Gas selective electrodes mimicking human olfactory receptor cells

The human olfactory receptors are specialized to a narrow range of odorants. Ideally, an artificial olfactory sensor should possess one type of specific receptor to recognize a limited number of gaseous molecules. However, current artificial olfactory receptors remain constrained by poor selectivity due to the absence of specific molecular recognition mechanisms. Here, we developed biomimetic gas selective electrodes (GSEs) featuring a novel sensing mechanism, which leverages an enzyme/quantum dot (QD) framework to achieve molecularly specific recognition through the intrinsic chemical binding sites of the enzyme. Several enzymes, such as superoxide dismutase 1 (SOD1), polyphenol oxidase (PPO), formaldehyde dehydrogenase (FALDH), and alcohol oxidase (AOx), are immobilized on QDs for the selective detection of hydrogen sulfide, phenol, formaldehyde, and ethanol, respectively, across a background of 20 gases. QD surface ligands enhance sensitivity by stabilizing the QD-enzyme interface and promote electron transduction, thereby enhancing the overall sensing sensitivity. With this architecture, the GSEs exhibit excellent sensitivity and selectivity, achieving limits of detection (LODs) down to 3.27, 8.58, 27.7, and 51 ppb, even in mixed-gas environments. Multiscale simulations reveal the recognition mechanisms, and an equivalent circuit model guides sensitivity modulation. This biomimetic strategy advances artificial olfactory sensors for applications in medical diagnostics, environmental monitoring, wearables, and robotic olfaction. Download: Download high-res image (165KB) Download: Download full-size image