Early examples of computers were almost exclusively based on mechanical devices. Although electronic computers became dominant in the past 60 years, recent advancements in three-dimensional micro-additive manufacturing technology provide new fabrication techniques for complex microstructures which have rekindled research interest in mechanical computations. Here we propose a new digital mechanical computation approach based on additively-manufacturable micro-mechanical logic gates. The proposed mechanical logic gates (i.e., NOT, AND, OR, NAND, and NOR gates) utilize multi-stable micro-flexures that buckle to perform Boolean computations based purely on mechanical forces and displacements with no electronic components. A key benefit of the proposed approach is that such systems can be additively fabricated as embedded parts of microarchitected metamaterials that are capable of interacting mechanically with their surrounding environment while processing and storing digital data internally without requiring electric power.

No abstract

This paper reports real-time explosive gas sensing (DNT) in atmospheric pressure utilizing the noise squeezing effect that occurs before a bifurcation event. A noise-squeezing controller based on the statistics of phase noise is implemented using high-speed LabVIEW field programmable gated array. A high frequency TNT-molecularly imprinted fixed-fixed microbeam sensor utilizes this nontraditional sensing strategy and performs DNT sensing at various concentrations. Experiments are conducted using both noise-based and sweep-based bifurcation tracking for a direct comparison. Results demonstrate noisebased bifurcation tracking is not only capable of performing reliable frequency tracking, but also show the method is superior to the bifurcation sweep-based tracking. Over three orders of magnitude improvement in acquisition rate is achieved, and as a result, confidence and precision on bifurcation frequency estimation is significantly improved over the bifurcation sweep tracking method, enabling DNT sensing at concentrations much below sub-ppb (parts-per-billion) level.[2013-0339]

Designing mechanical metamaterials is overwhelming for most computational approaches because of the staggering number and complexity of flexible elements that constitute their architecture—particularly if these elements don’t repeat in periodic patterns or collectively occupy irregular bulk shapes. We introduce an approach, inspired by the freedom and constraint topologies (FACT) methodology, that leverages simplified assumptions to enable the design of such materials with ~6 orders of magnitude greater computational efficiency than other approaches (e.g., topology optimization). Metamaterials designed using this approach are called directionally compliant metamaterials (DCMs) because they manifest prescribed compliant directions while possessing high stiffness in all other directions. Since their compliant directions are governed by both macroscale shape and microscale architecture, DCMs can be engineered with the necessary design freedom to facilitate arbitrary form and unprecedented anisotropy. Thus, DCMs show promise as irregularly shaped flexure bearings, compliant prosthetics, morphing structures, and soft robots.