By Josh Perry, Editor
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Researchers from Simon Fraser University (SFU) in British Columbia, Canada and the Swiss Federal Laboratories for Materials Science and Technology (Empa) in Dübendorf, Switzerland are collaborating on a new environmentally-friendly, 3-D printing process that uses wood-derived cellulose material instead of plastics to build wireless sensors.

SFU Mechatronic Systems Engineering professor Woo Soo Kim is collaborating with Swiss researchers to develop an eco-friendly 3D printable solution for producing wireless Internet-of-Things sensors. (Simon Fraser University)

According to a report from SFU, the research is focused on creating wireless sensors for IoT applications that can be easily disposed of without contamination. 3-D printing also provides flexibility in design and potentially greater functionality.

A second collaboration with the Daegu Gyeongbuk Institute of Science and Technology (DGIST) in South Korea has developed an embossing technology for imprinting circuit patterns onto a flexible polymer substrate, which is a key component of building electronic devices.

The research was recently published in Advanced Electronic Materials. The abstract read:

“As the wireless communication technologies are becoming more crucial for internet?of?things (IoT) electronic devices, sensors have also been equipped with wireless data collection. A conventional way to make wireless sensor systems is to develop active sensor devices with silicon?based chip technologies integrated with an amplifier, a battery, a converter, among others. However, it is difficult to generate disposable inexpensive flexible sensors with all these rigid components.

“Here, 3D printed disposable wireless ion selective sensor systems with unique form factors, high sensitivity, and flexibility are reported. A 3D printable conductive ink is designed and optimized with cellulose nanofibers by addition of silver nanowires for sustainable and biocompatible sensor applications. Polyimide film which has high surface hydrophobicity is used as a substrate for better resolution of printing.

“The 3D printed wireless sensor system includes inductor–capacitor circuits, and ion selective membrane electrodes, which can detect quantitative ion concentrations selectively. The change of ion concentrations is detected by measuring the magnitude of S₁₁, reflective coefficient at the resonant frequency of 2.36 GHz using a vector network analyzer.

“The demonstrated sensitivity is 3.4%/ m for ammonium ion (NH₄⁺).”