A Novel Film Thermal Converter Based on an Electrothermally Excited/Piezoresistively Detected Microbridge Resonator

This paper presents the design, fabrication, and preliminary results of a resonant thermal converter consisting of an electrothermally excited/piezoresistively detected SiO ₂ /Si ₃ N ₄ /Si _x N _y microbridge resonator and a Ni _24.9 Cr _72.5 Si _2.6 heating resistor placed on another beam parallel to the microbridge. The noncontact temperature sensing technique reduces the diversion of thermal energy from the temperature sensors, as well as the ac–dc transfer differences due to the capacitive coupling between the heater and the temperature sensor. The semidigital output of the resonant thin-film thermal converter eliminates problems such as intensity fluctuations associated with analog signals. The temperature coefficient of resistance of the Ni _24.9 Cr _72.5 Si _2.6 film with a thickness of 89 nm is only $-0.86 \times 10^{-6}$ /K. The responsivity of the resonant thermal converter is $9.21~\text {kHz}\cdot \text {W}^{-1}$ in air. The thermoelectric transfer difference measured by the fast-reversed dc method at 1 kHz is $2.8 \times 10^{-6}$ . It indicates that the resonant thermal converter is a promising thermal converter.