Biomedical sensing applications, including breath analysis, contribute to increasing the amount of electronic waste, as the sensors are frequently disposed, due to hygienic considerations. Consequently, the development of sustainable sensor solutions is crucial. Here, a Chitosan-based sensor proposed for the utilization in biomedical applications is presented. The sensor is fabricated on a bio-sourced and biocompatible thermoplastic polyurethane substrate, and its response to Acetone vapor is studied. The use of Chitosan, a natural biopolymer, together with additive manufacturing technologies make this sensor sustainable, while the use of biocompatible materials makes it well-suited for biomedical applications. The sensor shows a good linearity in the range between ambient Acetone concentrations of 0 - 73 ppm with relative changes of 0.42% per ppm and 2.75% per ppm at ambient humidities of 50 +/- 5%rH and 80 +/- 5%rH, respectively.