Fluid cells flanked by thin membranes transparent to electron or X-ray beams have been developed in the past for microscopy and spectral analyses of liquid/gaseous samples, interfaces, and atomic/molecular- scale reactions, to support 1 bar pressure differences, as suited for work in regular vacuum chambers. Many technological and environmentally-important phenomena (e.g. high-pressure underground mineralization, catalysis and reactions at high pressure, etc.), would require greatly improved leak- free/vacuum-safe new MHPFCs to allow multi-reactant/electrode studies of the same type, at pressures of hundreds of bar. The subject of this Phase I SBIR is the development of such cells. Membranes can be made to resist pressure by reducing their size and increasing their thickness, but for 300+ bar and a reasonable effective analysis area, with constraint in thickness to tens to hundreds of nm due to transmission requirements, one needs to cleverly solve the compromise between thickness and area, bringing into play thickness distributions and corner reinforcements within a computer-based optimization. The approach will seek to eliminate stress concentrations at the membrane edges by precisely adjusting the membrane thickness, shape, residual stress, and composition. Optimized membranes will be integrated into fully-functional MHPFCs by bonding two identical Si parts, including each 4 feed-through channels, electrical leads/connection pads, and a pressure sensor, then assembled the bonded Si parts with ISO-guidelines-compliant fluid and electrical connectors. Various specific mounts for X-ray and electron beam requirements will be developed. During Phase I, membrane optimization will be accomplished in collaboration with Northwestern University, who has expertise in membrane deflection, size effects for ultra-thin structures, stress engineering and simulations. Alcorix will manufacture and validate the membranes in-house with a high- pressure bulging setup, while also fabricating working/testable chips with simple membranes and no pressure sensor. During Phase II, a family of range- and purpose-customized devices with engineered membranes and integrated pressure sensors will be fabricated and tested, leading to a family of products. Potential customers for MHPFCs include: beam line scientists, electron microscopists, scientists from high-energy laser facilities, and many diverse labs â a community which Alcorix currently serves. While simple fluid cells withstanding only 1 bar and no microfluidics/electrodes can be low cost, (~$59/pc), the targeted cells are high-value, due to their exquisite features (>300 bar, multifluidic ports, multielectrode, integrated pressure sensor, plug-in ready). The estimated global market is ~$2.5M today and up to $8.1M in 10 years, out of which Alcorix can capture 100% as unique producer or 75% as producer and licensee