Polydiacetylene-embedded microbeads for colorimetric and volumetric sensing of hydrocarbons

Rational design of a hydrocarbon sensor that enables visual differentiation of saturated aliphatic hydrocarbons (SAHCs) is very difficult owing to the lack of useful functional groups that can interact with the sensor system. Here, we report a microbead embedded with polydiacetylene that undergoes faster swelling and faster blue-to-red color change in response to the hydrocarbons of shorter alkyl chains. Accordingly, visual differentiation among n-pentane, n-heptane, n-nonane, and n-undecane was readily achieved. By taking advantage of the collective effect, construction of a sensor system with amplified response was possible. Combination of microfluidic technology (for bead preparation), PDMS (swellable polymeric matrix), and polydiacetylene (colorimetric material) was key to enabling this unique hydrocarbon sensor.