The invention concerns a wireless and passive transponder dedicated to vibration and pressure sensing, where the sensitive component only consists of transmission lines. In particular, the sensing element is a 3-dimentional directional coupler. This makes the sensor low-cost, lightweigth and suitable for green manufacturing technologies.
The transponder, connected to the device (“device under test” or DUT), is interrogated by a reader with a sinusoidal signal at frequency f0 (or carrier frequency). The DUT can be a vibrating platform, such as an aircraft or industrial machinery. If there are no vibrations, the transponder reflects the signal, without changing its spectrum. If the DUT is subjected to vibrations, however, the sensor uses the displacement caused by the vibrations to modulate the carrier frequency. In this way, the amplitude and frequency of the vibration are encoded in the sidebands of the reflected signal, and this information can be retrieved by the reader.
Patent Status
PENDING
Priority Number
102021000014681
Priority Date
04/06/2021
License
ITALY
Market
The sensor can be applied for structural health monitoring of buildings and more generally for condition monitoring applications. It can find applications in industry, transportations, domotics, logistics and infrastructures. The proposed technology has the potential to reduce the cost of the sensors by one order of magnitude, thereby increasing the number of sensorws that can be used for each application and increasing the spatial resolution of the acquired information. Therefore, it has a very broad potential market.
Problem
Mechanical structures deteriorates with time, with serious consequences for safety and production. Therefore, we need to identify problems tempestively to reduce risks. Hidden cracks and wear can be easily identified by analyzing the vibrations of the body and the pressure between different mechanical parts of a machine, which is why vibration and pressure sensors are needed in industrial machines, aeroplanes, buildings and infrastructures.
Current Technology Limits
Current vibration and pressure sensors are active or a connected to the grid. This is very limiting, especially for sensors that must be placed on mobile structures. Active wireless sensors require external energy sources, which are usually provided by batteries.
However, periodic battery replacements can be impractical if the sensors are placed on machinaries or in remote area.s, while energy harvesting approaches for battery recharging are not always applicable. Additionally, vibration sensors can require the use of piezoelectric materials that are expensive and generaly polluting for the environment (such as PZT).
Killer Application
The main application for the proposed sensor is condition monitoring in industrial condition monitoring, where the sensor can be used to monitor compressive forces and vibrations wirelessly without requiring any active circuitry.
Additional areas are:
Our Technology and Solution
The proposed sensor is based on a 3-dimentional directional coupler. Compressive forces can bring the lines nearer, thereby increasing the coupling coefficient. Therefore, the power ratio between the direct and the coupled port is a function of the applied force, while periodic solicitations (i.e., vibrations) cause the presence of sidebands in the acquired spectrum. The information can be transmitted wirelessly using harmonic backscattering, and the sensing information can be retrieved from the second harmonic backscattered from the direct and coupled ports of the directional coupler.
Such sensor can be realized using low-cost manufacturing technologies, such as 3D printing.
Vantaggi
The proposed approach allows us to develop low-cost and lightweigth sensors, which do not require periodic maintenance and battery replacements. The absence of batteries reduces the weigth, and environmental impact of the sensor as well, and allow for the sensor use in harsh environments.
Roadmap
First of all, a complete prototype and its related reader should be developed and tested in a wireless scenario. The most suitable technology should be identified to manufacture 3D structures with metal patterns. Finally, the sensor should be tested in relevant environments.
TRL
Team
