Molecular forces behind a strong bio-glue. A glue made from engineered polypeptides and surfactant showed strong adhesion in wet and dry conditions. SFA measurements quantified attraction between its components and helped identify the interactions responsible.
Direct measurement of anion–π adhesion in water. SFA measurements revealed strong adhesion associated with anion–π interactions in water. Simulations helped show how a cooperating cation–π interaction enables the effect.
Raman spectroscopy meets the miniature SFA. Researchers paired a miniature SFA (uSFA) with Raman microscopy to detect water near a confined Teflon–glass interface. The approach relates chemical information to surface separation and interaction forces at the nanoscale.
Exceptionally low friction from surfactant bilayers in hard water. Published in Langmuir, this study used a surface forces apparatus to shear surfactant-coated mica surfaces under load. The resulting film contained two adsorbed bilayers and achieved a friction coefficient of about 0.001 or less. The measurements indicate that sliding occurs between liquid-like hydrocarbon tails within the bilayers, revealing an unusual route to effective boundary lubrication.
Mixing ionic liquids to boost capacitance. This ACS Nano study Matt’s group at the Univ Wisconsin-Madison reports interfacial capacitance increases of up to 150% by mixing ionic liquids. Surface forces apparatus measurements found similar long-range force decay lengths in the pure liquids and an equimolar mixture, helping link the improvement to changes in local ion organization near the surface. The findings point toward electrolyte mixtures as a route to higher-energy supercapacitors.
TBD
Electrically controlled adhesion (2025). Researchers used an electrochemical SFA to show how applied potential reorganizes ions and water between coated gold and mica, switching the interaction between adhesion and repulsion. The findings suggest a way to control adhesion without chemically changing the surfaces. An electrochemical configuration is available with either the SFA2000 or uSFA.
Polymer adhesion to treated steel Researchers used an SFA in reflection geometry to measure adhesion between a polymer and differently treated stainless-steel surfaces. Paired with surface-chemistry analysis, the measurements show how treatment changes the polymer–metal interface. Although reflection mode SFA is possible using an SFA2000, the default configuration is transmission mode.
Nanosilica for stone restoration. Researchers used a modified SFA to measure how “nanosilica consolidants” strengthen individual mineral contacts. Combined with X-ray measurements, the force data reveal how cohesion develops during treatment of weathered stone.
In this work, researchers in the Department of Chemical and Materials Engineering at the University of Alberta, use a SurForce Surface Forces Apparatus (SFA) to directly measure the surface and interfacial interactions between protein coatings (force curve shown) and model foulants. Findings explore protein-based functional materials for various applications, such as molecule and virus detection, environmental monitoring, sensing, and interfacial antifouling mechanisms providing insights for designing novel antifouling surfaces for the marine, food, and biomedical industries.
Researchers in Xavier Banquy’s group at the University of Montreal used a SurForce surface forces apparatus to compare how bottlebrush polymers adhere to mica and to each other in different salt solutions. They found that cations affect polymer anchoring to mica, while multivalent anions can bridge opposing polymer layers. The work shows that ion identity, not just salt concentration, can control underwater adhesion.
How cartilage protects joints from wear. This PNAS cover article used a surface forces apparatus (SFA) to measure friction as porcine cartilage slid against glass. The experiments suggest that, under compression, hyaluronic acid becomes trapped at the contact and works with lubricin to form a protective boundary layer. Its most striking effect was preventing wear, with only a modest reduction in friction.
In this work, the SFA technique is used to investigate the effects of DNA concentration on the formation of single-stranded DNA (ss-DNA) films- a novel surface interaction study using an SFA2000.
Adsorption properties of poly(carboxylate ether) to negatively charged surfaces in high-salt conditions. Interaction forces between negatively charged surfaces in high-salt solutions with three commercial cement dispersants were directly measured with sub-nanometer resolution using an older SurForce MkII surface forces apparatus SFA customized by the author.
A great article published by Dong Woog Lee entitled Revisiting the Interaction Force Measurement Between Lipid Bilayers Using a Surface Forces Apparatus. We recommend reading this review, summarizing research of intermembrane forces using the Surface Forces Apparatus.
UCSB researchers find that the chemical topology of silica can influence the effectiveness of many chemical processes that use it.
Skeletal joints must provide lubrication under considerable load. Lubrication between two sliding surfaces in aqueous environments can be greatly enhanced by polyelectrolyte brushes.
Adhesive strength testing of modified siderophore cyclic trichrysobactin (CTC) in saline environments- varying lysine and catechol in a wet adhesive; A Sticky Situation.
SFA2000 configuration: Basic configuration- Piezoelectric Top Mount & Main Translation Stage.
Simultaneous measurements of membrane thickness and interaction forces during hemifusion using an SFA combined with fluorescence microscopy; Seeing the Action.
SFA2000 configuration: (FL-SFA) Piezoelectric Top Mount & Main Translation Stage with Fluorescence Microscope.
Adhesive forces between self-healing polymer surfaces under aqueous conditions with varying pH- role of catechol groups in wet adhesives; The Fix Is In
SFA2000 configuration: Basic configuration- Piezoelectric Top Mount & Main Translation Stage.
Myelin Basic Protein (MBP) adsorption by healthy and simulated diseased myelin bilayers- insights into demyelinating diseases; Unhealthy Attachments.
SFA2000 configuration: Piezoelectric Top Mount and Main Translation Stage Bottom Mount.
Ionic Liquid [C4mim][NTf2] charged surface screening indicative of a dilute weak-electrolyte (low-free-ion density) solution;Understanding the Energetics of Ionic Liquids.
SFA2000 configuration: Electrochemcial (EC) Top Mount with Main Translation Stage Bottom Mount.
Stick-slip friction as primary mechanism degrading articular cartiledge;Mechanics of Arthritus.
SFA2000 configuration: Friction Device Top Mount and Main Translation Stage Bottom Mount with addtiional strain gauging – (microtribometer configuration, does not require interferometry).
Surface Forces and Wetability
A fundamental understanding of the wettability of rock surfaces by crude oil and brine requires a good description of the interactions between the different materials. This aim was to measure those interactions and to establish their implications on the observed wetting behavior.
Probing Molecular Interactions of Asphaltenes in Heptol Using a Surface Forces Apparatus: Implications on Stability of Water-in-Oil Emulsions
These results provide insights into the fundamental understanding of molecular interaction mechanisms of asphaltenes in organic solvents and stabilization/destabilization behaviors of water-in-oil emulsions with asphaltenes.
Intermolecular and Surface Forces at Solid/Oil/Water/Gas Interfaces in Petroleum Production
Interaction forces between petroleum components (e.g., asphaltenes) and mineral solids in both organic solvents and aqueous solutions are reviewed and correlated to the wettability change of the reservoir solids.
Effects of Salinity on Oil Recovery (The “Dilution Effect”)
The primary aim of this study was to investigate the “dilution effect”, where dilution of the ionic concentration of the fluid injected into oil wells has been found to enhance oil recovery.
Fundamental Studies of Crude Oil-Surface Water Interactions and its Relationship to Reservoir Wettability
It is shown that in addition to van der Waals and electrostatic forces (included in the DLVO theory), polymer-like interactions of adsorbed asphaltene layers are involved in the overall process. It was further established that the concept of an intrinsically oil-wet or water-wet surface or reservoir cannot, in general, be correct: depending on the nature of the oil and brine, different species in a crude oil will adsorb on the mineral surfaces and at the oil-water interface, thereby determining the wetting behavior of a reservoir or rock.
Direct Measurements of Interactions and Viscosity of Crude Oils in Thin Films Between Model Clay Surfaces
These findings should have a direct bearing on the theory and practice of EOR technology, and in particular they indicate that pure hydrocarbons such as alkanes are poor models for naturally occurring crude oils.
In situ nano- to microscopic imaging and growth meachanism of electrochemical dissolution (e.g., corrosion) of a confined metal surface
This research into real-time, micro- and nanoscale mechanisms of corrosion provides valuable information that scientists can build upon, which may lead to models and predictions of how and when materials in confined spaces are likely to corrode.
These front-covers are either based on measurements taken using a Surface Force Apparatus (SFA), refer to the historical role SFAs have played in the direct measurement of oscillatory structural forces, or support data taken using an SFA through additional simulation and analysis.
NOV 1, 2016
A History of Nanobubbles
Langmuir, 32 (43)
DOI: 10.1021/acs.langmuir.6b02489
FEB 24, 2015
Developing a General Interaction Potential for Hydrophobic and Hydrophilic Interactions
Langmuir, 31 (7)
DOI: 10.1021/la502115g
DEC 26 2013
The Intersection of Interfacial Forces and Electrochemical Reactions
J. PHYSICAL CHEMISTRY B,177(51)(online)
DOI: 10.1021/jp408144g
NOV 28 2013
Brushes in Strong Polyelectrolytes in Mixed Mono- and Tri-Valent Ionic Media
at Fixed Total Ionic Strengths
SOFT MATTER, 9 (44) 10429-10656
DOI: 10.1039/C3SM90149A
SEP 21 2013
Simulation of edge facilitated adsorption and
critical concentration induced rupture of vesicles at a surface
SOFT MATTER, 9 (35) 8391-8610
DOI: 10.1039/C3SM90116E
AUG 6 2013
Brief History of Intermolecular and lntersurface Forces in Complex Fluid Systems
LANGMUIR, 29 (31) 9605-9619
DOI: 10.1021/la401002b
JUN 1 2013
Recent advances in gecko adhesion and friction mechanisms and
development of gecko-inspired dry adhesive surfaces
FRICTION, 1 (2) 114-129
DOI: 10.1007/s40544-013-0016-0
JULY 9 1997
Recent advances in gecko adhesion and friction mechanisms and
development of gecko-inspired dry adhesive surfaces
LANGMUIR, 13 (14) 3839-3848
DOI: 10.1021/la960942a
Sep 30 2007
Use of a surface forces apparatus to determine the energetics and dynamics of SNAREpin formation and characterized the different intermediate structures sampled by cognate SNAREs in the course of their assembly.
Nat Struct Mol Biol 14, 890–896 (2007)
DOI: 10.1038/nsmb1310
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