To ensure a safe working environment, non-dispersive mid-IR gas-sensing system is often used in the measurement of the concentrations of hazardous or combustible gases. The essential component of a NDIR gas-sensing system includes a mid-IR radiation source, a waveguide, and an IR detector. MEMS will be the core technology to realize such a handheld system.
Selected Publications:
In the optical MEMS regime, microstructures including mirrors, lenses and gratings are driven to move or deform by actuators so that unique functions such as beam steering can be achieved. In recent years, MEMS scanners have created growing interest, fuelled in part by the emergence of handheld pico projectors, which have intriguing applications in consumable electronics, IT and the amusement industries.
In our first research attempt on MEMS scanners, we have demonstrated a silicon micromirror driven by 1x10 piezoelectric Pb(Zr,Ti)O3 beam actuators. The ten PZT actuators are electrically connected in series and 2-D scanning patterns can be obtained by biasing actuators 1-5 and 6-10 at a resonant frequency corresponding to bending and torsional modes respectively. In our subsequent effort, we separated the electrical connections to the ten piezoelectric actuators so as to allow for individual biasing of the actuators. Similar to the first design, this mew design can operate in three modes: bending, torsional and mixed. A 2-D raster scanning pattern was achieved in mixed mode when the bending and torsional modes are superimposed together. To further increase the rotation angle and reduce the driving voltage of our previous design, development work on another piezoelectric driven 2-D MEMS scanner using a single meandering S-shaped PZT actuator is explored.
A novel CMOS compatible 2-D MEMS scanner based on hybrid actuation mechanisms is proposed. Both electrothermal and electromagnetic actuations have been integrated in the same device for slow and fast scanning purposes respectively. This is different from prior MEMS scanner designs where the two orthogonal scanning axes are driven by the same actuation method. Furthermore, its CMOS compatible fabrication process allows for easy monolithic integration of integrated electronics to control the actuation. The low operating voltage makes the proposed MEMS scanner potentially suitable for mobile pico projector applications powered by batteries with limited capacity.
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