Characteristics of MEMS scanners with different driving bias Parima Tantipiriyakij 2 , Porntipa Sankatumvong 2 , Pongsak Sarapukdee 1 , Santi Rattanavarin 2 , Ungkarn Jarujareet 2 , Numfon Khemthongcharoen 2 , Athisake Ruangphacha 1 , Il Woong Jung 3 and Wibool Piyawattanametha 1,2 1 Advanced Imaging Research Center, Faculty of Medicine, Chulalongkorn University, Bangkok, Thailand 2 National Electronics and Computer Center, Pathumthani, Thailand 3 Center for Nanoscale Materials, Argonne National Laboratory, Argonne, Illinois, USA Abstract—In this paper, two different designs of two-dimensional MEMs scanner were tested to find their characteristic responses in dynamic mode by applying a fixed voltage at different electrical biasing waveforms: sinusoidal, triangle, square and saw-tooth waveforms. The collected data from the experiment has proven that the significance of MEMS scanner design and driving input signals. Keywords-2-D MEMs scanner; cervical cancer; confocal microscope; frequency responses; mechanical angle I. INTRODUCTION Cervical cancer is one of the most common causes of cancer related death in women [1]. For early diagnosis of the disease, a non-invasive early detection technique for cervical cancer has been developed by using a handheld multispectral confocal microscope employing a two-dimensional (2-D) MEMS scanner as a key scanning element to raster laser beam [2,3,4]. The purpose of this work is to investigate the driving waveforms used to actuate MEMS scanners and determine suitable driving waveforms to raster scan the laser beam to obtain confocal imaging. Therefore, various types of actuation voltages are being explored compared with the conventional driving waveform used to bias MEMS scanners. II. EXPERIMENTAL PROCEDURE The experiments were conducted by using two different designs of MEMS scanners called Device 1 and Device 2. MEMS scanner are designed by Argonne National Laboratory and fabricated at Silex Microsystems. MEMS scanners were made up of a single SOI layer having the dimension of 3.25mm x 3.25mm, with the thickness of 10 micrometers. The scanner is designed for achieving biaxial degree of freedom and is actuated by electrostatic driving force [2]. Device 1 possesses asymmetric torsional mirror design while device 2 has symmetric torsional mirror design as shown in Fig. 2a and 2b, respectively. The setup instruments for this experiment are a CW laser source (JDSU, helium neon gas laser), a position sensing detector (PSD) and a MEMS holder. The read out from the PSD is connected to a personal computer. Fig. 1 illustrates a schematic drawing of the experiment setup. The driving waveforms generated by a function generator (Agilent Technologies, DSO 1004A 60 MHz) are sinusoidal, triangle, square, and saw-tooth waveforms. In order to obtain a resonant peak from dynamic characteristic of a MEMS scanner, unipolar driving bias of 40V was used throughout the study. Peak frequencies from V1 (outer), V2 (outer) and V3 (inner) axes were determined. The rotational angle conversion for each driving voltage is accomplished by using the function below [5] : Figure 1. Instrumental setup[2]         Figure 2. Type of MEMS scanner devices. (2a) Device 1 (2b) Device 2. III. RESULT & DISCUSSION Figure 3. Output response of V2 in Device 2 collected by the PSD, from 0 to 900 Hz. V1 and V2, actuate outer axis and it is represented as X-axis while V3 actuate inner axis and it is represented as Y-axis. 0 0.2 0.4 0.6 0.8 1 0 100 200 400 500 600 700 800 900 Response Voltage (V) Frequency (Hz) Output Response X-MAX Y-MAX GND GND D V2 D V2 V3 2 GND V1 D V1 1 GND GND GND D V2 2 V V3 3 V1 GND GND D V2 2 GND D V1 GND 2a 2b 978-1-4673-5696-1/12/$26.00 ©2012 IEEE