Sustainable Multifunctional Biface Sensor Tag

In this article, a sustainable, multifunctional, low-cost, wireless sensor tag is presented. The sensor tag combines three different environmental sensors in one single platform for the dedicated purpose of wireless structural health monitoring of a variety of applications. However, the adaptive design allows an integration of different sensors depending on the specific sensing task. The material consumption is minimized by double-sided printing, resulting in compact, resource-efficient sensor solutions. On one side, the tag is equipped with a printed antenna, a fully passive silicon-based NFC chip and a carbon-based strain sensor, while the environmental sensors for humidity and temperature are printed on the other side. Due to its low cost, the usage of environmentally friendly materials and the absence of a battery, the biface sensor tag is a milestone in the field of wireless, sustainable electronics for ubiquitous sensing applications.
The fabrication itself comprises a series of processes with a focus on efficient additive manufacturing. The device consists of a combination of inkjet- and screen-printed sensors, an inkjet-printed antenna, and a silicon-based chip for passive read-out, which is integrated using a non-conductive adhesive.
The characterization of the three sensors shows sensitivity values and characteristics comparable to those found in literature and industrially manufactured sensors. The utilization of a smartphone for reading out the sensor signals further emphasizes the sustainable approach of this sensor system.