Ultralow-Power Single-Sensor-Based E-Nose System Powered by Duty Cycling and Deep Learning for Real-Time Gas Identification

TL;DR

This paper introduces an ultralow-power, single-sensor e-nose system utilizing duty cycling and deep learning for rapid, real-time gas identification, significantly reducing power consumption while maintaining high accuracy.

Contribution

It presents a novel single-sensor e-nose design with duty cycling and deep learning, achieving low power consumption and fast gas detection, unlike traditional multi-sensor systems.

Findings

Achieved 93.9% classification accuracy for five gases within 30 seconds.

Reduced power consumption by up to 90%, down to 160 μW.

Successfully implemented on wafer-level microfabrication processes.

Abstract

This study presents a novel, ultralow-power single-sensor-based electronic nose (e-nose) system for real-time gas identification, distinguishing itself from conventional sensor-array-based e-nose systems whose power consumption and cost increase with the number of sensors. Our system employs a single metal oxide semiconductor (MOS) sensor built on a suspended 1D nanoheater, driven by duty cycling-characterized by repeated pulsed power inputs. The sensor's ultrafast thermal response, enabled by its small size, effectively decouples the effects of temperature and surface charge exchange on the MOS nanomaterial's conductivity. This provides distinct sensing signals that alternate between responses coupled with and decoupled from the thermally enhanced conductivity, all within a single time domain during duty cycling. The magnitude and ratio of these dual responses vary depending on the gas type and concentration, facilitating the early-stage gas identification of five gas types within 30 s via a convolutional neural network (classification accuracy = 93.9%, concentration regression error = 19.8%). Additionally, the duty-cycling mode significantly reduces power consumption by up to 90%, lowering it to 160 $\mu$W to heat the sensor to 250$^\circ$C. Manufactured using only wafer-level batch microfabrication processes, this innovative e-nose system promises the facile implementation of battery-driven, long-term, and cost-effective IoT monitoring systems.