Measuring adhesion on rough surfaces using atomic force microscopy with a liquid probe
At a Glance
Section titled âAt a Glanceâ| Metadata | Details |
|---|---|
| Publication Date | 2017-04-10 |
| Journal | Beilstein Journal of Nanotechnology |
| Authors | Juan V. Escobar, Cristina Garza, Rolando Castillo |
| Institutions | Universidad Nacional AutĂłnoma de MĂ©xico |
| Citations | 14 |
| Analysis | Full AI Review Included |
Expert Material Analysis: Adhesion Measurement on Engineered Diamond Surfaces
Section titled âExpert Material Analysis: Adhesion Measurement on Engineered Diamond Surfacesâ6CCVD Ref: MPCVD-ADHESION-2017-V1.0 Source Paper: Measuring adhesion on rough surfaces using atomic force microscopy with a liquid probe (Beilstein J. Nanotechnol. 2017) Application Focus: Advanced surface characterization, Superhydrophobicity/Supersolvophobicity, Wetting Phenomena, Printing Technology.
Executive Summary
Section titled âExecutive SummaryâThis documentation analyzes a research procedure that utilizes a modified Atomic Force Microscope (AFM) colloidal probe technique, replacing the standard solid sphere with a micrometric liquid mercury drop, to measure adhesion forces ($F_{adh}$) on highly engineered rough surfaces.
- Novel Methodology: Adhesion forces are measured during jump-off-contact between a liquid mercury probe (10-30 ”m diameter) and rough test surfaces using a conventional AFM system.
- Key Material Focus: Experiments relied heavily on Boron-Doped Microcrystalline Diamond (PCD) films, modified via thermal oxidation (850 °C) to achieve multi-scaled surface roughness.
- Roughness Correlation: The study validates that increasing surface roughness inversely correlates with adhesion force, achieving extremely low $F_{adh}$ values (maximum likelihood 5.7 nN) on the highly modified multi-scaled diamond surface.
- SCD Control: Comparison measurements utilized Boron-Doped Polished Single-Crystal Diamond (SCD) as a low-roughness control, yielding significantly higher adhesion forces (40.7 ± 1.5 nN).
- Critical Environment: All measurements were conducted in a dry Nitrogen (N2) atmosphere to eliminate spurious water capillary interactions, ensuring reliable results applicable to fundamental wetting theory.
- Commercial Relevance: This procedure provides essential microscopic data crucial for developing engineering solutions related to self-cleaning surfaces, drag reduction, and optimized print-engine components.
Technical Specifications
Section titled âTechnical SpecificationsâThe following hard data was extracted from the experimental procedures and results section of the paper, detailing the materials and performance metrics.
| Parameter | Value | Unit | Context |
|---|---|---|---|
| Diamond Film Thickness | 7 | ”m | Starting Boron-doped microcrystalline film (PCD) |
| Diamond Film Substrate | Silicon (Si) | Wafer | Substrate for PCD growth |
| Oxidation Temperature | 850 | °C | Thermal treatment to induce multi-scaled roughness |
| Oxidation Time | 10 | min | Duration of thermal treatment |
| Silicon Peak Pitch (TGT1 Grating) | 3 ± 0.01 | ”m | Control surface lattice spacing |
| Silicon Peak Radius (TGT1 Grating) | 10 | nm | Control surface tip sharpness |
| Mercury Drop Diameter (Range) | 10 - 30 | ”m | Size of the liquid probe |
| Measurement Atmosphere | Dry N2 or < 1 x 10-4 | Pa | Inert atmosphere/Vacuum |
| Average Fadh (Smoother Polished SCD) | 40.7 ± 1.5 | nN | Boron-doped polished single-crystal natural-type diamond |
| Fadh (Rough PCD / Hg Drop) | 5.7 | nN | Maximum likelihood pull-off force for multi-scaled rough diamond |
| Unit Fadh (Rough PCD / Single Protrusion) | 2.8 | nN | Calculated force unit for sub-micrometer protrusion interaction |
| Contact Angle (Hg / Polished BDD) | 155 | ° | Essential parameter for Dupré equation calculation |
Key Methodologies
Section titled âKey MethodologiesâThe core experiment relied on high-precision material engineering and controlled environmental operation of the AFM setup.
- Base Material Preparation: A 7 ”m thick Boron-doped microcrystalline diamond (PCD) film, initially grown on a silicon substrate, was used as the primary rough test surface.
- Roughness Modification: The PCD film underwent thermal oxidation (heating at 850 °C for 10 minutes) to modify its topology, generating the crucial multi-scaled rough, Hg-phobic surface characterized by sub-micrometer protrusions (pyramid-like structures decorated with ca. 100 nm high features).
- Cantilever Modification: Commercial tipless cantilevers were functionalized by coating a small area of the lower surface with a sticky adhesive (pressure-sensitive tape dissolved in chloroform).
- Liquid Probe Attachment: Cleaned, double-distilled mercury was prepared. Droplets (10-30 ”m) were selected and attached (pinned) firmly to the functionalized tipless cantilever under careful handling to avoid contamination.
- Environmental Control: AFM force-displacement curves were obtained using a scanning probe microscope (JSTM-4200 JEOL) operating within an integrated chamber maintained under dry nitrogen (N2) atmosphere to suppress measurement artifacts from water condensation and capillary forces.
- Force Determination: Cantilever spring constants ($k_c$) were precisely calibrated using the thermal noise method. Pull-off force ($F_{adh}$) was calculated from the jump-off-contact discontinuity observed in the force-displacement curves.
6CCVD Solutions & Capabilities
Section titled â6CCVD Solutions & CapabilitiesâThe findings of this paper underscore the critical need for highly controlled, customized diamond materialsâspecifically Boron-Doped Diamond (BDD)âto drive fundamental research in surface adhesion, wetting, and functional coatings. 6CCVD is uniquely positioned to supply and enhance the materials required for this and similar research pathways.
Applicable Materials
Section titled âApplicable MaterialsâTo replicate and extend the research into liquid-solid interactions on supersolvophobic surfaces, 6CCVD recommends the following high-purity MPCVD diamond materials:
- Boron-Doped Polycrystalline Diamond (BDD PCD): Directly addresses the paperâs core test material requirement. 6CCVD can supply BDD PCD films with customizable thickness from 0.1 ”m up to 500 ”m, matching the 7 ”m thickness used, and on various substrate materials up to 125 mm in diameter for scalable experiments.
- Optical/Electronic Grade Single Crystal Diamond (SCD): Required for low-roughness control measurements. 6CCVD provides highly polished SCD wafers with surface roughness Ra < 1 nm, allowing researchers to establish precise baselines for adhesion (as demonstrated by the 40.7 nN polished SCD control measurement).
- Custom Substrates: We provide diamond films grown on specialized substrates (e.g., Si, Si3N4, custom substrates) required for integration into complex experimental setups like functionalized AFM cantilevers.
Customization Potential
Section titled âCustomization PotentialâThe experimental success depends on precise material preparation and geometry. 6CCVD offers specialized services to meet these advanced engineering requirements:
- Custom Dimensions and Shapes: While the paper references only small-scale measurements, 6CCVD provides laser cutting and etching services to generate custom-sized wafers, plates, or precise geometries (such as cantilever attachment points or micro-patterns) needed for liquid probe or colloidal probe experiments.
- Metalization Services: Although the mercury drop utilized adhesive, future functionalization (e.g., creating stable interfaces for different liquid probes) may require metal contact layers. 6CCVD offers in-house deposition of standard and refractory metals including Au, Pt, Pd, Ti, W, and Cu for reliable electrical or structural functionalization of diamond surfaces.
- Polishing and Roughness Control: To fine-tune the influence of roughness on $F_{adh}$ (as demonstrated by the strong roughness correlation in the paper), 6CCVD provides precision polishing (Ra < 1nm for SCD; Ra < 5nm for inch-size PCD) or, alternatively, as-grown surfaces tailored to maximize or minimize roughness parameters.
Engineering Support
Section titled âEngineering SupportâUnderstanding the complex elastic interactions between the liquid probe, the cantilever, and the engineered diamond surface ($k_c$, $k_d$, $k_{eff}$) requires deep material science knowledge. 6CCVDâs in-house PhD-level engineering team is available to assist customers with:
- Material Selection: Consulting on the optimal doping levels, crystalline structure (SCD vs. PCD), and substrate choice required to replicate or extend adhesion studies, such as optimizing diamond surfaces for supersolvophobicity or functional fluid delivery systems.
- Process Integration: Guidance on handling and preparation (e.g., high-temperature thermal treatments like the 850 °C oxidation mentioned) to ensure the integrity and quality of 6CCVD diamond materials are maintained during post-processing.
For custom specifications or material consultation, visit 6ccvd.com or contact our engineering team directly.
View Original Abstract
We present a procedure to perform and interpret pull-off force measurements during the jump-off-contact process between a liquid drop and rough surfaces using a conventional atomic force microscope. In this method, a micrometric liquid mercury drop is attached to an AFM tipless cantilever to measure the force required to pull this drop off a rough surface. We test the method with two surfaces: a square array of nanometer-sized peaks commonly used for the determination of AFM tip sharpness and a multi-scaled rough diamond surface containing sub-micrometer protrusions. Measurements are carried out in a nitrogen atmosphere to avoid water capillary interactions. We obtain information about the average force of adhesion between a single peak or protrusion and the liquid drop. This procedure could provide useful microscopic information to improve our understanding of wetting phenomena on rough surfaces.