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An affordable 3D-printed positioner fixture improves the resolution of conventional milling for easy prototyping of acrylic microfluidic devices.

We present a simple and low-cost positioner fixture to improve the fabrication resolution of acrylic microchannels using conventional milling machines. The positioner fixture is a mechatronic platform that consists of three piezoelectric actuators assembled in a housing made of 3D printer parts. The upper part of the housing is raised by the simultaneous actuation of the piezoelectric elements and by the deformation of 3D-printed hinge-shaped supports. The vertical positioning (Z-axis) can be controlled with a resolution of 500 nm and an accuracy of ±1.5 μm; in contrast, conventional milling machines can achieve resolutions of 10 to 35 μm. Through simulations, we found that 3D-printed hinges can deform to reach heights up to 27 μm without suffering any mechanical or structural damage. To demonstrate the capabilities of our fixture, we fabricated microfluidic devices with three weir filters that selectively capture microbeads of 3, 6 and 10 μm. We used a similar weir filter design to implement a bead-based immunoassay. Our positioner fixture increases the resolution of conventional milling machines, thus enabling the fast and easy fabrication of thermoplastic fluidic devices that require finer microstructures in their design.