Comb-drive

R. R. A. Syms, B. M. Hardcastle, and R. A. Lawes, Bulk micromachined silicon comb-drive electrostatic actuators with diode isolation, Sensors Actuators A 63, 61, 1997. 

First, a bias voltage applied between the fixed comb drive electrodes and the movable comb drive electrodes connected to a seismic mass suspended by a... 

For the following example, the function is not directly obvious from Fig. 7.2.1. A flat disc-shaped rotor, suspended by flexible beams at a central point, is set into horizontal, rotational vibrations by comb drive structures. If a turning movement occurs in the plane of the sensor chip, the rotor responds with a perpendicular tilt due to the conservation of angular momentum by Coriolis forces. The distance of the rotor disc to the substrate is detected capacitively and provides a signal proportional to the yaw rate. As the rotary oscillation periodically changes its direction, the whole structure executes tilt oscillations towards the substrate with the frequency of the drive (Fig. 7.2.14, Fig. 7.2.15). 

The comb drive microresonator used for this study is shown in top and side view in Fig. 1. The main components of the resonator are a shuttle structure comprised of the connected back-to-back combs, two suspended folder beams with one end anchored to the substrate, and fixed comb drives. Table 1 lists some key dimensions of the resonator. 

Motion is generated by electrostatic attraction force between electrically charged surfaces. Examples of electrostatic MEMS actuators are in-plane comb drives (Fig. la) and out-of-plane parallel plate actuators (Fig. lb) [4]. Both types of actuators require large driving voltages... 

Microactuators, Fig. 1 Diagrams of (a) in-plane electrostatic comb-drive actuator and actuation force and (b) out-ofplane parallel plate electrostatic actuator... 

Silicon Micromachining, Fig. 7 Schematic plan view of a MEMS device with comb-drive structure... 

The surface micromachining technique is a CMOS-compatible process and has some advantages over the bulk micromachining one. The most popular microstructure is the so-called comb-drive structures as shown in Fig. 7. Several commercially available sensors with integrated circuit on chip have been developed by using this technique such as accelerometers, gyroscopes, microphones, etc. 

Silicon Micromachining, Fig. 8 Illustration of the comb-drive stmcture in SOI (silicon-on-insulator) wafer fabricated using surface micromachinmg... 

A new type of structure was invented to overcome the limited deflection capability of the parallel plate capacitor the so-called comb drive [302]. An example of this is shown in Fig. 6.111. This structure can easily be im-... 

Dao Comb-drive 134 fingers of 0.2 450x250x30/zm 15pm, 20Hz High, high... 

Since the output force of the comb drive is the same in both cases, we may express equations 3 and 4 in terms of Fc, equate, and solve for fa, yielding... 

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