Multilayer Titanium Nitride Electrode for Low-Frequency Impedance
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Solution Overview
Problem
Current impedance spectroscopy systems for biological media face high costs and limitations due to the use of expensive precious metal electrodes, which have unfavorable impedance properties and require complex cleaning and sterilization, making them unsuitable for automatable in vitro systems.
Innovation Solution
A multilayer titanium electrode with a titanium-rich titanium nitride intermediate layer and a titanium-poor titanium nitride cover layer is applied to thermoplastic substrates using physical vapor deposition, offering improved electrical properties and chemical stability for impedance measurements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If precious metal electrodes (gold or platinum) are used for impedance spectroscopy, then chemical stability and reliable connection are improved, but acquisition costs and operating costs increase significantly
Solution Approach 1:
The invention changes the material composition parameters by using titanium and titanium nitride instead of precious metals, and optimizes the layer structure with specific thickness ratios (Ti carrier layer: 1-5 µm, TiN intermediate layer: 0.5-2 µm, TiN cover layer: 0.1-1 µm) to achieve the desired electrical and chemical properties at lower cost
Solution Approach 2:
The invention applies a composite multilayer structure consisting of titanium carrier layer, titanium nitride intermediate layer, and titanium nitride cover layer. This composite structure combines the chemical stability of titanium with the improved impedance properties of titanium nitride, achieving performance comparable to precious metals without the high cost
2Duration of action of stationary object
If precious metal electrodes are used for impedance spectroscopy, then long-term use is possible, but cleaning and sterilization complexity increase
Solution Approach 1:
The invention enables a disposable electrode approach where titanium-based electrodes are applied to single-use cell culture plates. The electrodes maintain reliability for their intended use period and are then discarded with the plate, eliminating the need for complex cleaning and sterilization procedures while maintaining chemical stability during the measurement period
Solution Approach 2:
The multilayer structure provides different functional properties at different layers: the titanium carrier layer provides mechanical strength and chemical stability, the TiN intermediate layer provides adhesion and corrosion resistance, and the TiN cover layer provides optimized electrical properties. This local differentiation allows the electrode to function effectively without requiring post-use maintenance
3Reliability
If precious metal electrodes are used for impedance measurement, then connection reliability is improved, but impedance properties (high resistance and high phase shift) worsen
Solution Approach 1:
The invention changes the electrical parameters by using titanium nitride, which has superior impedance properties compared to precious metals. The specific stoichiometry and layer thickness are optimized to minimize resistance and phase shift, improving measurement sensitivity while maintaining connection reliability through the titanium-based structure
4Ease of manufacture
If titanium electrode with titanium nitride layers is applied to low-melting thermoplastic substrates, then cost efficiency and ease of manufacture are improved, but thermal stress during deposition may damage the substrate
Solution Approach 1:
The invention applies preliminary protective measures by using a titanium carrier layer that acts as a buffer between the deposition process and the thermoplastic substrate. This intermediate layer protects the substrate from thermal stress during the sputtering process while allowing the titanium nitride layers to be deposited successfully
Solution Approach 2:
The multilayer structure provides localized thermal management where the titanium carrier layer absorbs and distributes thermal energy during deposition, protecting the thermoplastic substrate from damage while allowing the titanium nitride layers to form with proper crystalline structure and electrical properties
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 titanium electrode provides superior sensitivity and impedance behavior, especially in the low-frequency range, enabling cost-effective and continuous impedance measurements in biological media without the need for complex cleaning or sterilization, suitable for single-use cell culture plates and automatable systems.
Implementation Method 1
A first titanium carrier layer of elemental titanium, a titanium-rich titanium nitride intermediate layer and a titanium-poor titanium nitride cover layer, which rests on the titanium-rich titanium nitride intermediate layer, are formed on a titanium carrier layer
Data Source
AI summary
A multilayer electrode on a substrate (10) comprising titanium (20) and titanium-rich titanium nitride (30) and titanium-poor titanium nitride (40), particularly suitable for the application to thermoplastic substrates, in particular for the purpose of the impedance measurement in aqueous biological media, and method for the production thereof.