Microfluidic optoelectronic sensor array for detection of dissolved CO2 based on halocromic dye-doped polymeric microbeads

We present a microfluidic optoelectronic sensor for detection of dissolved CO₂ in aqueous samples. The sensor contains an array of wells embedded in a microfluidic device and filled with ion-exchange polymeric microbeads doped with halocromic dyes. We have developed a simple procedure for microbeads deposition that allows incorporation of virtually any combination of halocromic dyes, providing a route for cross-reactive sensing. Due to a versatile optical arrangement, using LEDs and photodiodes, optical signals are easily translated into electronic readouts. We demonstrate the sensor ability to provide distinct responses to different concentrations of dissolved CO₂. Moreover, the sensor shows no cross sensitivity to acidity not related to dissolved CO₂.