Integrated Sample Injection Chip for Micro-HPLC

In this paper we present a novel sample injection chip. Microvalves and microchannels are integrated on the chip. The valve is a passive lowpass valve that allows a liquid flow at a low flow rate and prohibits it when the flow rate exceeds a threshold. We can control the injection volume by changing the channel design. The chip consists of a channel substrate, an upper valve substrate and an under valve substrate. These substrates are separately fabricated and bonded by using MEMS techniques. The chip, not to leak at a pressure difference of 5.0 MPa, was successfully applied to high performance liquid chromatography (HPLC). A specific volume of sample (100 nl) was injected to the HPLC column. The results show that the sample injection chip has the possibility of being used in the micro-HPLC systems.