Development of an Enzyme-Based Electrochemical Acetone Gas Sensor Printed on a Porous Polyimide Film

Acetone is a key ketone body whose concentration reflects metabolic states such as fasting, exercise, and diabetes. In this study, we report an enzyme-based electrochemical acetone gas sensor fabricated by screen printing on a porous polyimide film. The porous substrate permitted gas permeation while suppressing liquid penetration, enabling stable electrochemical measurements. The working electrode was prepared using a MgO-templated carbon graft polymerized with glycidyl methacrylate (GMgOC), which provides reactive epoxy groups for enzyme immobilization. A compact sensor was constructed by sealing a mediator-containing electrolyte within a polydimethylsiloxane chamber. The sensor exhibited concentration-dependent responses to acetone gas in the range of 50-1000 ppb, covering typical human skin gas levels. The limit of detection was 75 ppb and the limit of quantification was 250 ppb, with a linear range of 50-100 ppb. This ppb-level sensitivity is considered to be associated with the adsorption and concentration of acetone within the porous GMgOC structure. These results suggest the potential applicability of this approach for noninvasive monitoring of skin acetone gas, although further validation including selectivity testing and real-sample measurements is needed.