Capacitive Sensor Array Sharing Single Channel
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Solution Overview
Problem
Wearable motion capture systems based on soft electronic circuits face challenges with signal transfer and processing due to the need for additional components and rigid connections, which increase the circuit board size and compromise the soft and unobtrusive nature of the sensors.
Innovation Solution
A sensing apparatus utilizing a set of capacitive sensors connected over a single physical channel, with each sensor having electrodes separated by a dielectric to vary capacitance with deformation, and a solution module to determine capacitance by equating reactance measured at terminals to an analytical model, allowing for impedance measurement and resistance calculation using an excitation signal with multiple frequency components.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If every sensor is connected to a separate physical channel, then measurement precision is improved, but device complexity increases due to significant circuit board footprint and larger area required
Solution Approach 1:
Multiple capacitive sensors are connected in parallel to share a single physical channel (two terminals), merging multiple measurement functions into one communication interface. This eliminates the need for separate channels for each sensor, significantly reducing circuit board footprint while maintaining individual sensor measurement capability through parallel connection topology
Solution Approach 2:
The single physical channel serves multiple functions by sequentially or simultaneously measuring capacitance of multiple sensors through parallel connection. The shared channel acts as a universal interface that can identify and measure each sensor's capacitance value, enabling one channel to perform what traditionally required multiple dedicated channels
2Reliability
If electrical connections are established through separate non-stretchable wires, then reliability of electrical connection is improved, but device complexity increases due to considerable number of rigid components added to soft sensing device
Solution Approach 1:
Multiple wire connections are merged into a single two-terminal interface. Instead of having separate wires for each sensor, all sensors connect in parallel to the same two terminals, reducing the number of rigid wire components from multiple individual connections to just one shared connection path
Solution Approach 2:
The patent employs soft, stretchable conductive traces printed directly on flexible substrates instead of rigid non-stretchable wires. These thin film conductors maintain electrical connectivity while accommodating the soft and deformable nature of the sensing device, eliminating the need for rigid wire components
3Ease of operation
If separate physical channels are used for each sensor, then ease of operation is improved, but device complexity increases due to significant circuit board footprint
Solution Approach 1:
Multiple signal transfer paths are merged into a single shared physical channel. The parallel-connected sensors all communicate through the same two terminals, simplifying the overall signal transfer architecture while reducing circuit board area requirements compared to having separate dedicated channels for each sensor
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
Enables efficient sensing of deformation in soft electronic circuits with reduced circuit board size and minimal rigid components, maintaining the soft and unobtrusive nature of the sensors while accurately measuring capacitance and resistance.
Implementation Method 1
each capacitive sensor having electrodes separated by a dielectric to provide a capacitance which is able to vary with deformation to provide sensing
Implementation Method 2
a solution module operable to determine the capacitance of each capacitive sensor by finding solutions for a vector function equating reactance measured at the two terminals to an analytical model for impedance and/or reactance of the circuit
Data Source
AI summary
In one aspect the invention provides a sensing apparatus comprising a set of N capacitive sensors connected over a single physical channel provided by two terminals, the apparatus comprising: a sensing array having a first capacitive sensor and N−1 parallel capacitive sensors each connected in parallel with first capacitive sensor, each capacitive sensor having electrodes separated by a dielectric to provide a capacitance which is able to vary with deformation to provide sensing, the array having a set of N−1 resistances each being in series with a respective one of the N−1 parallel capacitive sensors; a solution module operable to determine the capacitance of each capacitive sensor by finding solutions for a vector function equating reactance measured at the two terminals to an analytical model for impedance and/or reactance of the circuit seen at the two terminals, wherein the analytical model comprises N capacitances, each connected in parallel with each other, and comprises N series resistances each connected in series with a respective capacitance.