Paper‐Based, Chemiresistive Sensor for Hydrogen Peroxide Detection

Detecting hydrogen peroxide (H 2 O 2 ) as the side product of enzymatic reactions is of great interest in food and medical applications. Despite the advances in this field, the majority of reported H 2 O 2 sensors are bulky, expensive, limited to only one phase detection (either gas or liquid), and require multistep fabrications. This article aims to address some of these limitations by presenting a 3D printable paper‐based sensor made from poly(3,4‐ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) decorated with horseradish peroxidase, an enzyme able to interact with H 2 O 2 . Unlike most electrochemical PEDOT:PSS‐based H 2 O 2 sensors with voltametric or potentiometric mechanisms, the sensing mechanism in this technology is impedimetric, significantly simplifying the fabrication process. Here, the resistance of sensors proportionally changes with H 2 O 2 concentration upon exposure to liquid or gas with a linear trend within the range of 61.3 × 10 −9 and 61.3  ×  10 −6 m H 2 O 2 . The observed correlation between the resistance and H 2 O 2 concentration is highly dependent on the level of integrated enzyme, suggesting the direct contribution of horseradish peroxidase in the co‐redoxing of PEDOT:PSS in the presence of H 2 O 2 . Raman and UV–vis spectroscopies also confirm the structural change of PEDOT in the presence of H 2 O 2 which is facilitated by the enzyme.