Multisensitive Swelling of Hydrogels for Sensor and Actuator Design

Abstract

A main characteristic of hydrogels is their multisensitivity, i.e., the material's capability to respond to multiple stimuli such as temperature, chemical concentration or light. Most modeling approaches to swelling in the literature deal with the monosensitive behavior of hydrogels. Herein, two approaches to the modeling of multisensitive sensors and actuators are proposed: the N‐field method and the trajectory method. They are derived using experimental data of the bisensitive hydrogel [net‐P(AMPS‐co‐NiPAAm)]‐sipn‐PAMPS. It is sensitive to sodium salt concentration and temperature. For the trajectory method, the procedure for the generalized representation of the material behavior is presented. Applying the Temperature Expansion Model, this is implemented in Abaqus and the results of verification simulations are given. The trajectory method is capable of representing the multisensitive behavior of hydrogels. The method is easy to implement in commercial Finite Element tools based on the free‐swelling data of the material. Simulation results of the free swelling are in excellent agreement with the given calibration data. The obtained swelling behavior can be combined with mechanical loads and arbitrary boundary conditions to form more complex setups. The current work allows a deeper understanding of complex multifunctional materials, such as hydrogels, and their application in sensor or actuator devices.

Versatility of Hydrogels: From Synthetic Strategies, Classification, and Properties to Biomedical Applications

“…When enough water enters the hydrogel framework, the shiny state changes into a rubbery condition known as expanding. The dissemination interaction is responsible for the passage and exit of water from the hydrogel matrix [ 74 , 75 , 76 ]. The swelling and de-swelling of hydrogels are shown in Figure 3 .…”

“…The usage of in situ forming scaffolds is one option for this procedure. After injecting DDS into the affected cord region, viscoelastic hydrogels quickly convert from liquid to gel and conform to the tissue at the injury site [ 76 ]. In vivo conversion of fluid hydrogels to the gel, the structure will bridge the small split between spinal string tissue and, surprisingly, cut across segments created after SCI.…”

Smart materials in architecture for actuator and sensor applications: A review

“…Examples for such stimuli are pH value, temperature, specific ions, or light exposure. One of their most interesting characteristics is that they can be designed in such a way, that multisensitivity (Ehrenhofer et al, 2020) is possible—that means that a hydrogel will respond only if two stimuli occur simultaneously. They exhibit very large strains and high energy densities.…”

High Performance Double Conductive Network Hydrogel Based on Soaking Strategy for Supercapacitors

“…Ion sensors usually need to bear periodic mechanical load to adapt to the dynamic environment, which inevitably leads to mechanical damage and greatly shortened service life. [7][8][9][10][11] Therefore, it is necessary to develop ionic conductors with high tensile strength and excellent DOI: 10.1002/mame.202100652 fatigue resistance. In practical use, these ionic conductors can synchronously detect changes in external deformation and transform those changes into electrical signals with high accuracy and sensitivity.…”