Smart Microscopy Slide for Ultrasonic Manipulation of Particles and Droplets in Wet Mounted Samples

A microscopy slide with an ultrasonic transducer attached can be used to acoustically manipulate microparticles and droplets wet mount on it. The wet mounting is done by pipetting a solution containing the particles/droplets on the slide, and then placing a coverslip on top. The coverslip is held in place by capillary forces. The manipulation is based on closed-loop, machine-vision-based tracking of the particles in an inverted microscope. An algorithm learns how the particles move in response to varying driving frequencies and uses this information to decide which frequencies need to be driven to move the particles where we want them to go. With 70 11m particles, the manipulation accuracy was 37 11m and manipulation speed 320 µm/min. These results are on par with the results we obtained previously when manipulating particles inside microfluidic chips. Wet mounting is a standard microscopy technique, and being able to acoustically manipulate particles in wet mount samples brings acoustic manipulation closer to everyday microscopy practice.