Rapid Fabrication of Flexible and Stretchable Strain Sensor by Chitosan‐Based Water Ink for Plants Growth Monitoring

Abstract

Rapid fabrication of flexible and stretchable sensors is essential for the emerging applications of wearable devices. In this study, a chitosan‐based water ink realizes fabrication of flexible and stretchable stain sensor by simply writing the ink and leaving it to dry for ≈15 min at room temperature. It is found that chitosan is an excellent binding material. The fabricated sensor shows an excellent gauge factor of 64 within strain 1%–8%, and can be stretched up to 60%. More importantly, the sensor can be directly written on the subject, and sensors written on plants show that plants can response to mechanical injuries within a few minutes. These results show that this method reduces the energy and time consumption in the fabrication procedure, realizes direct fabrication of sensors on subjects for wearable monitoring, and meets the requirements for personalized and on‐site applications. So, this chitosan‐based ink provides an attractive strategy for the fabrication and application of wearable devices.

Compliant plant wearables for localized microclimate and plant growth monitoring

“…19 Sensors with GF above 200 are often limited by a stretchability of 5%. 20,21 Other highly stretchable strain sensors based on CNT networks show a GF = 0.82 for stretchabilities from 0% up to 40% strain 22 and often suffer from nonlinearity and high hysteresis, 23 while a more recent study on monitoring fruit growth using ink-based stretchable strain sensors displayed a gauge factor of GF = 64, 13 but limited in terms of practicality and linearity up to only 8% strain. Therefore, a balance between sensitivity and desired stretchability needs to be attained depending on the application of interest.…”

“…More recently, a study attempted at monitoring plant growth by using chitosan-based water ink to print strain sensors on the plants' already grown fruits/seeds. 13 While this method can measure the overall expansion of exclusively the fruits, it does not provide concrete information about the growth of the plant. Although the printed sensor provides great adhesion with the fruit, the measured resistance is affected by general expansion of the seed and hence there is no control on identifying what growth is.…”

A Behavior‐Learned Cross‐Reactive Sensor Matrix for Intelligent Skin Perception

“…More importantly, since most of the current e‐skin technologies are essentially based on “lock and key” approaches, the numeric data signals measured from the superposed stimuli could not be cross‐operated with each other, leaving the difficulty of decoupling interference of intermixed signals and of integrating cross interferences for recognizing the behavior of each stimulus. [ 28–32 ] To address these issues, in a previous work, a field‐effect transistor composed of a piezo‐pyroelectric gate dielectric and a piezo‐thermoresistive organic semiconductor channel was utilized, showing the simultaneous response to two stimuli of pressure (or strain) and temperature. However, this approach is only available for a limited range of deformability, resulting in a restricted range for practical applications.…”

Chitosan‐Based, Biocompatible, Solution Processable Films for In Vivo Localization of Neural Interface Devices

“…CS is increasingly being used in applications involving neural tissue, functioning as a component of hydrogels for neural tissue engineering and nanoparticles for neurologic drug delivery . Recently, it has also been incorporated into neural interface devices .…”

“…[10,11] CS is increasingly being used in applications involving neural tissue, functioning as a component of hydrogels for neural tissue engineering and nanoparticles for neurologic drug delivery. [12][13][14][15] Recently, it has also been incorporated into neural interface devices. [7,16,17] Generally, neural interface devices are critical for transducing neural signals and form the basis for neurophysiological experimentation.…”