Digital Microfluidic-based Electrochemical Whole-cell Biosensor For Arsenite Detection

With the development of microfluidic systems,the development of lab-on-a-chip(LOC)equipment for the biochemical field has become a trend.In order to conduct a complete biochemical analysis on the device and commercialize the technology,researchers have invested a lot of time and energy.Among the existing microfluidic systems,the dielectric wetting(EWOD)digital microfluidic(DMF)technology has received widespread attention in the real-time detection field due to its high flexibility and ability to process multiple samples simultaneously.However,due to various reasons,the current DMF chip is still far from commercial application.In order to solve this practical problem,this paper reports an integrated portable electrochemical digital microfluidic system suitable for real scenes.We take arsenic ion pollution in drinking water as an example,combined with high-sensitivity whole-cell biosensors to achieve on-site online detection of pollutants.From the perspective of practical application,through the selection of chip manufacturing procedures and materials,we have developed DMF chip structures suitable for different application scenarios,including glass-based gold electrode array chips for laboratory use,indium tin oxide(ITO)electrode array chips for integrated optical devices,disposable low-cost screen-printed electrode array chips,and printing produced by mature commercial integrated circuit manufacturing processes Circuit(PCB)chip.At the same time,a control system based on the Arduino development board was designed and developed,and the corresponding host computer program was written for it,so that the entire control device has the advantages of miniaturization and handheld,which greatly expands the application scenarios of DMF chips.We also integrated the portable electrochemical detection device with the DMF system and built a portable electrochemical digital microfluidic detection platform.Innovatively combining a whole-cell biosensor with an electrochemical signal output with this platform,and successfully achieved high-sensitivity detection of arsenite in drinking water.The detection limit is as low as 16 nM,which is far below the WHO standard of 133 nM.(10 ppb).The recovery of this sample was confirmed by the actual sample spiked recovery experiment,with a recovery rate of 97.5%to 100%.It has strong anti-interference and good stability.The entire design not only solves the pain points in the actual application process of the whole-cell biosensor,but also provides new ideas and application directions for the fields of environmental monitoring,food safety,instant diagnosis,and disease screening.