A preliminary study on the dynamic characterization of a MEMS microgripper for biomedical applications

First results on the functional characterization of two rotary comb-drive actuated MEMS microgripper with different geometry

“…The comb-drive angular displacement and the gripper tip displacement have been evaluated through a measurement procedure that performs a tracking of virtual markers inserted frame by frame within predetermined Regions Of Interest (ROIs) as shown in Fig. 4 [15][16][17][18]. As regards the comb-drive videos, the Instantaneous Center of Rotation (ICR) of the comb-drive has been obtained on the first frame from the intersection of two lines drawn by the operator, and the angular displacement has been evaluated as follows:…”

“…UNCERTAINTY ANALYSIS In order to discuss the obtained results, an uncertainty analysis considering the main sources of uncertainty has been carried out. In according with the approach adopted in [13][14][15], Type A and Type B uncertainties have been combined [19], following: Type A uncertainties σA have been evaluated considering the standard deviation of the obtained results, while Type B uncertainties σB have been calculated by taking into consideration the following sources of uncertainty present in the measurement chain, listed in Table 3: x Arbitrary/Function Generator on signal amplitude and frequency, reported in the datasheet. x Power amplifier uncertainty on amplitude, reported in the datasheet.…”

“…The MG prototypes under examination are equipped with electrostatic rotary comb-drives and Conjugate Surface Flexure Hinges (CSFHs) and fabricated monolithically on a Silicon-on-Insulator (SOI) wafer with an aluminum hard mask, through a process of Deep Reactive Ion Etching (DRIE) [9][10]. Previous studies available in literature [11][12] have presented a theoretical formulation describing the electrostatic torque exerted by rotary comb-drives, which is a function of the geometric characteristics of the micro-actuator, whose nominal values have been reported in Table 1, and the square of the supply voltage and have evaluated the displacement as a function of the latter [13][14][15]. This preliminary study, based on image analysis method, aims to investigate the design of MG prototypes by analyzing the relationship between gripper tips displacement and the number of active micro-actuators, as a function of supply voltage and to verify if doubling the electrostatic torque applied by the comb-drives, the prototype displacements double, as assumed by the theoretical model [9][10][11][12].…”

Image quality comparison of two different experimental setups for MEMS actuators functional evaluation: a preliminary study

“…Microgrippers (MGs) are devices based on MEMS (Micro Electro-Mechanical System) technology, able to grasp and manipulate objects of microscopic size, suitable for a wide range of applications, especially in the biomedical field and in particular, the manipulation of cells and tissues where they can contribute to the development of minimally invasive surgery techniques and the characterization of biological samples [1][2][3]. In this regard, the present study is part of a research aimed at developing image analysis-based measurement methods and systems for the characterization of electrostatic actuated MGs [4][5][6][7][8][9]. The Device Under Test (DUT) is the MG prototype in Fig.…”

“…1, fabricated by Deep Reactive Ion Etching (DRIE) process, using an aluminum hard mask on a silicon-oninsulator wafer [4][5]. Previous studies from the Authors [5][6][7][8] focused on measuring the displacement as a function of the supply voltage. Due to the small displacement values obtained for low supply voltage values and the small size of some parts of the device (e.g., the fingers thickness in the comb-drives is 4 μm only), the optical setup should be able to acquire images whose quality guarantee the measurement of a few microns and therefore the performance of a digital imaging system for this type of analysis in optical microscopy strongly depends also on the camera used for image digitalization.…”