RFID Capacitance Sensor Tag for Accurate Liquid Level Detection
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Solution Overview
Problem
Existing liquid level detection systems face challenges in accuracy, cost-effectiveness, and scalability, particularly in industries like hospitality and agriculture, due to human error, complex electronics, and limited penetration depth of conventional sensors.
Innovation Solution
A capacitance-based RFID sensor tag system with a capacitance sensor, chip, and RFID inlay, encapsulated in a BPA-free material, that operates battery-free and communicates via NFC, BLE, 5G, and Wi-Fi for accurate liquid level detection and inventory management.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional visual inspection methods are used for liquid level detection, then the system is simple and cost-effective, but accuracy is poor and prone to human error
Solution Approach 1:
The patent replaces manual visual inspection with an automated capacitance-based sensing system. The RFID sensor tag uses electrical field interactions to detect liquid levels, eliminating human error and providing precise, objective measurements without requiring complex mechanical or electronic assemblies.
Solution Approach 2:
The RFID sensor tag is a passive device that derives power from the RFID reader's electromagnetic field. It requires no internal battery or active power source, automatically detecting liquid levels through capacitance changes and communicating results wirelessly when interrogated, thereby serving itself without additional power infrastructure.
2Measurement precision
If complex electronic systems are used for liquid level detection, then measurement precision improves, but cost-effectiveness deteriorates and ease of operation worsens
Solution Approach 1:
The patent combines the RFID communication functionality with the capacitance sensing into a single integrated sensor tag. This merger allows the system to perform both wireless communication and precise liquid level detection using one compact component, reducing operational complexity while maintaining measurement accuracy.
Solution Approach 2:
The RFID sensor tag serves multiple functions: it acts as both a wireless communication device and a precision capacitance sensor. This multi-functionality eliminates the need for separate systems, making the technology easier to adopt and operate while delivering accurate liquid level measurements.
3Reliability
If conventional soil moisture sensors are used, then the system is simple to implement, but penetration depth is limited and reliability deteriorates
Solution Approach 1:
The patent replaces conventional electrical soil moisture sensors with a passive RFID-based capacitance sensing system. This substitution eliminates the need for active electronics and batteries in the field, improving long-term reliability by removing failure points while maintaining simplicity through the passive nature of the RFID tag.
4Duration of action of moving object
If battery-powered sensors are used, then duration of action improves, but use of energy increases and device complexity worsens
Solution Approach 1:
The RFID sensor tag is completely passive, deriving all necessary power from the electromagnetic field generated by the RFID reader during interrogation. This self-service approach eliminates batteries and internal power sources, achieving unlimited operational duration without energy consumption from the sensor itself, while reducing device complexity by removing power management components.
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
Provides accurate, cost-effective, and scalable liquid level detection across various applications, enabling real-time inventory management and soil moisture monitoring with redundant communication pathways for enhanced reliability.
Implementation Method 1
The capacitance sensor may be configured to detect changes in capacitance as a liquid level in the container varies
Implementation Method 2
The RFID inlay may be configured to transmit data processed by the chip to an external reader device
Data Source
AI summary
A liquid level detection system may comprise a sensor tag insertable into a container. The sensor tag may include a capacitance sensor, a chip, and an RFID inlay encapsulated within a rigid material. The sensor tag may be provided in different lengths with unique identifiers such as colors, numbers, or symbols. The sensor tag may include a weighting element at its bottom portion and RFID components positioned near the top. Power may be derived from the RFID antenna or from an internal battery. The system may function by measuring changes in capacitance as liquid levels vary, with the chip processing the data and the RFID inlay transmitting to external readers. The system may be adapted for various applications including beverage inventory management and agricultural soil monitoring, providing accurate, automated monitoring capabilities for liquid levels or soil moisture conditions.