CMOS Microneedle Structures for Neuron Sensing
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Solution Overview
Problem
Current micro-electrode arrays and microneedle technologies face challenges in efficiently measuring and stimulating small cells like mammalian neurons due to limited spacing and functionality, with existing microneedles being too large and lacking integration with sensing and actuation capabilities.
Innovation Solution
The development of CMOS-compatible electronic devices featuring microneedles with channels surrounded by insulating layers, allowing for integration with integrated circuitry and microfluidic channels, enabling both sensing and actuation functions, and capable of being used with small cells like neurons.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If traditional micro-electrode arrays are used, then electrode fabrication is simple, but the spacing between electrodes is large (minimum 100 μm) and cannot achieve required small spacings (e.g., 6 μm)
Solution Approach 1:
The patent transitions from planar 2D electrode arrays to 3D microneedle structures protruding from the substrate surface. This dimensional change enables much smaller spacing between electrodes (down to 6 μm) while maintaining manufacturability through standard CMOS processes, as the vertical protrusion allows independent positioning without increasing lateral fabrication complexity
Solution Approach 2:
The microneedle structure is segmented into distinct functional zones: the substrate layer, the microneedle protrusions, and the top electrode layer. This segmentation allows each layer to be optimized independently using standard CMOS fabrication steps, achieving high precision spacing without overwhelming process complexity
2Adaptability or versatility
If microneedles are made large for transdermal drug delivery, then drug delivery capability is achieved, but the needles cannot be used for in-vitro experiments on small cells
Solution Approach 1:
The patent enables continuous adjustment of microneedle dimensions (height, diameter, spacing) through CMOS fabrication parameters. This allows optimization for different applications: smaller needles (few micrometers) for in-vitro neuron experiments, or larger needles for in-vivo transdermal delivery, all using the same fabrication platform
Solution Approach 2:
The CMOS-compatible microneedle platform is designed to be universally applicable across multiple domains. The same fabrication process can produce needles suited for in-vitro electrophysiology, in-vivo drug delivery, or combined functions, making the system adaptable rather than application-specific
3Adaptability or versatility
If existing microneedle fabrication methods are used, then microneedle structures can be created, but extra functionality cannot be provided on top of the needles
Solution Approach 1:
The patent merges microneedle fabrication with standard CMOS electronic device fabrication into a unified process. This allows multiple functionalities (electrodes, interconnects, passive components) to be integrated on the same substrate without requiring separate fabrication steps, maintaining ease of manufacture while enabling functional complexity
Solution Approach 2:
The microneedle structure serves multiple functions simultaneously: mechanical penetration, electrical stimulation, and signal recording. The integration of electronic circuitry with the microneedles enables combined sensing and actuation capabilities, providing extra functionality without complicating the manufacturing approach
4Reliability
If one microneedle is attached to electronic circuitry using a probe arm, then electrical connection is achieved, but assembly is difficult and fixing is not straightforward
Solution Approach 1:
The patent merges the microneedle and electronic circuitry into a single integrated device fabricated using the same CMOS process. This eliminates the need for separate probe arm assembly and fixing operations, as the electrical connections are formed during the standard fabrication process rather than through post-fabrication assembly
Solution Approach 2:
The patent eliminates the probe arm intermediary component by directly integrating the microneedle with the electronic circuitry. The microneedle itself becomes the electrical conductor, removing the need for additional assembly steps and fixing mechanisms that complicate manufacturing
Data Source
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AI summary
The present application describes an electronic device for sensing and/or actuating, comprising a substrate (1) containing CMOS electronics (2) and at least one microneedle (10), each of the microneedles (10) comprising at least one channel (7,8) surrounded by an insulating layer (6). Also described is a method for making such an electronic device. The device is especially intended for monitoring electrical activity, eg. action potentials, in small networks of neurons.