Fully integrated automatic microfluidic setup for immobilization, analysis and non-selective release of particles

We present a microfluidic device that enables trapping, analysis and on-demand release of individual microparticles using membrane deformation induced by pneumatic actuation. Inspired by the Pachinko -like architecture, the system integrates an array of traps supported by a deformable membrane. The latter is actuated by pressure control in a pneumatic chamber bonded above it. Unlike conventional designs with rigid guiding structures, our modified configuration maximizes trapping membrane mobility by introducing a wide, elliptical cavity and suspended rectilinear flow guides. To characterize the device, we performed deformation measurements under controlled negative pressure using confocal microscopy. These measurements revealed pressure-dependent displacement profiles, which were compared to several theoretical models. A strong agreement was observed with the thick-membrane approximation, confirming its suitability for future scaling. Deformation in the z-direction reached over 120 μm under −100 mbar in the pneumatic chamber, enabling the release of 80-μm-diameter particles. Trapping and release sequences were demonstrated under a microscope by applying controlled fluidic and pneumatic pressures. The device reproducibly captured and released microparticles within seconds. To highlight the automation potential, we integrated a custom Python-based interface using μManager libraries to control imaging, motion, and fluidic systems (accessible in this paper to be used by the readers). The platform autonomously performed full cycles of particle trapping, image acquisition, and release, including priming steps to prevent air bubble formation in the PDMS microchannels. This work demonstrates a robust and fully automated microfluidic platform capable of reversible particle immobilization. The system is suitable for applications requiring high-throughput single-object analysis, such as screening assays, mechanobiology, or dynamic imaging workflows. • Automated microfluidic system enables precise trapping, analysis and release of microparticles. • Microfabrication of a trapping microfluidic chip that include releasing phase thanks to pneumatic actuation. • Confocal measurements validate thick-membrane model for deformation prediction. • μManager-controlled platform performs trapping, imaging, and release autonomously.