OpenWSI: an open-source, low-cost, and high-throughput whole slide imaging system via single-frame autofocusing

Recent advancements in whole slide imaging (WSI) have moved pathology closer towards digital practice. Existing systems require precise mechanical control and the cost is prohibitive for most individual pathologists. Here we report an open-source WSI system, termed OpenWSI, which is built using off-the-shelf components including a programmable LED array, a photographic lens, and a low-cost computer numerical control (CNC) router. Different from conventional WSI platforms, our system performs real-time single-frame autofocusing using color-multiplexed illumination. For axial positioning control, we perform coarse axial adjustment using the CNC router and precise adjustment using the ultrasonic motor ring in the photographic lens. By using a 20X objective lens, we show that the OpenWSI system can acquire images of a 225-mm² area in ~2 mins, with an imaging throughput comparable to existing high-end platforms. We have also provided an open-source implementation protocol for the broad research community. The reported system offers a turnkey solution to transform the high-end WSI platforms into one that can be made broadly available and utilizable without loss of capacity.