3D FET Probe Sensing Cellular Activity
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Solution Overview
Problem
Existing biomedical sensors face limitations such as pharmacological side effects, phototoxicity, and mechanical insertion challenges due to size constraints, and lack in situ signal amplification and addressable-array formation, particularly for three-dimensional (3-D) configurations.
Innovation Solution
Development of three-dimensional biomedical probe devices with a planar substrate, featuring a probe structure with a tip dimension between 5 nanometers and 5 microns, capable of AC, DC, or transient current, charge, or voltage sensing, and configured as a field-effect transistor (FET) with a self-contained reference-electrode capability, enabling wireless communication and minimally invasive cellular penetration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If voltage-sensitive dyes are used for sensing, then optical detection is enabled, but pharmacological side effects and phototoxicity occur
Solution Approach 1:
The patent replaces optical detection methods (voltage-sensitive dyes) with direct electrical sensing using FETs. The FET gate electrode directly detects voltage changes and ionic flux in cells through electrical field interactions, eliminating the need for optical dyes and their associated pharmacological side effects and phototoxicity.
Solution Approach 2:
The FET gate electrode acts as an intermediary between the cell and the detection system. It detects cellular electrical signals and ionic flux without requiring direct mechanical penetration or optical interaction, serving as a non-invasive mediator that translates biological signals into measurable electrical signals.
2Reliability
If microelectrode probes are used for mechanical insertion into tissue and cells, then direct ionic and electrical contacting is achieved, but size constraints are imposed due to current-drawing impedance problems
Solution Approach 1:
The patent replaces mechanical insertion and direct ionic contacting with electrical field-based detection. The FET gate electrode detects cellular signals through electrical field interactions without requiring mechanical penetration into cells, thereby eliminating size constraints imposed by current-drawing impedance problems.
Solution Approach 2:
The FET gate electrode serves as an intermediary that detects cellular electrical signals without requiring direct physical contact. This eliminates the need for mechanically inserted microelectrodes and their associated size constraints.
3Measurement precision
If FET probes with complete FET structure are used, then sensing capability is improved, but design of 3D probes and minimally invasive insertion becomes a substantial challenge
Solution Approach 1:
The patent extracts only the essential sensing function from the complete FET structure. Instead of incorporating the entire FET (gate, source, drain, channel), it uses a simplified FET probe with just the gate electrode and minimal necessary components, reducing design complexity while maintaining sensing capability.
Solution Approach 2:
The patent segments the FET structure into essential and non-essential components. It retains only the gate electrode for sensing and omits the source, drain, and channel regions, creating a simplified probe structure that is easier to design and manufacture while maintaining sensing functionality.
4Ease of manufacture
If planar FET probes are used, then manufacturing is simplified, but 3D configuration and minimally invasive insertion into cells is not achieved
Solution Approach 1:
The patent transitions from planar (2D) FET probes to three-dimensional (3D) FET probes by extending the gate electrode structure vertically. This dimensional change enables minimally invasive insertion into cells and tissues while maintaining the electrical field-based sensing capability of the FET.
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 3-D probe devices allow for spatially localized, electrically addressable sensing without mechanical motion, minimizing cellular lysis and enabling precise monitoring of physiological activities across multiple cell regions, overcoming previous size and functionality constraints.
Implementation Method 1
FETs can detect by monitoring the gate (G) electrode current, but they also have the basic advantage that they can sense by detecting gate charge variations without the need for particle current exchange with media such as cellular medium or body fluids; thus, interfacial impedance effects can be minimized.
Implementation Method 2
The probe structure forms a well or has a base and a portion essentially perpendicular to the base extending along a length to a tip and has a linear dimension at the tip of said probe structure of between 5 nanometers (nm) and 5 microns thereby defining an AC, DC, or transient current, charge, or voltage sensing probe.
Implementation Method 3
The FET gate electrodes can also be functionalized (e.g., coated by the purposeful chemical bonding of various molecules such as antibodies, antigens, or ligands) to probe for the presence of very specific bio-chemicals within a cell.
Data Source
AI summary
A three dimensional biomedical probe device is provided that includes a planar substrate. A probe structure is supported on the planar substrate. The probe structure has a base and a portion essentially perpendicular to the base extending along a length to a tip and has a linear dimension at the tip of said probe structure of between 5 nanometers (nm) and 5 microns thereby defining an AC, DC, or transient current, charge, or voltage sensing probe. In one variation, this probe is the electrical contact to the biomedical medium. In another variation, this probe is also the gate electrode of a field effect transistor (FET). An array of selectively electrically addressable such devices is also provided giving the ability to sample the physiological activity at many positions within cells, fluids and intercellular regions without the need for mechanical motion and inducing cellular lysis.