Related Experiment Video
Updated: Jul 2, 2026
06:07
Studying Large Amplitude Oscillatory Shear Response of Soft Materials
Published on: April 25, 2019
'Seeing' Strain in Soft Materials
Zhiyong Xia1, Vanessa D Alphonse2, Doug B Trigg3
1Applied Physics Laboratory, The Johns Hopkins University, Laurel, MD 20723, USA. Zhiyong.Xia@jhuapl.edu.
Molecules (Basel, Switzerland)
|February 6, 2019
Summary
A novel passive strain sensor using poly(dimethyl siloxane) (PDMS) and spiropyran (SP) can measure high-rate impact strains. This reversible color-changing sensor offers a new method for quantifying material deformation, potentially aiding traumatic brain injury research.
Area of Science:
- Materials Science
- Mechanical Engineering
- Biomedical Engineering
Background:
- Existing methods for measuring soft material strain under impact lack continuous 3D spatial distribution.
- High-rate impact testing of soft materials is crucial for understanding material behavior and failure.
Purpose of the Study:
- To develop a novel passive strain sensor for measuring impact-induced strains in soft materials.
- To demonstrate the sensor's capability to provide continuous 3D spatial strain data.
Main Methods:
- Incorporation of spiropyran (SP) mechanophore into poly(dimethyl siloxane) (PDMS) elastomer.
- Utilizing the reversible color change of SP in PDMS to quantify strain under high strain rates (up to 1500 s⁻¹).
- High-speed imaging to capture dynamic strain events.
Main Results:
- A novel PDMS-based passive strain sensor with covalently incorporated SP was successfully developed.
- The sensor demonstrated the ability to measure impact strains via a reversible color change at strain rates up to 1500 s⁻¹ within milliseconds.
- The SP incorporation at 0.25 wt% was found to be effective for strain measurement.
Conclusions:
- The developed passive strain sensor offers a new, continuous, and reversible method for quantifying high-rate impact strains in soft materials.
- This technology has significant potential for applications such as quantifying brain strain in traumatic brain injury research.
- The sensor overcomes limitations of existing technologies by providing continuous 3D spatial strain distribution data.
Related Concept Videos
01:22Problem Solving on Stress and Strain
Stress is a quantity that describes the magnitude of a force that causes deformation, generally defined as internal force per unit area. When forces pull on an object and cause its elongation, like the stretching of an elastic band, it is called tensile stress. When forces cause the compression of an object, it is known as compressive stress. When an object is being squeezed uniformly from all sides, like a submarine in the depths of the ocean, we call this kind of stress bulk stress (or volume...
01:24Stress-Strain Diagram - Ductile Materials
The stress-strain relationship in ductile materials such as structural steel or aluminium is intricate and progresses through several stages. When a specimen is loaded, it initially exhibits a linear length increase, depicted by a steep straight line on the stress-strain diagram. It indicates the material is elastically deforming and will return to its original shape once unloaded. However, when a critical stress value is reached, plastic deformation begins. This stage sees substantial...
01:19Thermal Strain
Thermal strain is a concept that arises when we consider how temperature changes affect structures. Unlike the conventional assumption that structures remain constant under load, real-world scenarios often involve temperature fluctuations that can significantly impact these structures. Consider a homogeneous rod with a uniform cross-section resting freely on a flat horizontal surface. If the rod's temperature increases, the rod elongates. This elongation is proportional to the temperature...
01:20Shearing Strain
The shearing strain represents a cubic element's angular change when subjected to shearing stress. This type of stress can transform a cube into an oblique parallelepiped without influencing normal strains. The cubic element experiences a significant transformation when exposed solely to shearing stress. Its shape alters from a perfect cube into a rhomboid, clearly demonstrating the effect of shearing strain. The degree of this strain is considered positive if it reduces the angle between the...
01:27Measurements of Strain
Strain quantifies the deformation of a material under force, typically measured as normal strain, which represents the change in length when compared with the original length. Electrical strain gauges are used for enhanced accuracy. These devices consist of a conductive wire mounted on a paper backing that adheres to the material's surface. These gauges operate on the piezoresistive effect, where the wire's electrical resistance changes in response to mechanical deformation. The strain gauge...
01:13Strain Energy
Strain energy is a fundamental concept in the field of materials science and structural engineering, describing the energy absorbed by a material or structure when it is deformed under load.
Consider a rod that is fixed at one end and subjected to an axial force at the free end. This axial force induces stress within the rod, leading to its elongation. As the axial force increases, so does the elongation of the rod, illustrating a direct relationship between the force applied and the resulting...
Consider a rod that is fixed at one end and subjected to an axial force at the free end. This axial force induces stress within the rod, leading to its elongation. As the axial force increases, so does the elongation of the rod, illustrating a direct relationship between the force applied and the resulting...