Microfluidic Device for Particulate Matter Detection Using Continuous Flow Impact Electrochemistry

A long-standing challenge in lab-on-chip and biomicrofluidic sensing modes is the formation of reliable, leak-free bonding on the surface of wafers or CMOS chips having sensing electrodes typically formed by thin film metal deposition. This challenge is particularly evident in the design of polydimethylsiloxane (PDMS) flow channels for electrochemical analysis where the need for high-density electrodes increases the number of metal-PDMS interface points. This work presents a fabrication method for creating leak free bonding of PDMS on Au electrodes by coating the substrate in a low-temperature plasma enhanced chemical vapor deposited dielectric material, thereby exposing only the sensing area within the channel. Furthermore, this fabrication process was used to create the first-known impact electrochemistry flow cell capable of continuous measurement of air-borne particulate matter using microfluidics over a surface containing microfabricated gold electrodes. Functionality of the device for air pollution monitoring was validated by detecting black carbon particles using impact electrochemistry at 0.8V.