Application

Soft-Material Testing

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Application Overview

Polymers, foams, aerogels, and bio-inspired substances like hydrogels are often classed together as Soft materials. These highly-deformable materials have many unique mechanical behaviors like viscoelasticity and excellent damping.

Understanding their mechanical behavior is crucial for biomaterials and life sciences and their applications in health-related and medical fields.

The ‘softness’ of these materials means that large displacements are made even with very small forces. FemtoTools meets this challenge with its industry-leading force resolution and long-range displacement capabilities.

<p>Close-up of a spherical ruby indenter tip used for soft material characterization.</p>

<p>Graph displaying the relationship between applied force and displacement for PDMS material testing.</p>

<p>Graph showing force-deformation relationship of a hydrogel microcapsule during a compression test, indicating stiffness and rupture points.</p>

Application Examples

Compression of Hydrogels

Piezoresistive Cantilever Testing

Graph showing force-deformation relationship of a hydrogel microcapsule during a compression test, indicating stiffness and rupture points.

A common sensing principle of MEMS-based sensors involves the inclusion of a piezoresistive element into the sensing structure. As the sensing element is strained, the electrical resistance of the piezoresistive element changes.

To increase the efficiency of dip-pen nanolithography systems, the MEMS chip shown here features an array of six cantilevers for parallel writing. To correct for the tilt angle between the cantilever array and the sample substrate, each cantilever is equipped with a piezoresistive sensor that measures the contact force of each cantilever. The piezoresistive elements have been fabricated through ion implantation, and a Wheatstone bridge has been integrated into the system to accurately convert the small resistance change into a voltage change.

In this application example, the stiffness of each cantilever is investigated in an automated manner. Consistent stiffness within the array is important property that determines the performance of the MEMS chip.

Tensile Test of Fibers

Tensile Test of Micro-fibers

Microfibers are used to reinforce composites & optical fibers and to create strong, lightweight components. To understand their mechanical behavior, micro-tensile testing is the ideal method.

In this application example, silica microfibers produced using roller electrospinning are investigated using micro-tensile testing. The fiber is gradually stretched until it becomes straight and then further elongated to measure its maximum elongation, maximum yield strength, and stiffness. Relaxation behavior and cyclic testing was also performed, providing insight into the durability and application potential of the silica fiber.

Biological Applications

In-Liquid Micro-scale Testing of Plant Root Hairs

How do plants grow? To understand the mechanics of root growth in soil, micro-tensile testing was applied to delicate plant root hairs to measure their tensile strength, yield strength, and other properties.

This application example revealed that upon loading, root hairs partially fracture and form a helical shape, instead of failing completely. These observations offer valuable insights into the mechanical and structural behavior of plant root hairs, with potential implications for biology, agriculture, and materials science.

In-Liquid Testing

In-Liquid Tensile Testing of Fibronectin Fibers

Fibronectin (Fn) fibers are crucial for wound repair, a critical application in medicine and healthcare. Using tensile testing in a simulated physiological environment, the mechanical properties of Fn fibers can be determined in the laboratory before human trials.

In this application example, the folding and unfolding mechanisms of Fn fibers were observed by deploying them on microfabricated PDMS grids, rehydrating them in PBS buffer, and applying micro-tension. This innovative approach blends biology and engineering to offer insights into the functions of biological materials, paving the way for advancements in healthcare solutions.