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We developed a tunable wedge prism by electrowetting actuation. Our prism can shift the field of view to the left or to the right and is useful for small cameras and endoscopes because its field of view can be changed without the need for large instruments. It consists of two plates that face each other, and a liquid is sandwiched between them. The liquid and plates form a wedge when the angle between the plates is changed. We used electrowetting to change the angle between the plates. The wedge prism is small because the liquid driven by electrowetting works as a prism. In addition, the prism produces a clear field of view because its optical flatness is determined by the flatness of the plates. [ABSTRACT FROM AUTHOR]

This paper reports on the development of a micro electro mechanical system microphone consisting of a piezoresistive cantilever and a micro HR (Helmholtz resonator) for use as an ultrasonic proximity sensor. The resonance frequency of the HR was designed to be equal to that of the cantilever. Therefore, the HR increases the sensitivity of the microphone to ultrasonic waves. The dimensions of the fabricated HR and the cantilever are 1.2 mm × 1.2 mm × 0.6 mm and 130 &mgr;m × 40&mgr;m × 0.3 &mgr;m, respectively. At a resonance frequency of 22.6 kHz, the cantilever with the HR detected ultrasonic waves with 14 times greater sensitivity than that of the cantilever without the HR. We demonstrated that the fabricated sensor is capable of measuring distances between 0.5 and 6.0 m. [ABSTRACT FROM AUTHOR]

Abstract: We have developed a silicon-microfabrication-based surface plasmon resonance (SPR) sensor with Si prisms and an optical grating. Since this sensor is compatible with microelectromechanical systems technology, it can be further miniaturized and integrated with optical parts or fluidic components for the realization of a one-chip SPR sensor. The Si prism structure, transparent in the near-infrared range, was used to lead the 1550-nm measuring light to the sensing surface where the evanescent light was generated. Smooth prism slopes were obtained by using anisotropic etching to utilize the (111) planes on the (100) surface plane of single-crystalline Si wafer. The result was a 200-μm-pitch array of prisms with 54.74° slope angles. In this configuration the range of incident angles at which near-infrared light produces an SPR dip is from 38.26° to 71.24°. Because the SPR angles for major specimens (16.60° for air, 22.06° for water, and 22.79° for ethanol) are out of range, we used an optical grating with a roughly 400-nm-pitch to make an SPR dip position move to fit within the available angle range by the diffraction effect. SPR measurements with several specimens confirmed that the combination of Si prisms and the optical grating excited surface plasmons. The measured SPR dip positions and their sensitivity to refractive index were compared with the theoretical values, and their consistency confirmed the utility of this device as an SPR sensor. [Copyright &y& Elsevier]