μdroPi: A Hand-Held Microfluidic Droplet Imager and Analyzer Built on Raspberry Pi

We built a low-cost and hand-held device to image and analyze microfluidic droplets mainly for educational/teaching purposes in laboratory settings of universities. The device was assembled based on a Raspberry Pi with a camera attached on the back and an LCD screen on the top. We evaluated the performance of this device to capture images and videos to visualize high-throughput droplet generation in a microfluidic device. The qualities of imaging resolution and speed were sufficient for us to perform subsequent droplet analysis quantitatively through automatic image possessing. Droplet characteristics including droplet size, volume, and dispersity, as well as droplet intensity, have been measured, showing the potential of this device to analyze droplet-based assays. Most importantly, in addition to learning the knowledge and principles from classroom lectures, students can thus gain practice of using an advanced, state-of-the-art technology in a laboratory course. It will also open up opportunities to train students with skills of interdisciplinary thinking and learning.