Scientific innovation and technology continue to promote our development. The ultra-thin RFID force measurement “sticker” (called “ForceSticker“) developed by a team at the University of California, San Diego (UCSD) is one example. Not only can this innovative force-measuring sticker be used in medical and industrial situations, but it can also be used on the bottom of warehouse packages to measure their weight, functioning as a miniature scale.

forcesticker

ForceSticker was developed from the integration of two main components: a tiny capacitor just a few millimeters thick and about the size of a grain of rice, and a commercially available 900 MHz ultra-high frequency RFID IC tag. The researchers integrated the two components so that they could measure the applied force and wirelessly transmit the information to a standard RFID reader.

The emergence of this kind of sticker means that the research on RFID tags has gone a step further. If you are a customer who needs RFID tags for commercial purposes, please contact Newbega.

Table of Contents

What is ForceSticker?

The design of this force-measuring sticker was inspired by a keen observation of changes in capacitance. When an external force is applied, the polymer compresses, pulling the copper strips closer together, thereby increasing capacitance. With this design, researchers can evaluate the sensor’s switching capabilities based on an optimized capacitance range design derived from mathematical RF modeling and perform multiphysics simulations in COMSOL.

sticker

In the actual application of the ForceSticker, the researchers used two different 4×2 mm sensor implementations with different layers of Ecoflex polymer (a biodegradable platinum-catalyzed silicon-based polymer) and neoprene covering 0 to 6 N and 0 to 40 N ranges; the reading errors are 0.25 N and 1.6 N, respectively. Additionally, they stress-tested the ForceSticker over 10,000 times and found no significant error reduction.

This passive RFID tag uses backscatter for power and data transmission. It receives an incoming radio signal from an RFID reader, modifies the signal through electrical changes induced by a capacitor, and then reflects the modified signal back to the reader, which interprets and converts it into force. This approach directly inserts the analog RF phase shift generated by the sensor into the RFID tag’s wireless channel path, creating an analog-to-digital backscatter link.

Challenges faced by ForceSticker

In the process of achieving sensor integration, a key challenge is the design of the sensor interface. To enable sensor integration without losing signal fidelity, the researchers used a matched-impedance coplanar waveguide approach. Furthermore, in order to obtain this sensitivity tuning, the capacitor must have a properly designed “nominal value” at zero force. This is determined by various nonlinear equations that model this situation, taking into account the impedance and reflection coefficient of the transmission line.

rfid ic tag

When simulating the interface between capacitive sensors and digital identification RFID, the researchers did so by inserting the sensor between an antenna and an RFID IC in parallel with the two. However, the researchers note that there are two so-called “degenerate” solutions (meaning at least one fundamental variable is zero). One of the solutions assumes that all phase changes are reflected directly from the sensor and no signal reaches the RFID module. Another solution assumes that the sensor’s capacitive switching mode actually operates. Both solutions provide guidance for further optimization of the technology.

Conclusion

Overall, this team at the University of California, San Diego (UCSD) has demonstrated what is possible in engineering breakthroughs by developing the ForceSticker, an innovative force-measuring sticker. By integrating microcapacitors and commercial RFID IC tags, they created a device capable of measuring applied force and transmitting the information wirelessly.

Not only does this technology have potential for medical and industrial applications, but it can also be used to measure the weight of warehouse packages on the bottom. Through continued research and innovation, we have reason to believe that there will be more breakthroughs like this to improve our lives and work in the future.

Regarding product needs for NFC stickers, including RFID tags, Newbega can provide customers with high-quality products. You can visit our product categories to filter. We sincerely hope to have a good cooperative opportunity to help your business. Gain a better business advantage.

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