Atmospheric pressure plasma-enhanced chemical vapor deposition (AP-PECVD) of functional coatings for electrochemical sensing
Biosensor and lab-on-chip devices are revolutionizing modern healthcare as they offer great potential for point-of care diagnostics and various bioanalytical applications. A key challenge in biosensor technology is the development of stable, reliable and reproducible interface chemistries for immobilization of the bioreceptors onto the sensor substrate. At imec, we have explored different surface chemistries, mainly self-assembled monolayers, to ensure a covalent binding of the receptors to biosensor devices. Vapor-phase processes offer a good control of the deposition reaction with less chemical usage and result in uniform coatings in micro-structured substrates or microfluidic channels hereby enhancing the integration compatibility with standard CMOS processing flows. The current limitation of standard CVD and MLD processes is imposed by the low vapor pressure of the precursors that require a too high temperature budget for volatilization. Therefore, in this PhD we want to explore the use of plasma-based depositions of functional coatings in collaboration with the Molecular Plasma Group (MPG)*. MPG offers a technology called atmospheric pressure plasma-enhanced chemical vapor deposition. The use of inert gases such as argon, helium and nitrogen and the use of small quantities of energy at low operating temperatures makes this method environment-friendly and opens the possibility to deposit precursors with a high vapor pressure and to co-deposit different reagents, including intact biomolecules into the deposited layer. By using this technology, I want to deposit uniform thin layers to produce biosensors in a CMOS environment. In view of the large variety of biosensors that is currently investigated, it is likely that no single coating method will suffice for all applications. In order to make the results of this work as widely applicable as possible, the plasma processes will be developped to allow electrochemical detection of inflammatory markers (e.g. C-reactive protein, Tumor Necrosis Factor-α) and detection of metabolites (e.g. glucose, lactose) on selected electrode materials. I will explore the wafer level uniformity, stability and reproducibility, the ability to co-deposit mediators, small molecules and antibodies, the possibilities for area-selective deposition using standard CMOS patterning technologies and/or using optimized nozzle geometries during plasma deposition and finally showcase multiplexed biosensing.