Miniaturized Electrochemical Sensor High-Aspect-Ratio Passages
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Solution Overview
Problem
Conventional electrochemical sensors for detecting nitric oxide in exhaled breath lack fast response times and high sensitivity, requiring complex flow handling and are not suitable for handheld devices due to their size and manufacturing costs.
Innovation Solution
A miniaturized electrochemical sensor with a structure featuring passages with a high aspect ratio, covered by a working electrode and an ionomer layer, which increases the sensing area and response time, and is manufactured using silicon microfabrication and batch processing to reduce costs and enhance sensitivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If conventional electrochemical sensors are used to detect nitric oxide, then detection capability is provided, but response time is long (60-100 seconds) and device size is large
Solution Approach 1:
The patent transitions from a planar electrode geometry to a three-dimensional structure with high-aspect-ratio passages (height/width ratio of at least 2). The working electrode lines the walls of these passages, creating a vertical sensing architecture that increases surface area without increasing the device footprint. This dimensional change enables faster response times while maintaining compact device size suitable for handheld applications.
Solution Approach 2:
The sensor incorporates a structure with an array of passages forming a porous-like architecture. This multi-channeled structure provides extensive surface area for the working electrode while maintaining a small overall device volume. The passages allow rapid gas diffusion to the electrode surface, contributing to the improved response time of 6 seconds or less.
2Measurement precision
If conventional electrochemical sensors are used, then detection is possible, but sensitivity is insufficient for low concentration eNO detection
Solution Approach 1:
By transitioning from a two-dimensional planar electrode to a three-dimensional structure with high-aspect-ratio passages, the sensor achieves a dramatically increased surface area within a compact footprint. This dimensional transformation provides sufficient sensing area for high sensitivity detection without requiring a complex array of separate sensor elements, thus maintaining manufacturing simplicity.
Solution Approach 2:
The sensor employs a composite structure combining a solid-state electrochemical sensor with an ionomer coating on the working electrode. This composite approach enhances sensitivity for detecting low concentrations of nitric oxide while maintaining a relatively simple single-unit structure that can be manufactured using standard techniques.
3Volume of moving object
If sensor size is reduced for handheld devices, then portability is improved, but sensing area decreases and sensitivity is reduced
Solution Approach 1:
The patent successfully decouples device volume from sensing area by implementing a vertical architecture with high-aspect-ratio passages. The working electrode coats the internal walls of these narrow, tall passages, providing extensive surface area within a small footprint. This enables the sensor to maintain high sensitivity for ppb-level eNO detection while being compact enough for handheld devices.
4Speed
If fast response time is achieved, then measurement speed is improved, but sensor complexity increases
Solution Approach 1:
The high-aspect-ratio passage structure provides a straightforward geometric solution for achieving fast response times. The narrow passage dimensions create short diffusion paths for gas molecules to reach the electrode surface, enabling response times of 6 seconds or less. This geometric approach avoids the need for complex flow control systems or signal processing mechanisms.
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
The sensor achieves high sensitivity and fast response times, enabling effective detection of nitric oxide levels in exhaled breath, with a detection limit of 0.3 ppb and a response time of 6 seconds, while being compact and cost-efficient for handheld devices.
Implementation Method 1
a layer of an ionomer covers at least part of the working electrode along the walls of the structure. The layer of ionomer is in ion conducting contact with the electrodes
Implementation Method 2
A miniaturised electrochemical sensor for detection of a component in a gas
Data Source
Figure 1~2
Figure 3a~3d
AI summary
A miniaturised electrochemical sensor for detection of a component in a gas is provided. The sensor comprises a reference electrode, a counter electrode and a structure comprising a plurality of passages delineated by walls extending along the passages. The passages have an aspect ratio of at least 2. A working electrode covers the walls of the structure and a layer of an ionomer covers at least part of the working electrode along the walls of the structure. The layer of ionomer is in ion conducting contact with the electrodes. The disclosure further relates to a method of fabricating a miniaturised electrochemical sensor and to a device for measuring content of NO in exhaled breath comprising such a miniaturised electrochemical sensor.