Chemically resistant microfluidic valves from Viton® membranes bonded to COC and PMMA

We present a reliable technique for irreversibly bonding chemically inert Viton® membranes to PMMA and COC substrates to produce microfluidic devices with integrated elastomeric structures. Viton® is widely used in commercially available valves and has several advantages when compared to other elastomeric membranes currently utilised in microfluidic valves (e.g. PDMS), such as high solvent resistance, low porosity and high temperature tolerance. The bond strength was sufficient to withstand a fluid pressure of 400 kPa (PMMA/Viton®) and 310 kPa (COC/Viton®) before leakage or burst failure, which is sufficient for most microfluidic applications. We demonstrate and characterise on-chip pneumatic Viton® microvalves on PMMA and COC substrates. We also provide a detailed method for bonding fluorinated Viton® elastomer, a highly chemically compatible material, to PMMA and COC polymers. This allows the production of microfluidic devices able to handle a wide range of chemically harsh fluids and broadens the scope of the microfluidic platform concept

Autonomous microfluidic sensors for nutrient detection applied to nitrite, nitrate, phospate, manganese and iron

We present the design, fabrication, analysis and characterisation of autonomous high accuracy and sensitivity microfluidic nutrient sensors. A stand-alone sensor platform with integrated sub-systems is demonstrated, which is portable and capable of in-situ reagent-based nutrient analysis. The system is based on a low cost optical detection method, together with an automated microfluidic delivery system that is able to detect nitrite (e.g.) with a Limit of Detection (LOD) of 14nM. The platform was operated in-situ at Southampton Dockhead for 37 hours, performing 284 measurements