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Retinal prostheses implemented by means of electrical stimulation of retinal ganglion cells have been previously demonstrated with 16 and 60 channel microstimulator arrays. Blind patients with severe retinal degeneration (e.g., retinitis pigmentosa (RP) have been able to use these devices to navigate and read large letters. However, to dramatically improve the effectiveness of such prostheses, and to enable a variety of neural stimulation implants, channel densities of 1000 per cm 2 and higher are highly desirable. This paper reports on a novel approach to an integrated bioelectronic package with high density electrical feedthroughs, capable of 1024 stimulator channels in a 5 mm × 5 mm area using liquid crystal polymer (LCP) substrates to enable implantable retinal prostheses.A novel fusion bonding process was demonstrated to achieve fine pitch interconnections with high adhesion strength and biocompatible metal-polymer interfaces. Helium leak rates of 1 × 10 -9 mbar-l/sec were measured for LCP samples without feedthroughs, representative of penetration through the bulk LCP film, and leak rates of < 5 × 10 -8 mbar-l/sec were measured for feedthrough array samples, comparable to leak rates demonstrated for glass substrates with metallized vias.

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Micro total analysis systems (μTAS) are highly attractive across numerous fields including science, engineering, and medicine due to their portability, low power use, and efficient sample and reagent consumption. Development of fully functional microfluidic devices is based on iterative design and testing of multiple prototype microdevices, and the use of hazardous conventional microfabrication methods makes this iterative process resource-intensive and prohibitive for many users worldwide. Rapid prototyping techniques can alleviate these issues, enabling accelerated development of microfluidic structures at reduced costs, making this technology available to a broader user base, from classrooms to researchers in laboratories with limited resources. Here, we present a green, low-cost, user-friendly elastomeric (GLUE) rapid prototyping method to fabricate custom master molds for polydimethyl­siloxane (PDMS)-based microfluidic devices, using an application of water-soluble poly­(vinyl acetate) (PVAc) glue. The smallest features of the molds are on the order of 80 μm wide, with tunable height control from 10 to 60 μm. This method is capable of fabricating three-dimensional features. As a proof of concept, several microfluidic devices ranging from a droplet generator to a lifting gate pneumatic microfluidic processor were fabricated to demonstrate the versatility and applicability of our method. To the best of our knowledge, this is the first rapid prototyping process that can be used either as a print-and-peel method or as a scaffolding technique using the same process and patterning material. The simplicity and inexpensive nature of this application of PVAc glue can significantly improve the development of integrated μTAS devices, while also making microfluidics greener and accessible to researchers with limited resources and little to no experience in the field.