Multifunctional microscope provides a versatile way to observe soft matter

Studying surface interactions in soft matter can present a wide host of challenges, including large elastic deformations from interactions at the sample’s surface, particularly when measuring adhesion. To address the need for a platform that can characterize adhesion and surface interactions, a researcher group presents a new, highly versatile microscope in Review of Scientific Instruments that may provide a robust set of tools for examining soft materials.

With the multifunctional force microscope (MFM), forces are measured through fiber optic sensors that monitor the normal and lateral deflection of a cantilever. The instrument is mounted on an inverted microscope for in situ imaging that can be conducted in wet and dry environments. The MFM is capable of characterizing systems with large deformations, such as pressure sensitive adhesives, yet is sensitive enough to measure spatial perturbations on the scale of nanometers.

Linear microtranslation stages and a piezoelectric actuator precisely control the motion of the cantilever while another linear stage controls the lateral motion of the sample. With microtranslation stages, travel distances can span 25 millimeters with a minimum step size of 50 nanometers, while the piezoelectric motion touts 0.2 nanometer step sizes of its maximum range of 100 micrometers. Cantilevers mounted on the translation stage deliver sensitivity in measuring forces of over four orders of magnitude, from 50 micronewtons to 1 newton, and can work in fluids.

The team performed probe tack, friction and hydrodynamic drainage experiments to verify the microscope’s performance. Next they intend to incorporate interferometry to quantify elastic deformation.

Source: “A multifunctional force microscope for soft matter with in situ imaging,” by Paul Roberts, Georgia A. Pilkington, Yumo Wang, and Joelle Frechette, Review of Scientific Instruments (2018). The article can be accessed at https://doi.org/10.1063/1.5018332 .