A biodegradable, all-polymer micromotor for gas sensing applicationsElectronic supplementary information (ESI) available: Fig. S1-S3 and Videos S1-S4. See DOI: 10.1039/c6tc00971a

In this paper, we report an all-polymer micromotor, which consists of a biodegradable polymer main body (polycaprolactone) and a natural enzyme 'engine' (catalase). Not only can this micromotor be self-propelled in the presence of a fuel, it also exhibits fluorescence gas sensing properties toward HCl and NH 3 gases through the introduction of a dye molecule. As compared to the static one, the micromotor shows a faster response which can be attributed to the solution mixing process induced by the continuous motion. In addition, due to the biodegradability of polycaprolactone, this micromotor is capable of slowly degrading in solution. The features shown in this study, such as the metal-free structure and the gas-sensing capability, make the current micromotor potentially attractive for environmental monitoring applications. We report a biodegradable, all-polymer micromotor which can be utilized for gas sensing applications.