The emerging need to process tiny liquid samples and reagents has been growing in a variety of medical and biological fields. And this requires an easy-to-use and portable solution with low capacity and high precision liquid handing.

  Figure 1. Digital pipette for small volume liquid control. (Image by LI Baoqing and PAN Jingrui)

To this end, a new liquid removal technology with nano-sacle accuracy has recently been put forward and realized by LI Baoqing, an associate professor at the University of Science and Technology of China, and PAN Jingrui, a professor from the University of California, Davis.

The commercialized micropipettes, established on the piston-driven air displacement mechanism, can effectively handle liquid samples between 1 µL and 1000 µL. While the deviation from the targeted volume could be more than 20% when the volume goes down below 1µL. In this report, LI and PAN investigated a new digital droplet pipetting method inspired by the microfluidic impact printing (MIP) principle. It consists of a plug-and-play and disposable microfluidic cartridge with a high-precision loading and dispensing nozzle, driven by a programmable electromagnetic actuator for on-demand dispensing of nanoliter droplets. The prototype has a great performance, the variation of the dispensed volume has been successfully reduced from 49.5% to 0.6% at 0.1 µL scale, as compared to its commercial counterparts.

(Written by DENG Weiting, edited by YANG Xinqi, USTC News Center)