures was useful for thermal detection. Based on these advantages, a calorimetric flow sensor composed of the Cu2 O-rich microbridge single heater and two Cu2 O-rich thermal detectors was proposed and fabricated. The calorimetric flow sensor was driven by a circuit for measuring the temperature difference. The Cu2 O-rich flow sensor could detect bi-directional flow with a small output error.