Central to advancing our understanding of neural circuits is developing minimally invasive, multi-modal interfaces capable of simultaneously recording and modulating neural activity. Recent devices have focused on matching the mechanical compliance of tissue to reduce inflammatory responses. However, reductions in the size of multi-modal interfaces are needed to further improve biocompatibility and long-term recording capabilities. Here a multi-modal coaxial microprobe design with a minimally invasive footprint (8–14 µm diameter over millimeter lengths) that enables efficient electrical and optical interrogation of neural networks is presented. In the brain, the probes allowed robust electrical measurement and optogenetic stimulation. Scalable fabrication strategies can be used with various electrical and optical materials, making the probes highly customizable to experimental requirements, including length, diameter, and mechanical properties. Given their negligible inflammatory response, these probes promise to enable a new generation of readily tunable multi-modal devices for long-term, minimally invasive interfacing with neural circuits.
This paper presents modeling, designs, and initial experimental results demonstrating successful untethered microscale flight of stress-engineered microscale structures propelled by thermal forces. These MEMS Microfliers are 300 μm×300 μm×1.5 μm in size and are fabricated out of polycrystalline silicon using a surface micromachining process. A concave chassis, created using a novel in-situ masked post-release stress-engineering process, promotes static in-flight stability. High-speed optical micrography was used to capture image sequences of their flight, and this imagery was subsequently used to analyze their mid-flight performance. Our analysis, combined with finite element modeling (FEM) confirms stable flight of the microfliers within the thermal gradient above the heaters. This novel microscale flying platform presented in this paper may pave the way for new types of aerial microrobots.
This paper describes initial work on untethered microscale flying structures as a platform for new class of aerial MEMS microrobots. We present and analyze both biomimetic structures based partially on wing designs of smallest flying insects on Earth, as well as stress-engineered structures powered by radiometric (thermal) forces. The latter devices, also called MEMS Microfliers are 300 μm × 300 μm × 1.5 μm in size, and are fabricated out of polycrystalline silicon. A convex chassis, formed through a novel in-situ masked post-release stress-engineering process, ensures their static inflight stability. High-speed optical micrography was used to image these MEMS microfliers in mid-flight, analyzing their flight profile.
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