A high performance MEMS platform for actuation and sensing

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We have recently developed in our research group an ultra-thin (0.5 mm) novel 3-degrees-of-freedom micro-electrostatic actuator platform and shown through initial implementation examples its potential as a platform that can address long standing problems of micro electrostatic actuators as well as its use as a high performance micro accelerometer and force micro sensor. The micro actuator platform was fabricated and tested to demonstrate large force generation and manipulation of up to 100 milligram size masses and a stroke of 100 µm. Further development of the technology is needed for its implementation for autofocus (AF) and optical image stabilization (OIS) in smart phone cameras. The camera modules to be developed use the novel actuator to achieve AF based on translation along the optical axis and 2 axis rotation along axes forming the plane perpendicular to the optical axis of the image sensor. Achieving AF using image sensor actuation provides almost instant focus in which the camera switches the focus form one scene to another in a very short time. Another advantage is the high resolution (±1µm) of the actuator as opposed to ±10 µm resolution of the currently widely used electromagnetic Voice Coil motor technology (VCM). This high resolution enables the use of large aperture cameras which allow more light to enter the image sensor. The OIS feature will be pursued by acting on the lens barrel by using a second micro actuator. ***The camera is widely used in mobile phones and a significant battery drain is observed when used. The micro-actuator platform is expected to significantly reduce the power consumption by using electrostatic actuation technology as opposed to electromagnetic VCMs currently in use. The peak power requirement for our actuator is of the order of 1 mWatt as opposed to 100-200 mWatt for typical VCMs. The implementation of the technology in handheld devices such as smart phones requires that the operating voltages for the MEMS actuators are limited to 37V. Further development of the technology is needed to enable image sensor signal routing within the micro-chip and lower the required voltage from 80V to a maximum of 37V. Further development is also needed to achieve simultaneously autofocus and optical image stabilization by enabling 3 degrees of freedom motion of each the image sensor and lens barrel of the camera. The micro-electrostatic platform will also be implemented to develop 3D touch screens in smart phones by using it as an ultra sensitive force and position sensor based on a single transparent layer. It is also to be implemented as multi-axis accelerometers that are characterized by large range, wide bandwidth, ultra low noise floor and very high sensitivity due to the design itself and is shown to be uniquely suitable for a number of applications requiring very high sensitivity.