Determination of Coefficient of Friction of Soft Materials

The friction coefficient has a significant impact on the process and the material. Understanding soft material friction has become increasingly relevant as a result of the needs of healthcare, biomedicine, and other industries, the coupling of soft materials and technology, and the study of interacting biological interfaces. Determining the coefficient of friction for soft materials like polymers, tissue paper, or contact lenses is difficult.

Alfa Chemistry is particularly interested in the interaction of soft substances, such as the interaction of tissues with other materials. We specialize in soft material characterization and provide one-of-a-kind microtribology services.

Learn About Friction Force Microscopy

Microtribology is primarily concerned with determining the friction force between two contacting surfaces in relative motion. Friction and wear are both caused by the applied force. As a result, it's critical to study soft materials using non-destructive friction measurement techniques. Friction force microscopy (FFM) based on atomic force microscopy (AFM) is a great technology for such microtribology applications. With a sensitivity of several piconewtons, the lateral force between the tip of the micro-machined cantilever and the sample can be properly quantified.

Fig 1. Scanning electron microscopy images of the sharp tip and colloidal probes glued onto AFM cantilevers. (a) Commercial AFM cantilevers made from silicon or silicon nitride; (b) polydimethylsiloxane (PDMS); (c) borosilicate glass; (d) polyethylene (PE). (Liamas E, et al. 2020)

It uses the two-leg cantilever's vertical deflection to set the normal force and determine the frictional force at the same time. The difference in the reflection of the laser beam on two small mirrors can be observed using an optical fiber. The spring constant multiplies the change in distance between the fiber and the mirror and converts it to force. The friction coefficient is calculated by dividing the friction force by the normal force.

Friction Force Microscopy of Alfa Chemistry

Alfa Chemistry offers a tribological examination of soft materials such as contact lenses, cartilage, skin, blood vessels, and more through FFM. The following are some of the advantages of this method of analysis:

• Analyzing biological systems and very thin layers is achievable thanks to the little force applied to the macroscopic sample.
• It may be used to measure both controlled and uncontrolled air humidity, as well as all liquid media under a variety of biologically relevant situations.
• Not only very hard (metals, ceramics) but also very soft materials can be evaluated (such as polymers, biological tissues)
• Spherical, flat, cylindrical, and curved shapes are all possible.
• Long-term research suitable

For example, our micro-tribology technology can be used to:

• Comparison of contact lenses, for example, involves measuring the friction force on the polymer surface.
• Determine the wear resistance of thin films on metals, such as corrosion inhibitors.
• Research into the production of surface lubricating films, such as those seen in shampoo or eye drops, in real-time.
• Analysis of lubrication systems, such as needle anti-friction coatings, cosmetic product formulas, and intra-articular formulations

Reference

• Liamas E, et al. (2020). "Probing the Frictional Properties of Soft Materials at The Nanoscale." Nanoscale. 12: 2292-2308.