Tsuneji Yada

Static Characteristics of Piezoelectric Thin Film Buckling Actuator

We have developed a diaphragm piezoelectric microactuator. The diaphragm consists of a Pb(Zr, Ti)O3 (PZT) thin film, electrode layers, an isolation layer and a Si substrate. The diaphragm is deflected by transverse stress in the PZT thin film which is fabricated by a sputtering and annealing process. The PZT thin film has a piezoelectric coefficient d31 of -100 pC/N, which is comparable to that of bulk PZT. A diaphragm deflection of 3 µ m was obtained at an electric field of 16 V/µm.

PZT thin-film actuator driven micro optical scanning sensor by 3D integration of optical and mechanical devices

In this paper, a novel functional element integration method is proposed and demonstrated by highly miniaturized micro optical scanning sensor with dimensions of W2.0/spl times/L4.0/spl times/H2.8 mm/sup 3/. In the sensor as small as a wheat grain, the functional elements such as a laser diode (LD), photo detectors (PDs), a beam splitter, a ball lens, and a PZT thin-film actuator integrated optical scanner are integrated on separate substrates each consisting a functional module and the substrates are stacked. And the sensor is capable of multi-optical sensing: the 2D object shape recognition (+/- 10 degs scanning area for two direction) and the range measurement (50 mm +/- 10 mm with 0.5 mm resolution).

The 2-dimensional micro scanner integrated with PZT thin film actuator

The new silicon micromachined optical scanner integrated with a PZT thin film actuator has been developed for a super miniaturized scanning type optical sensor. The scanner driven by the PZT thin film microactuator is able to scan a light beam in two directions with a scanning angle of 4.7 degree. The size of the scanner is 2 mm/spl times/4 mm/spl times/0.4 mm. The design of the scanner used the design method including air damping consideration. The measurement value of the resonant frequency was in good agreement with the calculated value using this design method. This design method is useful to predict the dynamic characteristics of a microminiaturized scanner integrated with a PZT thin film actuator.

Sputtered high |d/sub 31/| coefficient PZT thin film for microactuators

High |d/sub 31/| coefficient PZT thin film for Si-based microactuators has been developed. Piezoelectric coefficient d/sub 31/ of around -100 pC/N was obtained and it is comparable to that of thick film or bulk PZT. The film was deposited on Pt/Ti/LTO/Si substrate by magnetron sputtering and annealed for obtaining perovskite structure. It was made clear that a <111> strongly oriented film has a higher |d/sub 31/| coefficient. Crystal orientation preference was controlled by ramp rate at post anneal process. Built-in stress and Youngs modulus of PZT thin film have also been evaluated. It was shown that post anneal process significantly increases both mechanical characteristics. 10 minutes-annealed PZT thin film which has d/sub 31/ of -100 pC/N has a built-in stress of 380 MPa and a Youngs modulus of 75 GPa.

Pb-based ferroelectric thin film actuator for optical applications

Novel PZT thin film actuators for optical applications were proposed. Key issues for realizing the actuators such as PZT thin film processes, mechanical properties evaluation of thin films, and design for laminated structure were described. [1 1 1]-oriented PZT films were obtained by anneal/non-anneal sputtering process. Also for PZT dry etching, it was made clear low pressure and low temperature conditions were advantageous for high selectivity and etch rate. ECR etcher was used and etch rate of 1000 A/min and selectivity of 0.56 to photoresist mask were obtained. Young’s modulus and built-in stress of PZT film, measured by load-deflection method, were 72 GPa, −335 MPa respectively. Using these results, calculated deflection of each actuator was on the order of a few microns to 20 microns. It was confirmed that deflection of actuators would be enough for the application.

Two-dimensional miniature optical-scanning sensor with silicon micromachined scanning mirror

For achieving higher performance and for miniaturizing the size of an optical scanning sensor, raising the scanning angle response, increasing the accuracy of detection of the scanning location independent from the environmental temperature, and miniaturizing an optical-scanning sensor were considered. And the silicon micromachined 2D optical scanner integrated with a piezoresistor for scanning location detection and a photodiode for optical intensity detection was newly designed and fabricated. The obtained results with the fabricated scanner are following. The scanner is capable of scanning a light beam more than 40 degrees 2D. The scanning angle sensitivities are 4.8 deg/V for horizontal direction and 10.5 deg/V for vertical direction. The scanning location detection sensitivity for each horizontal and vertical directions are 21 mV/deg and 26 mV/deg., respectively. The decrease of detection accuracy of scanning location has been reduced to less than 1 percent within +/- 10 degrees C temperature shift. And the photodetector has a photosensitivity of 0.33 A/W which allows the optical-scanning sensor to detect the reflected light intensity from an object which is 200 mm away from the sensor.

Micro Mixer Incorporated with Piezoelectrially Driven Valveless Micropump

Micro mixer using turbulence principle was first reported. The turbulence occurred from the work of valveless micropump. Liquids were mixed in a chamber with oscillating diaphragm driven by PZT at high frequency. The mixer had a layout of 2 pairs of diffusers on the inlet and outlet of the chamber, respectively. All those diffusers were in the size of 1.5 mm long and had an angle of 5°. The diaphragm was in the size of 6 mm x 6 mm x 0.15 mm. The mixing chamber was in the same length and width of diaphragm and had a depth of 0.04 mm. A piece of bulk PZT (5 mm × 4 mm × 0.2 mm) was glued onto the diaphragm. As a pump, it worked until 10 kHz when a square wave voltage (120V peak-to-peak) was used for the excitation. The maximum output was found to be 15.6 μl/min of the maximum flow rate and 2.16 kPa of the zero flow pressure using 870 Hz square excitation wave to drive ethanol. To test the properties of the mixer, different pigments were added into water, methanol and ethanol, respectively. The color changes were observed when water mixed with ethanol and methanol mixed with ethanol.

Miniature optical scanning range sensor utilizing a silicon micromachined scanner

This paper describes a miniature optical scanning range sensor based on a newly proposed detecting method using a Si micromachined optical scanner for detecting the range to a target plane. This sensor consists of the micro scanner, a light source and photodetector with a pinhole and features a higher resolution detection compared to the conventional method such as trigonometrical measurement using a Position Sensitive Detector (PSD). The sensor is capable of high resolution detection in the range 40 mm to 50 mm with an accuracy of less than 1 mm when the size of the sensor is 2 mm/spl times/4 mm. This sensor could be applied to the sensor for a micro maintenance robot.

Two-dimensional silicon micromachined optical scanner integrated with a photodetector

A highly miniaturized optical scanner integrated with a photo detector has been developed for miniaturization of scanning type of optical sensors. The scanner is fabricated by silicon micromachining technologies and is driven by a piezoelectric actuator. It is capable of two dimensional scanning and photo detection. The scanning angle is over 40 deg X 30 deg and the photo detecting sensitivity is 0.49 A/W for 680 nm wavelength light.

Basic Characteristics Of A Piezoelectric Buckling Type Of Actuator

An actuator which utilizes buckling motion due to piezoelectric transverse stress is present. It will be a key part of Micro Focusing Device(MFD) which changes focal length of light from a light source. Sputtered PZT(Pb(Zr/sub x/ Ti/sub 1-x/)O3:x=0.54) was used as piezoelectric material and piezoelectric coefficient(d/sub 31/) of 45 pC/N was obtained. It was confirmed that the actuator can produce enough deflection for MFD application by non-linear elastic theory calculation with thin film mechanical characteristics and d/sub 31/ data.