Printed Strain Sensors Based on an Intermittent Conductive Pattern Filled with Resistive Ink Droplets

Daniel Zymelka,Takahiro Yamashita,Xiuru Sun,Takeshi Kobayashi

doi:10.3390/s20154181

Daniel Zymelka, Takahiro Yamashita + Show 2 more

Open Access

https://doi.org/10.3390/s20154181

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Abstract

In this study, we demonstrate a strain sensor fabricated as a hybrid structure of a conductive intermittent pattern with embedded single droplets of a functional resistive ink. The main feature of our proposed sensor design is that although the intermittent pattern comprises the majority of the entire sensor area, the strain sensitivity depends almost selectively on the resistive droplets. This opens up the possibility for fast and inexpensive evaluation of sensors manufactured from various functional materials. As the use of resistive ink was limited to single droplets deposition, the required ink amount needed to build a sensor can be considerably reduced. This makes the sensors cost-effective and simple for fabrication. In this study, our proposed sensor design was evaluated when a carbon-based ink was used as the resistive material incorporated into an intermittent structure made of silver. The developed strain sensors were tested during bending deformations demonstrating good strain sensitivity (gauge factor: 7.71) and no hysteresis within the investigated strain range.

Highlights

Strain sensors have a long history of being used in various engineering fields
As printable constantan-based inks are not commercially available, printed strain sensors are generally manufactured from other strain-sensitive materials based on graphite [4], silver [5], PEDOT:PSS [6,7,8], graphene [9], carbon nanotubes (CNT) [10]
We evaluate an alternative concept for a strain sensor whose design is based on a hybrid construction of a conductive intermittent pattern with embedded single droplets of resistive functional ink, i.e., an ink used to build electrically resistive elements in the sensor structure providing strain sensitivity

Summary

Introduction

Strain sensors have a long history of being used in various engineering fields. Aside from aerospace and automotive applications, strain sensors are widely used to monitor civil infrastructures [1,2]. Constantan-based sensors are of particular interest, mainly owing to their low thermal coefficient of resistance. Such sensors are generally fabricated using a photolithography etching process that involves several fabrication steps and materials. Recent progress in additive manufacturing, widely used for flexible printed electronics [3], opens up new possibilities for the cost-effective fabrication of sensors using diverse materials. As printable constantan-based inks are not commercially available, printed strain sensors are generally manufactured from other strain-sensitive materials based on graphite [4], silver [5], PEDOT:PSS [6,7,8], graphene [9], carbon nanotubes (CNT) [10]

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