Highly Sensitive, Stretchable, and Adjustable Parallel Microgates-Based Strain Sensors

Abstract

The demand for stretchable strain sensors with customizable sensitivities has increased across a spectrum of applications, spanning from human motion detection to plant growth monitoring. Nevertheless, a major challenge remains in the digital fabrication of scalable and cost-efficient strain sensors with tailored sensitivity to diverse demands. Currently, there is a lack of simple digital fabrication approaches capable of adjusting strain sensitivity in a controlled way with no changes to the material and without affecting the linearity. In this study, parallel microgates-based strain sensors whose strain sensitivity can be adjusted systematically throughout an all-laser-based fabrication process without any material replacement are presented. The technique employs a two-step direct laser writing method that combines the well-established capabilities of laser ablation and laser marking, boasting a varying gauge factor of up to 433% (GF  =  168), while paving the way for the mass production of nanocomposite strain sensors. Parallel microgates-based strain sensors exhibit a remarkable signal-to-noise ratio at ultralow strains (ɛ  =  0.001), rendering them ideal for monitoring the gradual growth of plants. As an application demonstration, the proposed sensors are deployed on tomato plants to capture their growth under varying planting conditions including hydroponic and soil mediums, as well as diverse irrigation regimens.