China University of Science and Technology successfully developed handheld digital pipettes with nano-upgrade accuracy

[ China Instrument Network Instrument Development ] Li Baoqing, associate professor of the Micro-Nano Engineering Research Office of the School of Engineering Science, University of Science and Technology of China, and Pan Tingrui, a professor at the University of California, Davis, proposed and implemented a liquid migration technology with nano-adjusted precision. The technology combines the common pipette technology and the microfluidic printing technology, and the microfluidic chip can control the droplets of the nanoliter volume, and the single droplet is the smallest unit, thereby realizing the absorption and distribution of the nano-adjusted precision liquid. The result is based on High-Precision Digital Droplet Pipetting Enabled by a Plug-and-Play Microfluidic Pipetting Chip, published in the engineering journal Lab on a Chip (2018, 18, 2720-2729), and is included in the current cover (Front Cover) .

Digital Drop Pipette for Micro Volume Liquid Manipulation

In biological and chemical applications, manipulation of liquid reagents is one of the most basic operations. Pipettes are currently the most widely used portable liquid handling instrument. It is based on the pneumatic piston principle for aspiration and liquid separation. For this mode of operation, when a small amount of liquid is removed, for example, when the volume of the liquid is less than 1 microliter, the error sharply rises, and the removal accuracy is difficult to ensure. This paper proposes a new digital drop-type pipetting method that is completely different from the existing working principle. The resolution of the current pipette is increased by more than two orders of magnitude, and the error of the liquid handling of the sub-microliter system can be reduced by two. Magnitude.

In this paper, the authors use microfluidic impact printing to produce highly consistent nanoliter droplets. Different from the microfluidic method of intra-chip droplets, the position of droplet printing can be selected at will, and the key point is that printing can be performed according to the number of droplets required. A single nanoliter droplet is used as the most basic unit, the minimum resolution, to achieve different doses of liquid distribution in a digital manner by accumulating the number of individual droplet units. In this nano-precision pipette, a microfluidic chip with liquid is tapped by a small printing device to realize the generation of micro-droplets during the tapping process. Combined with traditional pipettes and new microfluidic impact printing technology, this new pipette not only has the high resolution and high precision that traditional pipettes do not have, but also the operability of sucking and dispensing liquids. Traditional hand-held pipettes are as easy to use. The device can be widely used in a variety of high precision liquid handling experiments. For example, the device can be directly diluted to obtain different concentrations of reagents, instead of the previous serial dilution to produce a concentration gradient, which is not only simple to operate, saves expensive reagents, and more importantly avoids large error accumulation during continuous dilution.

In recent years, the research team has focused on microfluidic printing new technology and researched new methods for high-throughput biochemical reactions using micro-droplet arrays. A series of fruitful results have been obtained. The article has been published on Lab on a chip (2017, 17, 2198). , Back Cover), Biomicrofluidics (2015, 9, 054101; 2018, 12, 034107).

Mao Yuzhen, a doctoral student at the School of Engineering Sciences, is the first author of the paper. Li Baoqing and Pan Tingrui are co-authors of the paper. This work was supported by the National Natural Science Foundation and the Overseas and Hong Kong-Macau Cooperation Fund.

(Original title: China University of Science and Technology successfully developed a handheld digital pipette with nano-upgrade accuracy)