Flexible ISFET on Plastic Substrate for Shatter-Resistant Sensing
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Solution Overview
Problem
Conventional ion-sensitive field effect transistors (ISFETs) on silicon CMOS wafers are limited by small sensing array size, high manufacturing costs, and fragility, which restricts their use in applications requiring flexibility and durability, such as food and water-quality monitoring.
Innovation Solution
Development of flexible ISFETs using thin film transistor technology on durable substrates, allowing for larger sensing areas and reduced costs, with a flexible substrate attached to a rigid support and then removed, featuring a thin-film transistor with a source, drain, gate, and active channel layer, and a surface sensing layer in electronic communication with the gate.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional ISFETs are manufactured on silicon CMOS wafers, then manufacturing precision and reliability are improved, but device fragility and cost increase
Solution Approach 1:
The patent replaces rigid silicon CMOS substrates with flexible plastic substrates and uses thin-film transistor (TFT) technology to fabricate the ISFET devices. This transition enables the sensor to be flexible and shatter-resistant while maintaining sensing functionality, directly resolving the contradiction between reliability and fragility.
2Manufacturing precision
If ISFET sensing arrays are manufactured on silicon wafers, then manufacturing precision is improved, but sensing array area and productivity are limited
Solution Approach 1:
By transitioning from rigid silicon wafers to flexible plastic substrates, the patent enables the fabrication of large-area sensing arrays that are not constrained by the size of rigid substrates or photolithographic stepper field sizes. This allows sensing areas to exceed 1 cm² while maintaining fabrication precision through TFT processes.
3Reliability
If ISFETs are manufactured on silicon CMOS wafers, then device performance is improved, but manufacturing cost and device complexity increase
Solution Approach 1:
The patent changes the substrate material parameter from silicon to plastic and employs thin-film transistor fabrication techniques, which are more cost-effective for large-area production. This parameter change enables the manufacturing of large-area ISFET arrays at lower costs while maintaining sensor performance through careful selection of TFT process parameters.
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 flexible ISFETs provide a shatter-resistant, cost-effective solution with enhanced sensing capabilities, enabling larger sensing areas and easier integration with microfluidics for applications like drug delivery and health monitoring, while maintaining pH sensitivity and stability.
Implementation Method 1
The surface sensing layer is in electronic communication with the gate of the thin-film transistor, allowing detection of ion-selective properties
Data Source
AI summary
A flexible ion-selective field effect transistor (ISFET) and methods of making the same are disclosed. The methods may comprise: (a) attaching a flexible substrate to a rigid support with an adhesive; (b) forming an ion-selective field effect transistor structure on a surface of the flexible substrate; and (c) removing the flexible substrate from the rigid support after step (b).