Coat PoCKET

background

There is a strong demand for the development of new technologies for point-of-care (PoC) diagnostic testing. PoC devices allow medical tests to be performed in the vicinity of the patient instead of in a clinical laboratory. Compared to current solutions, microfluidic devices promise to enable the development of PoC devices for more complex diagnostic tests. From a cost perspective, the use of plastic microfluidic chips is preferred, but their commercial success requires a number of technological challenges to be solved. 


In Coat PoCKET, Micronit Microtechnologies and Surfix join forces to bring the technology for fabricating advanced point-of-care diagnostic tests to the next level.




PROJECT OUTLINE

Coat PoCKET aims at the development of a demonstrator bioassay, based on a polymer (COC) microfluidic chip enabling sequential flow of liquids without using external pumps. This is achieved through an innovative combination of:

• passive flow control by electrostatically actuated capillary burst valves (Micronit)
• patterned hydrophobic, hydrophilic and antifouling nanocoatings by local surface modification (Surfix)

Aiming at high volume production, scalable techniques are used for the fabrication of chips containing the functionalities required for controlling the flow of multiple liquids. For this purpose, capillary valves are integrated on the chip, relying on an abrupt increase in the cross-section of a channel to stop capillary filling. The flow can be restarted by applying an electrostatic pulse.

To optimize the flow properties of the chip, a patterned nanocoating consisting of hydrophilic and hydrophobic areas is applied to the channel surface. The hydrophilic nanocoating facilitates fast and reliable capillary filling, while hydrophobic patches increase the holding strength of the capillary valves.

This combination of functionalities facilitates complex fluid control and enables multistep bioassays to be performed on a single chip without external pumps.




NANOCOATING DEVELOPMENT

COC is a thermoplastic polymer which is popular for manufacturing microfluidic devices because of its optical transparency and chemical inertness. However, COC is also rather hydrophobic, with a water contact angle of 95-100°.

For local hydrophilisation of COC, a 3D nanocoating was developed which decreases the contact angle of COC to 45°. For the valve area, a hydrophobic 3D nanocoating was developed which leads to enhanced hydrophobicity of COC (contact angle 125°). It was shown that both coatings can be patterned on the same surface, leading to surfaces with a large contrast in wettability. Moreover, it was demonstrated that the nanocoatings are compatible with typical conditions for thermal compression bonding.




Condensation of water on a COC surface with a patterned hydrophilic nanocoating







Coating of microfluidics

The hydrophilic nanocoating was successfully patterned in microfluidic channels, and coated devices could be bonded normally by thermal compression bonding.