Fabrication Development Of Micron Scale Retroreflector Assays Using Wet Etching

We are developing a new ultra-sensitive pathogen detection platform for rapid, point-of-care diagnostics. The platform uses micron-scale retroreflecting surfaces to allow for accurate and automated detection of virus and/or bacteria using an autonomous machine vision system. For this work, we have optimized the manufacturing processes for forming the retroreflecting patterns by switching to a negative tone resist and incorporating a wet etch in place of a liftoff step. We have eliminated low yield steps and have replaced them with a more repeatable fabrication sequence. The total number of processing steps have been reduced and repeatability has been improved, resulting in an overall 20 times increase in throughput. In parallel, we have increased the reflectivity of the structures by optimizing retroreflector pattern geometry as well as the reflective coating layer. Finally, we have also optimized a suspended retroreflector cube manufacturing approach that now integrates colored dyes for multiplexed readout.