Passive Sensor Tag System RF Energy Harvesting
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Solution Overview
Problem
Current remote sensors require a power source, increasing their size and maintenance needs, limiting their placement in desired locations, and often necessitating accessible locations for battery replacement.
Innovation Solution
A passive sensor tag system with a sensor element that alters its fundamental electrical resonance frequency in response to environmental changes, allowing a passive electronic sensor tag to be interrogated by an external readout without a power source, enabling reduced form factor and maintenance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a power source is included in the sensor package, then the sensor can function and transmit data, but the size and form factor of the sensor package increases
Solution Approach 1:
The patent extracts the power source from the sensor package, creating a passive sensor that derives power from the RF interrogation signal itself. This eliminates the battery or power supply component, directly reducing the sensor package volume while maintaining functionality through electromagnetic energy harvesting from the readout signal.
Solution Approach 2:
The patent replaces the mechanical/power-based energy supply system with an electromagnetic field-based energy harvesting system. The passive sensor harvests energy from the RF electromagnetic field generated by the external readout, substituting the need for physical batteries or power sources with wireless electromagnetic energy transfer.
2Reliability
If a power source is included in the sensor package, then the sensor can function, but maintenance requirements increase due to power source replacement
Solution Approach 1:
By extracting and eliminating the power source component entirely, the patent removes the maintenance burden associated with battery replacement or power supply servicing. The passive sensor design requires no user intervention for power management, significantly improving ease of operation and reducing maintenance requirements.
Solution Approach 2:
The passive sensor serves itself by harvesting energy from the interrogation signal, eliminating the need for external power management, battery replacement, or maintenance. The sensor automatically derives the energy it needs from the readout process itself, making it self-sufficient and maintenance-free.
3Reliability
If a power source is included in the sensor package, then the sensor can transmit data, but the sensor must be placed in accessible locations for battery replacement
Solution Approach 1:
By removing the power source requirement, the patent enables sensor placement in previously inaccessible locations such as inside sealed containers, embedded in structures, or in hazardous environments where battery replacement would be difficult or impossible. The passive design allows deployment in locations that were previously inaccessible.
Solution Approach 2:
The self-powered nature of the passive sensor through RF energy harvesting enables deployment in remote, inaccessible, or hazardous locations without concern for power source replacement. The sensor adapts to any location where the external readout can transmit the interrogation signal, dramatically increasing placement flexibility and versatility.
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 sensors to be placed in various locations with reduced size and power requirements, allowing for continuous monitoring of environmental variables without maintenance, as the external readout determines changes in resonance frequency to correlate with environmental data.
Implementation Method 1
A change in the local environment causes a reactionary change in the sensor element, which alters a fundamental electrical resonance frequency characteristic of the sensor tag
Implementation Method 2
An external readout includes an external readout circuit that generates a signal at a fixed voltage output that is transmitted through an output antenna to the passive electronic sensor tag
Data Source
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AI summary
A passive sensor tag system including a passive electronic sensor tag and an external readout. The passive electronic sensor tag including a sensor element configured to sense data in a local environment and to cause a shift in a fundamental electrical resonance frequency characteristic of a sensor circuit based on the sensed data. The external readout including an external readout circuit that is configured to generate a signal having a frequency and a voltage and to transmit the signal through an output antenna. The transmitted signal coupling the sensor circuit and the external readout circuit. The external readout determining a fundamental electrical resonance frequency characteristic of the sensor circuit based on the impedance of the coupled sensor circuit and external readout circuit. The external readout determining the sensed data based the fundamental electrical resonance frequency characteristic of the sensor circuit.