Integrated Semiconductor Sensor with Automatically Controlled Microfluidic Chip for Blood Monitoring

Recently, microfluidics has been applied for various kinds of field, especially in biomedical and disease diagnostic field. Among them, there will be a great commercial potential and a huge contribution for human life. On the other hand, semiconductor sensors such as Electrolyte-Insulator-Semiconductor (EIS) and Ion-Sensitive-Field-Effect-Transistor (ISFET) have been widely investigated in recent thirty years. Due to the high sensitivity, good robustness, and compatibility of mass-produced process, the semiconductor sensor has great opportunity to be massively produced for biomedical and chemical sensor. However, the investigation about integrating semiconductor sensor with microfluidic system is still in the beginning. Within two years, the goal of the proposal is to integrate the semiconductor sensor with microfluidic system as a biochip which can achieve multi targets detection and automatically-controlling fluid in micro-channels. The proposed chip can be used to detect the concentration of glucose, urea, potassium ion, and sodium ion in bio-fluid. In the first year, we are going to design and fabricate this integrated biochip which has EIS or ISFET semiconductor sensors and some active microfluidic components, including micro-pump, micro-valve, and micro-mixer. Moreover, the reference electrode (Ag/AgCl) will be miniaturized and integrated in the chip. The proposed biochip has many advantages including multi-target detecting, portable, automatically sample loading, and less sample-consuming. On the other hand, the immobilization of enzyme on semiconductor sensor can extend the detection capability for more targets in bio-fluid. However, when a sensor is immobilized with enzyme, it becomes difficult to integrate with microfluidic system and the preservation of enzyme in the chip is also a problem. In the second year, in order to solve the problem of integration of fabrication process and extent the number of sensing targets, we are going to develop a novel method for loading and immobilizing enzyme on the surface of semiconductor sensor. The strategy is to utilize emulsion technique with microfluidic chip and generate alginate micro-spheres which encapsulate enzyme. When the detection process needs the enzyme to catalyze reaction, the alginate micro-spheres can be injected into microfluidic chip and fixed by using micro-structures fabricated in the chip. Besides, magnetic beads conjugated with enzyme can also be used to carry enzyme into microfluidic chip. The magnetic bead can be fixed on the surface of semiconductor sensor by using magnet locating under the sensor. These two strategies can help to solve the problem that the enzyme cannot preserve in the microfluidic chip for a long time. Furthermore, they can provide the capability of detecting unlimited numbers of target when changing different kinds of encapsulating enzyme.

Project ID:PB9911-0342
External Project ID:NSC99-2218-E182-005