Coating of Point-of-Care devices as a Key Enabling Technology

Point-of-Care (PoC) devices enable the performance of medical tests in the vicinity of the patient, instead of in a clinical environment. Microfluidic devices can enhance the development of PoC devices for more complex diagnostic tests. In this process, the use of plastic microfluidic chips would be preferred from a cost perspective, but their use leads to a number of technological challenges. In the Coat PoCKET project, Surfix and Micronit Microtechnologies combine their forces to successfully overcome these challenges.


The main goal of the Coat PoCKET project is to develop a disposable microfluidic chip to create a complex Point-of-Care assay using coatings to improve its performance. The chip is made of a plastic material (COC, cyclic olefin co-polymer). Like most plastics, the material in its original form is only very slightly hydrophilic to hydrophobic and therefore requires a special coating in order to initiate and sustain filling of microfluidic channels by capillary force. Additionally, to create an autonomous microfluidic device that doesn’t require the use of an external pump, the chips will be equipped with capillary burst valves to be able to introduce a multitude of liquids into the device in arbitrary order.


COC is widely used in the fabrication of plastic microfluidics. However, plastics are typically hydrophobic, foul easily and therefore can affect test results. In order to optimize the flow properties of the chip, a hydrophilic nanocoating was applied in the microfluidic channel. Hydrophobic patches were integrated to create barriers. The hydrophilic coating facilitates fast and reliable capillary filling, while the hydrophobic patches increase the holding strength of the capillary valves. Finally, the devices are sealed with a second coated COC substrate, which is equipped with thin film electrodes. The coating is resistant to high temperatures, while unreacted areas remain bare COC, therefore compatible with thermal compressing bonding.


The low-cost thermoplastic, coated chip has integrated electrostatically-actuated capillary burst valves. The valves have no moving elements and simply rely on an abrupt increase in the cross-section of a microfluidic channel, causing the capillary stream to stop. Applying a voltage between two electrodes, triggers the valve and causes the flow to recommence. Micronit developed this technology, enabling the sequential capillary flow of liquids in microfluidic devices without the use of external pumps.


The chips were manufactured and bonded by Micronit Microtechnologies. The coating process was performed by Surfix, expert on (localised) modification of glass and plastic surfaces. This project was supported by a grant from the European Regional Development Fund (Project number PROJ-00630). In our webstore you can find hydrophobic and hydrophilic droplet generators.