Passive RFID Tire Pressure Sensor with RF Energy Harvesting
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Solution Overview
Problem
Current wireless sensors, particularly those used for tire pressure monitoring, require batteries and MEMS circuitry for direct sensing, which increases costs and complexity, and existing RFID systems face challenges in efficiently powering and calibrating pressure sensing circuits for accurate environmental condition monitoring.
Innovation Solution
The development of a pressure-based wireless sensor system that utilizes a passive RFID topology with a power harvesting circuit to convert RF signals into DC supply voltage, powering a pressure sensing circuit that adjusts its resonant frequency to accurately measure tire pressure, and includes a processing module to calibrate and communicate the data effectively.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If batteries and MEMS circuitry are used for direct sensing in wireless sensors, then sensing accuracy is improved, but device complexity and cost increase
Solution Approach 1:
The patent extracts the battery and complex MEMS circuitry from the wireless sensor system, replacing them with a passive RFID-based pressure sensing circuit that harvests power from RF signals. This removal of unnecessary components directly reduces device complexity while maintaining pressure sensing functionality through a simplified circuit architecture.
Solution Approach 2:
The wireless sensor system provides its own power through RF energy harvesting, eliminating the need for external batteries. The pressure sensing circuit automatically calibrates itself by adjusting resonant frequency to match the RFID reader's carrier frequency, enabling self-service operation without complex power management or manual calibration procedures.
2Measurement precision
If batteries and MEMS circuitry are used for direct sensing in wireless sensors, then sensing accuracy is improved, but manufacturing cost increases
Solution Approach 1:
The patent replaces expensive, long-lasting batteries and complex MEMS circuitry with a simpler, passive RFID-based pressure sensing circuit that can be manufactured at lower cost. The simplified circuit architecture using standard RFID components and passive elements enables more cost-effective mass production while maintaining adequate sensing functionality for tire pressure monitoring applications.
Solution Approach 2:
By removing batteries and complex MEMS circuitry from the design, the patent eliminates expensive components and assembly steps, directly reducing manufacturing cost. The extracted simplified circuit uses fewer components that can be manufactured using more economical processes.
3Ease of operation
If existing RFID systems are used for pressure sensing, then wireless communication is achieved, but power efficiency and calibration accuracy deteriorate
Solution Approach 1:
The patent implements dynamic resonant frequency adjustment in the pressure sensing circuit, allowing it to automatically track and match the RFID reader's carrier frequency. This dynamic calibration improves measurement accuracy by adapting to frequency variations, while the RF energy harvesting provides efficient power management that enhances overall system reliability.
Solution Approach 2:
The system incorporates feedback mechanisms where the pressure sensing circuit monitors the RFID communication signals and adjusts its resonant frequency accordingly. This feedback loop ensures accurate calibration by continuously adapting to the operational environment, improving both power efficiency through optimized RF harvesting and calibration accuracy through real-time frequency matching.
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
This solution enables accurate, cost-effective, and efficient tire pressure monitoring by eliminating the need for batteries and simplifying the sensor design, while improving the accuracy and reliability of environmental condition data collection through efficient power management and calibration.
Implementation Method 1
a power harvesting circuit to convert RF signals into DC supply voltage
Implementation Method 2
the pressure sensing circuit measures pressure within its respective tire
Implementation Method 3
adjusts its resonant frequency to accurately measure tire pressure
Data Source
AI summary
A radio frequency identification (RFID) tag includes an antenna, an analog front end, a processing circuit, and memory. The analog front end includes a power circuit, a tuning circuit, a transmitter, and a receiver. The power circuit is operably coupled to convert a radio frequency (RF) signal into a power supply voltage. The tuning circuit, when enabled, adjusts an RF characteristic of the analog front end to tune power harvesting from the RF signal. The transmitter is operably coupled to transmit a response signal to the RFID reader via the antenna. The receiver is operably coupled to receive a command signal from the RFID reader, wherein the command signal is contained within a portion of the RF signal. The processing circuit is operable to interpret the command signal and generate the response signal.