Preparation And Integration Of Sensor Device In Microfluidic Chip System

In the21st century, analytical science has got a rapid progress, one increasingly obvious trend of them is the miniaturization of chemical analysis equipment. Notably, Micro Total Analysis System has attracted much attention due to its distinct advantages. Nowadays, Microfluidics has been considered as a very important technique for both experimental and daily analysis. As the experimental platform that permits highly efficient and high-throughput detection, microfluidic chip has revealed a cornucopia of both fundamental research and practical applications. Microfluidic chip has the characteristics of high efficiency, low consumption, high-throughput, and integration, it also has the ability to handle multiple reactions and samples. Take advantages of these unique properties mentioned above, microfluidic technology is widely used in many areas such as chemistry, medicine, biology, optics, information, military, anti-terrorism, pharmaceutical testing and so on.With the rapid development of the microfluidic chip, the integration of functional devices inside a microfluidic channel has atrractted a lot of attentions and concerns. However, traditional planar means, such as potolithography, are disable in3D fabrication within a microfludic channel. In our work, femtosecond laser fabrication is used to solve this problem. Femtosecond laser micro-nano fabrication is a powerful three-dimensional processing platform; it not only meets the requirements of accuracy, resolution, and size, and also exhibits great potential in designable3D fabrication. With the help of femtosecond laser micronanofabrication technique, various microdevices could be readily designed and fabricated.As a proof of concept device, we designed a microsensor inside a microfluidic chip system. In our work, SnO2has been chosen as a humidity sensitive material, it is well known that SnO2is an n-type semiconductor material. Firstly, we prepared the photosensitivity of the sol. Then, SnO2sol was direct-written by a focus femtosecond laser beam. The regions irradiated by laser became insoluble in acetone. So after development, the designed microstructures were obtained. Finally, In order to get the pure oxide semiconductor, the microstructures were calcined at high temperature conditions(500℃) for2h. The humidity sensing performance of the as-prepared micro-sensor has been tested with care.At last, we designed a test circuit, to detect the humidity changes in the microfluidic channel. The overall circuit was based on the microcontroller STC89C52. The circuit worked as follows:The constant current source provided the operating current for the sensor. After treated properly, the signal out from microsensor was converted to a voltage signal which was suitable for analog-to-digital converter ADC0804. The digital information converted by ADC0804finally was displayed on the LCD screen in LCD1602.