Micro-acousto-electro-mechanical systems (MAEMS). A systemic approach for a pervasive ultrasound

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Ultrasound (US) imaging systems provide significant advantages that justify why they remain the dominant clinical imaging procedure (more than 25%), and the use of ultrasound outside the medical field, in non-destructive testing (NDT), industrial (e.g. automotive)  or consumer applications (e.g. for haptic interfaces). We have developed a novel, low-cost, polymer based microfabrication technology for Capacitive Micromachined Ultrasonic Transducer (CMUT) arrays, with a fabrication cycle of days, and competitive transducer performance. The present research program propagates the benefits of this technology, in a structured way, to the various architectural layers of an ultrasound system, to address most of the present challenges in US imaging and align with a vision where ultrasound will become ubiquitous. We entitle the program "from MEMS to MAEMS", to emphasize on the expansion of already pervasive MEMS (Micro-electro-mechanical systems) into a wider MAEMS (Micro-acousto-electro-mechanical systems) realm. Several major challenges in US systems are addressed in a combined  and novel manners, at different coupled levels: technology development, device innovations, electronic interface, hybrid integration and assembly, array signal processing and intelligent data fusion. Low-cost, even disposable US transducers and systems are achievable through low-cost and green transducers microfabrication, combined with mostly digital electronic interfaces and hybrid assembly solutions (3D printing). Individual-level customization, impossible in classic Si-foundries manufacturing, is possible through the rapid microfabrication cycle (1-2 days), combined with programmable digital electronics and a fast and concurrent design and simulation cycle using extracted reduced-order macromodels (ROMs). High performance imaging will be obtained through large area US arrays on flexible substrates (conformal US), enabling 3D imaging, multi-imaging fusion (e.g. X-Ray + US or opto-acoustic) that relies on the optical and X-Ray transparency of the polymer used, and adaptive beamforming based on data fusion,  using information from extra curvature/position sensors embedded in the array.  The interconnection/communication bottleneck for  a large number of channels are addressed through stacked assemblies of polyCMUT arrays and electronics, digital bitstreams channels, combined with compressive sensing. Advanced signal processing applications will combine super-resolution imaging algorithms with the electrical programmability of polyCMUT (through variable DC bias voltages). The integrated path in designing US systems presents unique opportunities for optimizations and novelties through coupling between different system layers. Two main applications are targeted, to validate the power of our approach: a low-cost conformal US system for biomedical imaging (heart monitoring) and a large area imaging system for NDT of CFRP plates used in the aerospace industry.