Recent advances in multiscale manufacturing enable fabrication of hollow-truss based lattices with dimensional control spanning seven orders of magnitude in length scale (from ;50 nm to ;10 cm), thus enabling the exploitation of nano-scale strengthening mechanisms in a macroscale cellular material. This article develops mechanical models for the compressive strength of hollow microlattices and validates them with a selection of experimental measurements on nickel microlattices over a wide relative density range (0.01-10%). The limitations of beam-theory-based analytical approaches for ultralight designs are emphasized, and suitable numerical (finite elements) models are presented. Subsequently, a novel computational platform is utilized to efficiently scan the entire design space and produce maps for optimally strong designs. The results indicate that a strong compressive response can be obtained by stubby lattice designs at relatively high densities (;10%) or by selectively thickening the nodes at ultra-low densities.

Recent advances in multi-scale manufacturing enable fabrication of hollow-truss based lattices with dimensional control spanning seven orders of magnitude in length scale (from ~50nm to ~10cm), offering tremendous potential for multifunctionality. Topology optimization is essential to realize the full potential of these micro-architected materials. This paper presents a novel optimal design and modeling platform, consisting of four interconnected tools: (i) a geometric modeling algorithm; (ii) a meshing algorithm; (iii) an optimal design code; and (iv) a communication interface with a commercial Finite Elements program (Abaqus). The powerfulness of the proposed platform is demonstrated for the optimization of specific stiffness in pyramidal hollow micro-lattices. R Figure 1. Schematic of a Micro-Architected Material based on a Hollow-Truss Pyramidal Lattice (from [1]).

This paper presents the design, optimization and manufacturing of a novel micro-fabricated load cell based on a double-ended tuning fork. The device geometry and operating voltages are optimized for maximum force resolution and range, subject to a number of manufacturing and electromechanical constraints. All optimizations are enabled by analytical modeling (verified by selected finite elements analyses) coupled with an efficient C++ code based on the particle swarm optimization algorithm. This assessment indicates that force resolutions of ∼0.5-10 nN are feasible in vacuum (∼1-50 mTorr), with force ranges as large as 1 N. Importantly, the optimal design for vacuum operation is independent of the desired range, ensuring versatility. Experimental verifications on a sub-optimal device fabricated using silicon-on-glass technology demonstrate a resolution of ∼23 nN at a vacuum level of ∼50 mTorr. The device demonstrated in this article will be integrated in a hybrid micro-mechanical test frame for unprecedented combinations of force resolution and range, displacement resolution and range, optical (or SEM) access to the sample, versatility and cost.

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