Microfluidic device directs zebrafish to swim to imaging platform

Zebrafish are common animal models for research involving vertebrate biomechanics, developmental biology, and cardiovascular development because they are transparent: Their blood vessels, internal organs, and developing embryos are visible with a low-power microscope. However, the mechanical pumping needed to transport anesthetized larvae through narrow channels to a microscope stage can damage their bodies. Now a team of researchers has reported a device in Biomicrofluidics that enables zebrafish larvae to swim to an imaging location.

The team wanted to utilize a known reflex in 3-day-old zebrafish larvae that causes them to swim in the direction of movement detected by their whole field of vision.

They built a network of microfluidic channels and chambers on top of a liquid crystal display (LCD). The LCD panel displayed animations of moving black and white stripes underneath a chamber holding 5-day-old zebrafish larvae. Larvae followed the moving stripes and swam forward into a central chamber, which was connected to three imaging chambers.

Next, the researchers displayed the animation underneath one of the channels exiting the central chamber to direct the larvae to swim into an imaging chamber. They also guided the fish to swim back to the central chamber by reversing the direction of movement in the animation. Transporting larvae from the first chamber to the last chamber took about half a second.

The device can be integrated with existing microscope equipment, and it enables researchers to observe the natural behavior of larvae because they can be transported without anesthesia.

Source: “A noninvasive light driven technique integrated microfluidics for zebrafish larvae transportation,” by Karthick Mani, Yu-Che Hsieh, Bivas Panigrahi, and Chia-Yuan Chen, Biomicrofluidics (2018). The article can be accessed at https://doi.org/10.1063/1.5027014 .