TR&D1

University Of Michigan At Ann Arbor, Ann Arbor MI

Investigators

Abstract

KR Oldham and X Liang will serve as Project Lead and co-Lead, respectively, for TRD1. They will perform design, fabrication, and verification of microsystems scan mirrors based on parametric resonance, thin-film PZT, and electrothermal mechanisms, and will develop 2D material enhanced transducers that will permit individual transducer size reduction while maintaining high sensitivity in arrays with small element spacing to optimize axial resolution. Parametric resonance devices will be developed to achieve fast scan speeds with hysteresis free behavior using low power consumption in a small footprint. A reflector will be supported by a gimble, and driven by comb drive actuators to provide wide angular deflections. The gimble will be mounted on suspensions that act as levers to generate out-of-plane motion to produce large axial displacements for increased imaging depths. Our design architecture combines softening dynamics of electrostatic transduction with stiffening dynamics of the lever structure to substantially extend range of motion relative to conventional electrostatic scanners. We will refine suspension and comb finger geometries to maximize the scan frequencies in progressively smaller form factors. Thin-film PZT materials have exceptional work density, and will be developed to generate large forces at low operating voltages. Piezoelectric benders will be used to achieve extremely large displacements in static or dynamic (resonant) operation. Serpentine leg geometries will be utilized to support large translational or rotational displacements. Piezoelectric actuators will be developed to achieve accurate positioning on the submicron scale with no backlash. TRD1 will demonstrate random access scans whereby arbitrary position control can be performed by independent actuation of individual legs in user-defined directions in 2- or 3-axes with integrated feedback control for position regulation. 2D materials will be developed for transduction provide exceptional material properties, in mechanical, electrical, and optical domains, that cannot be replicated with conventional thin-films. TRD1 will apply expertise in material growth, patterning, and transfer to enhance performance of PMUT arrays, by structuring individual transducers to maximize strain in piezoelectric active layers while 2D material properties enable close array placement. Electromechanical models will be developed to account for nonlinearities encountered in dynamic microsystem operation, including geometric and material stiffening effects, electrostatic softening, damping variation, and material hysteresis. These models permit rapid adaptation to new instrument requirements including those of multiple CPs. Synergy: TRD1 enables miniaturization of novel microendoscopes in TRD2 through integration of microsystems scanners and transducers. TRD2 validates scanner performance in imaging experiments. TRD1 provides scan patterns that allow TRD3 to generate panorama and 3D image reconstructions. TRD3 provides fluorescence denoising and motion mitigation algorithms to increase TRD1 scan speeds and direct user-defined ROIs during real-time in vivo imaging.