Fabrication of Free-Standing, Self-Aligned, High-Aspect-Ratio\nSynthetic Ommatidia

Abstract

Free-standing, self-aligned, high-aspect-ratio\n(length to cross-section, up to 15.5) waveguides that mimic insects’\nommatidia are fabricated. Self-aligned waveguides under the lenses\nare created after exposing photoresist SU-8 film through the negative\npolydimethylsiloxane (PDMS) lens array. Instead of drying from the\ndeveloper, the waveguides are coated with poly­(vinyl alcohol) and\nthen immersed into a mixture of PDMS precursor and diethyl ether.\nThe slow drying of diethyl ether, followed by curing and peeling off\nPDMS, allows for the fabrication of free-standing waveguides without\ncollapse. We show that the synthetic ommatidia can confine light and\npropagate it all the way to the tips.