Wearable Metasurface Segmented Ground Plane for Passive Authentication
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Solution Overview
Problem
Existing wearable devices for activity tracking and health monitoring, such as rings and wristwatches, are bulky, costly, and require frequent charging due to their electrical components and small batteries, limiting their convenience and practicality.
Innovation Solution
A passive wearable metasurface with a segmented ground plane that activates or deactivates based on skin conductivity, using a metasurface with unit cells that resonate when worn, reflecting signals without power, and an iterative design process to optimize electromagnetic responses.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If traditional electrical components (battery, sensors, circuits, antennas) are used in wearable devices, then communication functionality is achieved, but device size, cost, and complexity increase
Solution Approach 1:
The patent extracts and removes the battery, sensors, circuits, and antennas from the wearable device, retaining only the metasurface component. This extraction eliminates the complexity and size issues while maintaining communication functionality through the passive metasurface that interacts with electromagnetic fields from external transceivers.
Solution Approach 2:
The patent replaces the traditional mechanical and electrical system (battery-powered electronics) with an electromagnetic field-based system. The metasurface manipulates electromagnetic waves to enable communication without requiring powered electronic components, thus reducing device complexity while maintaining reliability.
2Weight of moving object
If small battery size is used in wearable devices, then device portability is improved, but charging frequency increases
Solution Approach 1:
The patent completely removes the battery from the wearable device, eliminating the need for charging operations. The device operates passively using the metasurface to interact with electromagnetic fields, thus abolishing the time loss associated with frequent charging while maintaining minimal weight.
3Use of energy by moving object
If passive metasurface with segmented ground plane is used, then power consumption is reduced to zero, but electromagnetic response optimization becomes more complex
Solution Approach 1:
The patent applies segmentation to the ground plane, dividing it into multiple separate segments rather than using a continuous ground plane. This segmentation enables the metasurface to achieve distinct electromagnetic responses in different states (worn vs. not worn) while maintaining zero power consumption, as the segmentation creates state-dependent electrical connectivity without requiring active control.
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 a compact, cost-effective, and power-efficient wearable device that seamlessly interacts with computing devices, enhancing personal security and authentication through distinct electromagnetic signatures.
Implementation Method 1
unit cells that resonate when worn, reflecting signals without power
Implementation Method 2
reflecting signals without power
Implementation Method 3
skin conductivity electrically connecting the separated segments
Data Source
AI summary
The technology described herein is directed towards designing and deploying a wearable device that includes a passive metasurface of unit cells with a segmented ground plane of electrically separated segments. When the wearable device is worn, e.g., as a ring or wristband that contacts the wearer's skin, the wearer's skin conductivity electrically connects the separated segments to provide a ground plane. With a complete ground plane, the metasurface's unit cells resonate when exposed to a transmitted signal and reflect a distinct signature corresponding to a physical radiation pattern of signals reflected by the activated metasurface. When not worn, the metasurface is deactivated because of the electrically disconnected ground plane segments. Discontinuity parameters of size, position, and quantity of ground discontinuities are iteratively varied during modeling of a metasurface to determine the design with the largest difference in performance characteristics for when the device is worn versus not worn.