Single-Chip UHF RFID Strain Sensor for Low-Power Long-Range Reading
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Solution Overview
Problem
Passive RFID tags operating in the UHF band face limitations such as short reading range, high energy consumption, and large size due to the use of external sensors with digital interfaces, which consume significant power and extend reading time.
Innovation Solution
A single-chip passive RFID tag design integrating a transducer and sub-circuits for measurement and transmission, utilizing orthogonal strain-sensitive transistors and a control device to harvest energy during an energy recovery phase, acquire and digitize measurements during the same phase, and transmit during a communication phase, reducing power consumption and increasing reading distance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If an external sensor with digital interface is used, then measurement capability is improved, but energy consumption increases and reading time extends
Solution Approach 1:
The patent integrates the sensor directly into the RFID tag circuit, merging the measurement function with the communication function. This eliminates the need for separate external sensors with digital interfaces, thereby reducing energy consumption while maintaining measurement capability through the integrated transducer.
Solution Approach 2:
The patent replaces mechanical/discrete sensor interfaces with an integrated electronic transducer that directly outputs signals compatible with the RFID tag's communication protocol. This substitution eliminates the need for complex digital interfaces and reduces overall energy consumption.
2Measurement precision
If an external sensor with digital interface is used, then measurement capability is improved, but device size increases
Solution Approach 1:
The patent combines the sensor and RFID tag into a single integrated unit, eliminating the need for separate external sensors and their associated digital interface components. This integration significantly reduces the overall device size while maintaining full measurement functionality.
3Weight of moving object
If passive RFID tag is used, then weight and cost are reduced, but reading range is limited
Solution Approach 1:
The patent performs stress measurement and signal acquisition during the energy recovery phase of the RFID protocol, before the communication phase begins. This preliminary action allows the tag to process and prepare data in advance, enabling more efficient use of harvested energy and potentially extending reading range through optimized communication timing.
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 solution enables rapid stress measurement with reduced energy consumption, allowing for a reading distance up to 5 meters and quick response times, while maintaining a compact size and compliance with the EPC UHF Gen2 Air Interface protocol.
Implementation Method 1
a transducer (51) for measuring a stress
Implementation Method 2
These tags use the energy contained in the reader's signal carrier to send a modulated version of the reader's signal back to the RFID reader
Data Source
Figure 1~2
Figure 3
Figure 4
AI summary
The invention relates to a circuit (1) for a passive radio-frequency identification tag operating in a UHF band, configured for radio communication with a reader that emits a read signal. The circuit is produced as a single chip, comprising one or more transducers for measuring a strain, a first sub-circuit (43) configured to acquire the measurement from the transducer and a second sub-circuit (2, 3) configured for radio transmission of the acquired measurement to the reader. The invention also relates to a system and a method.