360° rotating micro mirror for transmitting and sensing optical coherence tomography signals

We have designed a micro actuator system for precise transmission and reception of bio-optical signals. Our system consists of a first-in-kind polysilicon micro mirror held stationary at a 45° angle on top of a 360°-rotating platform driven by a scratch drive array. The entire system is designed with a 1-mm diameter size constraint. This constraint allows the device to fit inside the tip of a catheter for use in biomedical endoscopy. We have developed two designs, based on a commercial micromachining process, to accomplish this. One mirror assembly is pulled into position at 45° while the other mirror assembly flips over itself into place. The benefit of the former mirror is that it can easily be coated with gold to improve reflectivity at the foundry. The benefit of the latter is that the optically-flat bottom surface of the polysilicon layer is used as the reflective surface of the mirror. Photoresist "hinges" are used to allow this system to self-assemble by surface tension induced through heating.