Graphene Heterojunction Gas Sensor With Zero-Power Photocurrent Detection
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Solution Overview
Problem
Conventional gas sensors face limitations in minimizing power consumption due to the need for a driving voltage to measure resistance changes, making them unsuitable for applications in IoT devices where energy efficiency is crucial.
Innovation Solution
A zero-power detecting sensor utilizing a graphene-based vertical heterojunction structure that generates photocurrent in response to light, allowing chemical substance detection without power consumption by changing the Fermi energy level and photocurrent based on adsorbed or desorbed substances, with catalyst materials like Pd or Pt used for specific gas detection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a driving voltage is applied to measure resistance change in conventional gas sensors, then chemical substance detection is achieved, but power consumption increases
Solution Approach 1:
The patent replaces the electrical resistance measurement system with an optical detection system. Instead of applying voltage to measure resistance changes, the sensor uses light irradiation to generate photocurrent in the graphene-light absorbing layer heterojunction, eliminating the need for driving voltage and achieving zero-power operation while maintaining detection capability
Solution Approach 2:
The patent changes the detection parameter from electrical resistance to photocurrent generation. By utilizing the photoelectric effect and heterojunction properties, the sensor detects chemical substances through changes in photocurrent magnitude caused by Fermi energy level shifts when chemicals adsorb onto graphene, thereby eliminating continuous power consumption
2Measurement precision
If conventional resistance-type gas sensors are used, then chemical substance detection is achieved, but device usage time is limited due to power consumption
Solution Approach 1:
The sensor structure enables self-powered operation through the built-in potential of the heterojunction. The graphene-light absorbing layer interface generates sufficient photocurrent under light irradiation to drive the detection process without external power supply, allowing indefinite usage time as long as light is available
Solution Approach 2:
The detection mechanism utilizes periodic light irradiation to generate photocurrent pulses. By illuminating the light absorbing layer in periodic fashion, the sensor achieves continuous detection capability with zero average power consumption, extending operational duration indefinitely
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Enables efficient detection of chemical substances with minimized power consumption, extending device usage time and enhancing IoT applications by operating without a driving voltage, while utilizing an ultra-thin graphene structure for sensitivity and miniaturization.
Implementation Method 1
a photocurrent is generated as light of bandgap energy or more is irradiated to the light absorbing layer
Implementation Method 2
the Fermi energy level is changed by adsorbing or desorbing the chemical substance on the surface of the graphene
Data Source
AI summary
Disclosed are a zero-power detecting sensor of a chemical substance and a sensing method. As light is irradiated to the detecting sensor including a graphene, a light absorbing layer, and an electrode stacked, the chemical substance is detected without power.