Biography：Prof. Hui You received his PhD in MEMS in 1999 from University of Science and Technology of China, and then did postdoctoral researches in MEMS and microfluidics at Ritsumeikan University, Japan and Cambridge University, UK. In 2004 he joined Institute of Nanotechnology Exploitation (INEX) in University of Newcastle, UK as the leader of MEMS design group. He moved to Institute of System Level Integration, UK in 2008, where he worked as a PI in microfluidics and biochips. In 2010 he joined Institute of Intelligent Machines, Chinese Academy of Sciences as a professor and the leader of micro ultrasonic-fluidic systems group, and was selected as a scholar of 100 Talents Plan of CAS in 2012. In 2019 he moved to Guangxi University as the dean of school of mechanical engineering. He is a member of the council of Chinese Mechanical Engineering Society (CMES) and the council of Micro-Nano Fluidic Technology Branch of Chinese Society Micro-Nano Technology. His current interests are microfluidics, MEMS, environment monitoring equipment, biomedical instruments and cost-effective, field-portable point of care technologies.

A Microfluidic System of Gene Transfer by Ultrasound

Ultrasonic gene transfer utilizes cavitations to form reversible porosity in cell’s membrane but ultrasound does not directly act on cells. It is recognized as an ideal approach for plasmid or DNA fragment transfer due to its advantages over other DNA transferring technologies. However, most examples reported were carried out in macro volumes with conventional ultrasonic equipment, in which only average results from huge number of cells could be obtained, which is not suitable to precision analysis.  In the present study, we tried to introduce local ultrasound cavitation into the microfluidic channel to solve the problem. A MEMS ultrasonic transducer array based on piezoelectric thin film with flexible substrate was integrated with microchannels to form a microfluidic system for gene transfer. Due to the bowl shape of the MEMS ultrasonic transducer, the ultrasound generated was self-focused. Therefore, the low input voltage and power could be used to produce an acoustic pressure exceeding the cavitation threshold in a local region of the microchannel in order to reduce the damage to the cells. The cavitation in the micro channel was detected by sonochemical methods and a photoelectric non-contact detection method based on single photon detection technology. The experiments of ultrasonic gene transfection for HeLa cells were carried out successfully, which proved that the cell sonopration could be realized by using the ultrasound within the frequency band of 1~3 MHz. The experiment results confirmed that the array with more ultrasonic transducers could lead a higher transfection rate. It means that the microfluidic system may reach very high transfection rate if a good number of ultrasonic generators are used, which indicates good application prospects of the microfluidic system.