Hydrophilicity of COC Microfluidic Devices

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Hydrophilicity of COC Microfluidic Devices

Potomac can fabricate fully functional microfluidic devices in many materials such as Cyclo-Olefin Copolymer (COC). Often our customers ask us to treat the material to make if more hydrophilic.  COC is a relatively hydrophobic material that can be difficult to wet with water or aqueous solutions. However, there are several methods that can be used to increase the hydrophilicity of COC, which can improve its performance in microfluidic devices. Here are some common methods:

1. Plasma treatment: Plasma treatment is a surface modification technique that can introduce functional groups such as carboxylic acids, hydroxyl groups, or amino groups to the surface of the COC. This can increase the surface energy and hydrophilicity of the material, making it more wettable. Plasma treatment can be performed using a variety of gases such as oxygen, nitrogen, or hydrogen, and the treatment time and conditions can be optimized to achieve the desired surface properties.

2. UV/Ozone treatment: UV/Ozone treatment is another surface modification technique that can increase the hydrophilicity of COC. The treatment involves exposing the COC to UV light and ozone, which can break down the surface bonds and create new hydrophilic functional groups. UV/Ozone treatment is relatively fast and easy to perform and can be used to modify the surface of COC without affecting its bulk properties.

3. Chemical treatment: Chemical treatments such as acid etching, base hydrolysis, or grafting of hydrophilic polymers can also be used to increase the hydrophilicity of COC. Acid etching involves exposing the COC to a strong acid such as sulfuric acid, which can remove the surface layers and create new functional groups. Base hydrolysis involves exposing the COC to a strong base such as sodium hydroxide, which can create hydrophilic functional groups such as carboxylic acids. Grafting of hydrophilic polymers involves attaching hydrophilic polymer chains to the surface of the COC, which can increase its hydrophilicity.

4. Surfactant treatment: Surfactants are molecules that can reduce the surface tension of liquids and can be used to increase the wetting of COC. Surfactant treatment involves immersing the COC in a solution containing a surfactant such as Triton X-100 or Tween-20, which can adsorb onto the surface of the COC and reduce its contact angle with water.

In summary, plasma treatment, UV/Ozone treatment, chemical treatment, and surfactant treatment are all effective methods to increase the hydrophilicity of COC. The choice of method will depend on the specific application and the desired level of hydrophilicity required.

Potomac Photonics is the leader in helping customers develop and bring their microfluidic products to the markets.  We have a broad range of technologies including some of which are mentioned in the article capable of fabricating, treating and assembling microfluidic parts.  Please contact us today to discuss you application.