Electrostatically Controlled Linear Inchworm Actuator for Precise Step and Parallel Motion

Abstract

This paper describes electrostatically controlled linear inchworm actuator (hereafter ECLIA). Besides accuracy, large stroke motion and high throughput become important to improve positioning efficiency. ECLIA can drive its sliders in parallel with high accuracy and large stroke. ECLIA works based on the inchworm motion controlled by the electrostatic clutch mechanism. The electrostatic clutch mechanism can control a transmission of motion from an oscillator to sliders. ECLIA can provide precise motion due to a piezoactuation of the oscillator and large stroke through an electrostatically controlled inchworm motion. ECLIA is developed by MEMS technology in this study. MEMS technology provides multi sliders in batch by taking an advantage of IC fabrication process. The electrostatic clutch method makes it possible to control parallel motions of multi sliders. Fig. 1 shows a schematic drawing of a typical ECLIA. Seven sliders are shown in Fig. 1. Suppose that multi sliders move independently with the aim of accomplishing their desired tracking motions.The system consists of a driving system and a slider system as shown in Fig. 1. The driving system is composed of a piezoactuator and an electrostatic clutch system. The electrostatic clutch system of the driving system has two electrodes: 1) Holding-electrode fixed on the substrate; 2) Movable driving-electrode. Fig. 2 explains motion principle of the system. A case for a forward motion of a slider is represented here. A chart of control signals corresponding to forward, backward, still or stop motion is shown in Fig. 3. The electrostatic clutch motion is synchronized with the piezoactuation through a combination of two electrodes so as to accumulate the piezoactuation step by step. Sliders are insulated each other controlled independently depending on tis electrical potential. Each sliders travels Fig. 1. Schematic drawing of a typical ECLIA forward, backward, and stops by control signals. MEMS technology is used to fabricate ECLIA. DRIE of Si following anodic bonding can provide islanded Si sliders. Parylene C coating on the surface of Si sliders guarantees insulation of adjacent sliders. In the last step, Au film is deposited on the tip of sliders to form mirror surfaces. Fabrication results of isolated sliders are shown in Fig. 3. 16 sliders bonded on a glass substrate are shown in Fig. 3. A slider is 9 mm long and 600 µm wide. 200 nm step was achieved when 50 V was applied to the piezoelectric oscillator. Isolated sliders could move independently as desinged.Optical application of ECLIA is ongoing toward high resolution dynamic gain equalizer as WDM spectral attenuator. Fig. 2. Motion Principle (Cross-section) Fig. 3. Developed ECLIA with 16 sliders -9 -This paper presents electrostatically controlled linear inchworm actuator for precise step and parallel motion. Electrostatically controlled linear inchworm actuator can provide a high accuracy (nm order), a large stroke (mm order) and parallel motion of multi sliders. Micro electro mechanical systems technology ...

Picoliter Controllable Syringes Driven by Parallel Motions of Electrostatic Controlled Linear Inchworm Actuator

“…Our group has been studying an electrostatic actuator, ECLIA, for several years focusing on its outstanding features of the slider motion: parallel and precise motions with large stroke, which are obtained by the combination of piezoactuation and the inchworm motion [12][13][14][15]. Up to date, the actuator has been applied to optical Dynamic Gain Equalizer (DGEQ), so that parallel motions and large strokes of sliders can perform as distributed optical attenuators for Wavelength Division Multiple (WDM) signals [14,15].…”