Micromachined piezoelectric microphone with high signal to noise ratio

Abstract

This study reports a novel electrostatic vertical comb-drive micro-actuator (VCA) driven by the photovoltaic effect that results from the incident light. The vertical comb electrodes are composed of pn-junction structures (named PN-combs). The VCA with PN-combs can be driven by the photovoltaic effect and/or reverse electrical bias. The VCA with PN-combs was fabricated on an epitaxial silicon wafer and successfully driven by intensity-modulated laser light and reverse bias. The combination of the photovoltaic effect and reverse bias can further increase the mechanical scan angle of the VCA. Experiments demonstrate the feasibility of four driving methods, including optical driving, optical driving with DC reverse bias, electrical driving and electrical driving with DC photovoltaic voltage. KEYWORDSvertical comb-drive actuator, photovoltaic effect, electrostatic actuator.

Miniature Ultrasonic and Tactile Sensors for Dexterous Robot

“…Piezoelectric-type microsensors have several advantages: they are simple structures; they have a simple fabrication process because, unlike the capacitive-type, a narrow gap structure is not required; and they potentially have lower power-consumption owing to their nature of self energyconversion [14] than the capacitive-and piezoresistive-types. Here, the diaphragm-type piezoelectric ultrasonic microsensors is described [15].…”

Highly sensitive structures for ultrasonic microsensors by buckling control of diaphragms through intrinsic stress of PZT films

“…Microfabricated ultrasonic sensors for these applications have been increasingly investigated in a capacitive type [1], [2] and a piezoelectric type [3], [4]. Owing to its nature of self-generating charge, the piezoelectric microsensors have advantages [5] such that no need of biasing voltage and simple readout circuit, low cost with easy microfabrication process, especially being freed from sticking issue because of backplate-less configuration, and potential to fully batteryless operation with energy harvesting nature. The authors have been developing piezoelectric diaphragm-type ultrasonic microsensors [6] and that of a silicon dioxide-diaphragm type [7], [8] is illustrated in Fig.…”

Buckling control of silicon dioxide diaphragms by lateral stress enhancement for sensitivity improvement of piezoelectric ultrasonic microsensors

“…Microfabricated ultrasonic sensors have been realized on cantilevers and diaphragms using detection principle of capacitive [1][2][3], piezoresistive [4,5] and piezoelectric [6][7][8] sensing technique. Piezoelectric-type microsensors have advantages from the viewpoints of simple structure and simple fabrication process because no narrow gap structure is required over the capacitive-type, and potentially low power-consumption owing to self energy-conversion nature [9] over the capacitive-and piezoresistive-type. The authors have developed diaphragm-type piezoelectric ultrasonic microsensors [10].…”