PhD position on hermetic packaging of microfluidic sensor chips without glue or elastomers for ventilators and multi-infusio...

In medical equipment, many different gas flows need to be controlled, including gases such as O2, CO2, He, Xe, Kr, Ar, Ne, N2, N2O, and H2, all in varying concentrations ranging from 0 – 80%. Traces of up to 500 ppm of NO, CO, and H2S could occur in the gas mixture and should be detected. Some applications may require the use of gaseous anaesthetic agents such as isoflurane and desflurane. This also imposes demands on the chemical compatibility of the materials used.

In multi-infusion systems, the flow meters need to measure the amount of liquid pharmaceuticals as well as multiparameter measurements to measure the composition and parameters of the pharmaceuticals. Typical liquids to be administered are noradrenaline, dopamine, dobutamine, morphine, insulin, glucose and saline solution.

Whereas the flow sensors themselves are reaching the point that they can meet the required performance, an essential final problem still needs to be resolved. Namely, the connection of the flow sensor chip to the outside world without elastomer seal or glue, since these wetted materials can pose unacceptable risks in these applications. In breathing systems, elastomers can release volatile substances (VOCs) in the breathing gas path that the patient inhales directly. With multi-infusion systems, unwanted interactions between the glue and the different medications can occur, causing the glue to dissolve or the medication to become ineffective. This issue limits the application of microfluidics in the aforementioned demanding fields. This project aims to find methods to eliminate these urgent packaging issues. As the demand for advanced ventilators and multi-infusion systems grows, finding a suitable “glueless” sealing method will become a key solution in bringing MEMS based microfluidic flow meters to the medical and other markets, driving further innovation in healthcare and related technologies.

The goal of this project is to find a reliable packaging technique for silicon chips with embedded microfluidic channels that does not involve the use of glue or elastomer seals. The project will focus on microfluidic channels with a channel wall of low-stress silicon-rich silicon nitride. The proposed research aims to study the fundamentals of bonding glass or metals to silicon nitride coated silicon wafers as well as accessing the feasibility of using these bonding methods for MEMS-based microfluidic sensor packaging.

The targeted output of the project is a glueless sealing technique which allows to hermetically seal the fluidic channels of a MEMS-based microfluidic sensor to a fluidic adaptor. The seal shall be able to withstand pressures up to 30 bar at a temperature range between -20°C and 70°C. To extend the applicability of the microfluidic sensor, only inert materials for the seal and the adaptor will be considered.

The main challenges are (1) exploring the most promising bonding techniques that should be investigated, (2) carry out bonding experiments and analyse the results (3) design, fabrication and packaging of actual sensor chips in the MESA+ cleanroom and (4) evaluation of the resulting performance in our MEMS measurement lab.

The PhD candidate will work at the Integrated Devices and Systems (IDS) group within the Faculty of Electrical Engineering, Mathematics and Computer Science (EEMCS) at the University of Twente in Enschede, the Netherlands. You will carry out the research at the University of Twente, with guidance from senior scientists and support from a senior engineer. Various teaching activities in your field of expertise may take up to 20% of your time.