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Name of Experiment: application of power amplifier in microfluidic chip testing

Research Direction：microfluidic chip test

Experiment Contents: in this experiment, metabolite amino acids were taken as the research object to study the characteristics of skin upgrade microdroplet embedded amino acids.

Experiment Objective：the study on the characteristics of the microdroplet embedded in amino acids lays a foundation for the droplet microfluidic chip system in amino acid detection, high-throughput screening and directed evolutionary transformation of the corresponding production strains.

Experiment Equipment: laser, focusing objective, high speed camera, filter, photomultiplier, data acquisition card, ATA-7010 high voltage amplifier, Mitos pressure pump, silicon chip, SU-8 2025 glue, plasma cleaner, homogenizer, heating table, ultraviolet lithography machine, microfluidic chip, PDMS.

Experiment Process：

（1）construction of integrated control system for droplet microfluidic chip

The laser emits at a wavelength of 532 nm, and the laser passes through the filter to remove clutter, and then focuses to the detection point of the microfluidic chip. When the microdroplet embedded with fluorescent material passes through the detection point, it is excited to produce fluorescence, and the fluorescence reaches the spectroscope after being focused by the focusing objective. A part of the fluorescence is transmitted to a high-speed camera through a spectroscope to monitor the flow of the droplets in real time. The other part of fluorescence is received by the photomultiplier tube (PMT) through the filter, and the fluorescence signal is converted into voltage signal, which is collected by the data acquisition card and analyzed by LabVIEW software.The high voltage amplifier is used for the deflection of the microdroplet. When the detection signal of the target microdroplet exceeds the threshold set for sorting, the analysis software applies the deflection voltage to the microdroplet through the high voltage amplifier and electrodes on the microfluidic chip.Due to the effect of dielectric electrophoretic force, the target droplets will be deflected and flow to the sorting channel to be collected.

Experiment Result:

（1）The diameter of the generated microdroplet is controllable, the size is uniform and stable, the reaction system in the microdroplet is small, and a lot of reagents can be saved.

（2）The microdroplets can be stable for a long time to meet the time requirements of reagent reaction or cell culture.

（3）The embedded material of the microdroplet exists stably in the test microdroplet, and there is no cross contamination between the microdroplet, which will not affect the fluorescence detection and sorting of the microdroplet in the later stage.

（4）The screening flux of microdroplets was up to 600 droplets per minute. These experiments provide the possibility of high-throughput screening for the detection and analysis of cellular secretions such as enzymes and amino acids and the screening of corresponding production strains, and lay the foundation for the application of droplet microfluidic chip in directed evolution.

The performance of the amplifier in the experiment: apply a deflection voltage to the microdroplet, use for deflection of microdroplets.

The reason to choose the amplifier: the bandwidth and amplification meet the requirements, and the experiment result is stable.