Contents

Medical Device Industry
The Practical Guide to Surface Science (2026)

D54c15105cfe94f786c500e4091d6ea65457608fde49ba183c8f862814a54249?s=100&d=m
Written by
Dr Amit Pratap Singh
PhD, Delhi University Post Doc - AIST Japan
Guest Author
Read More
alidad
Reviewed by
Dr Alidad Amirfazli
Dr. Amirfazli, a leading expert in surface wetting and superhydrophobic coatings, has 250+ publications, edits Advances in Colloid and Interface Science, and has received multiple research awards.
Scientific Advisor & Co-founder
Read More
D54c15105cfe94f786c500e4091d6ea65457608fde49ba183c8f862814a54249?s=100&d=m
Written By

Dr Amit Pratap Singh

Guest Author

PhD, Delhi University

Post Doc - AIST Japan

alidad
Reviewed By

Dr Alidad Amirfazli

Scientific Advisor & Co-founder

Dr. Amirfazli, a leading expert in surface wetting and superhydrophobic coatings, has 250+ publications, edits Advances in Colloid and Interface Science, and has received multiple research awards.

Featured Studies & Publications

Research Paper Contact angle measurement with a smartphone
Research Paper Surface tension measurement with a smartphone using a pendant drop

This is a practical guide to Surface Science for researchers working in the Medical Device Industry.

In this all-new guide you’ll learn all about:

  • Crucial surface science principles
  • The significance of surface science measurements for the Medical Device industry
  • Applicable ASTM Standards & Guidelines

Let’s dive right in.

Medical Device

Contents

measurement

Contact Angle Measurement

tension

Surface Tension Measurement

energy

Surface Energy Measurement

sliding angle

Sliding Angle Measurement

realworld

Real World Applications

standardand guide

Standards and Guidelines

Executive Summary

What it covers: How medical device teams use contact angle, surface free energy, surface tension and sliding angle on implants, catheters, tubing and biomaterials. Each measurement is tied to a real device problem, a guidance document and published client work.
Key insights: In a Harvard School of Dental Medicine study in Biomimetics, plasma treatment cut saline contact angle on machined titanium from 83.1 to 24.1 degrees. In two Universidad Católica de Temuco papers, coatings on silicone catheters lowered water contact angle by 22 to 35 degrees. Contact angle shows that a surface changed; it does not by itself show a clinical benefit.
Business value: A contact angle check on the line catches a missed plasma step, a residue or a weak coating before parts move on. Zeus ran its own Gage R&R on the Dropometer and it passed.
Standards to follow: The FDA 510(k) guidance for contact lens care products describes finding the critical micelle concentration from surface tension across a dilution series. The Dropometer uses the pendant drop method for that surface tension step. Your own validation and regulatory pathway decide how results are used.
Bottom line: Use contact angle to check every surface step that affects wetting, from plasma treatment to coating cure. Start with the step that fails most often, then book a 15 minute demo to try it on your own parts.

Chapter 1: Introduction

In medical devices, many failures start at the surface. A catheter coating that does not wet evenly can fail in use. An implant that picked up residue during cleaning can behave differently from the one that passed testing.

These are the places where wetting decides yield in medical device work:

The Dropometer contact angle and surface tension kit measures contact angle, surface and interfacial tension, surface free energy and sliding angle with one portable setup. Its method was validated against a KRUSS DSA100E in two peer reviewed papers. If you are new to the terms, start with wettability.

We use the following surface properties to understand the behavior of Medical Device products and improve their quality.

Chapter 2: Contact Angle Measurement

The contact angle quantifies the wettability of a surface by representing the angle between a liquid’s surface and a solid surface.
Dropletlab Research

Sample Image taken from Droplet Lab Tensiometer.

Young – Laplace Method

  • 1. This method uses the whole drop profile to calculate the contact angle value.
  • 2. This method is only compatible with an axisymmetric drop, which is not always seen in practice because a needle is typically inserted into the drop to increase or decrease the drop volume.
  • 3. This method yields more consistent results than the polynomial fitting method.

Polynomial Method

  • 1. This method uses only a portion of the drop profile to calculate the contact angle value.
  • 2. This method is compatible with both axisymmetric and non-axisymmetric drops.
  • 3. The measurement results of this method are less consistent, as they can be influenced by local surface imperfections.
Dynamic Contact Angle

Ideally, when we place a drop on a solid surface, a unique angle exists between the liquid and the solid surface. We can calculate the value of this ideal contact angle (the so-called Young’s contact angle) using Young’s equation. In practice, due to surface geometry, roughness, heterogeneity, contamination, and deformation, the contact angle value on a surface is not necessarily a single consistent value but rather falls within a range. The upper and lower limits of this range are known as the advancing and receding contact angles, respectively. The values of advancing and receding contact angles for a solid surface are highly sensitive to many parameters, such as temperature, humidity, homogeneity, and minor contamination of the surface and liquid. For example, the advancing and receding contact angles of a surface can differ at different locations.

Dynamic Contact Angle versus Static Contact Angle

Practical surfaces and coatings naturally show contact angle hysteresis, indicating a range of equilibrium values. When we measure static contact angles, we get a single value within this range. Solely relying on static measurements poses problems, like poor repeatability and incomplete surface assessment regarding adhesion, cleanliness, roughness, and homogeneity.

In practical applications, we need to understand how easily a liquid spreads (advancing angle) and how easily it is removed (receding angle), such as in painting and cleaning. Measuring advancing and receding angles offers a holistic view of liquid-solid interaction, unlike static measurements, which yield an arbitrary value within the range.

This insight is crucial for real-world surfaces with variations, roughness, and dynamics, aiding industries like cosmetics, materials science, and biotechnology in designing effective surfaces and optimizing processes.

Learn how Contact Angle measurement is done on our Tensiometer

For a more complete understanding of Contact Angle measurement, read our Contact Angle measurement: The Definitive Guide

Contact Angle measurement: The Definitive Guide

Open Benchmark Data: Contact Angle & Surface Energy

These reference measurements show how deionized water wets four standard substrates measured with the Droplet Lab Dropometer. Use them as visual and numerical benchmarks when you're checking your own sample preparation, treatments, and chemistry.

Full contact angle and surface energy datasets (including additional liquids and statistics) are available on our dataset hub.

Glass - DI Water
Glass - DI Water
Nylon - DI Water
Nylon - DI Water
PMMA - DI Water
PMMA - DI Water
Teflon - DI Water
Teflon - DI Water

The droplet images above are taken from the same benchmark series as our open dataset. For each substrate and probe liquid we report:

● Advancing and receding contact angles (and hysteresis)
● Derived surface energy (SFE) values based on multi-liquid measurements
● Measurement conditions, uncertainties, and sample preparation details

Comparing your own droplet shapes and angles against these references is a fast way to spot contamination, treatment drift, or unexpected changes in wettability.

Explore the full benchmark datasets (contact angle + surface energy)

Measurements were performed with the Droplet Lab Dropometer under controlled laboratory conditions. Treat these values as sanity checks and starting points for your own process targets, not as product specifications.

Chapter 3: Surface Tension Measurement

This property measures the force that acts on the surface of a liquid, aiming to minimize its surface area.

Surface Tension Measurement

Sample Image taken from Droplet Lab Tensiometer

Dynamic Surface Tension

Dynamic surface tension differs from static surface tension, which refers to the surface energy per unit area (or force acting per unit length along the edge of a liquid surface).

Static surface tension characterizes the equilibrium state of the liquid interface, while dynamic surface tension accounts for the kinetics of changes at the interface. These changes could involve the presence of surfactants, additives, or variations in temperature, pressure, and composition at the interface.

When to use Dynamic Surface Tension Measurement

Dynamic surface tension is essential for processes that involve rapid changes at the liquid-gas or liquid-liquid interface, such as droplet and bubble formation, coalescence (change in surface area), the behavior of foams, and the drying of paints (change in composition, e.g., evaporation of solvent). It is measured by analyzing the shape of a hanging droplet over time.

Dynamic surface tension applies to various industries, including cosmetics, coatings, pharmaceuticals, paint, food and beverage, and industrial processes, where understanding and controlling the behavior of liquid interfaces is essential for product quality and process efficiency.

Learn how Surface Tension measurement is done on our Tensiometer

For a more complete understanding of Surface Energy measurement, read our Surface Tension measurement: The Definitive Guide

Surface Tension measurement: The Definitive Guide

Chapter 4: Surface Energy Measurement

Surface energy refers to the energy required to create a unit area of a new surface.
231

Sample Image taken from Droplet Lab Tensiometer

Learn how Surface Energy measurement is done on our Tensiometer

For a more complete understanding of Surface Energy measurement, read our Surface Energy measurement: The Definitive Guide

Surface Energy measurement: The Definitive Guide

For benchmark contact angle and surface energy values on glass, nylon, PMMA, and Teflon, see the Open Benchmark Data panel above or visit our Dataset Hub for full CSV downloads.

Dataset Hub

Chapter 5: Sliding Angle Measurement

The sliding angle measures the angle at which a liquid film slides over a solid surface. It is commonly employed to assess the slip resistance of a surface.

sliding angle 1

Sample Image taken from Droplet Lab Tensiometer

Learn how Sliding Angle measurement is done on our Tensiometer

For a more complete understanding of Sliding Angle measurement, read our Sliding Angle Measurement: The Definitive Guide

Sliding Angle Measurement: The Definitive Guide

Chapter 6: Real-World Applications

Within the Medical Device industry, several case studies exemplify the advantages of conducting surface property measurements.

Engineered Detection Zone to Enhance Color Uniformity on Paper Microfluidics Fabricated via Parafilm-Heating-Laser-Cutting

The authors introduce a simple, high-resolution fabrication approach for Parafilm®-laminated µPADs using a three-step Parafilm®-heating-laser-cutting workflow (laminate Parafilm® onto paper via oven heating, then pattern using CO₂ laser ablation). They also present engineered detection-zone geometries (multi-inlet and segmented designs) that significantly improve color uniformity in a model enzymatic glucose colorimetric assay, without chemically modifying the paper. They demonstrate improved gradient reduction, strong calibration in artificial urine across clinically relevant glucose ranges, and successful testing of spiked real human urine samples.

Role of the Droplet Lab Goniometer

A Droplet Lab Dropometer was used to measure water contact angle to confirm that the hydrophobicity of the Parafilm® layer remained essentially unchanged after the laser ablation step (i.e., the fabrication process did not degrade the barrier’s wettability performance). Specifically:

  • In Methods (Device characterization), the paper states that water contact angle of pristine Parafilm® and the Parafilm® layer after laser ablation of paper was assessed using Dropometer (Droplet Lab).

In Results, they report contact angles of ~108° (pristine) vs ~109° (post-ablation), supporting that the PHLC process preserved Parafilm® hydrophobic behavior critical for reliable microfluidic containment.

Key Findings

  • High-resolution laminated µPAD fabrication was achieved with a minimum barrier width of 172 ± 15 µm, enabling compact designs.
  • Engineered detection zones (multi-inlet and segmented) reduced color gradient in the glucose assay from 28.77% (conventional) to 12.35% (multi-inlet) and 8.95% (segmented).
  • The segmented D-zone was selected for analytical validation due to best uniformity and reproducibility.
  • In artificial urine, glucose detection showed excellent curve fits (R² > 0.99) across 2-50 mM, with a reported LOD ~1.65 mM (linear region).
  • Spiked real urine tests (5.5, 7.5, 9.5 mM) produced recoveries roughly ~92-111% with strong precision (reported RSDs <3% for those replicates).

Why it matters

For medical-device-style paper diagnostics, non-uniform color development is a major source of readout variability (especially for phone-camera or visual interpretation). This work shows that geometry alone (engineered detection-zone inlets/segmentation) can substantially improve signal homogeneity, which supports more reliable semi-quantitative interpretation, stronger QC tolerances, and more reproducible manufacturing, without adding chemical surface treatments that complicate scale-up.

Method Snapshot

  • Surface/solid tested (for Droplet Lab measurement): pristine Parafilm® sheet and Parafilm® layer after paper was laser-ablated (exposed Parafilm® region)
  • Droplet: water (reported as water contact angle testing; droplet volume not specified)
  • Temperature: not explicitly stated for contact-angle measurement (device testing commonly at room temperature)
  • Angle type: reported as water contact angle (consistent with static contact angle reporting; advancing/receding not reported)
  • Surface tension: not measured/reported in this study for the contact-angle experiment (water used as the probe liquid)

Data Note

    • Figure 3A (page showing Fig. 3) reports the water contact angle measured using the Droplet Lab Dropometer, comparing pristine Parafilm® (108 ± 5°) vs post-laser-ablation Parafilm® (109 ± 5°).
Figure

Citation (APA Format)

Safiabadi Tali, S. H., Hajimiri, H., Sadiq, Z., & Jahanshahi-Anbuhi, S. (2023). Engineered detection zone to enhance color uniformity on paper microfluidics fabricated via Parafilm®-heating-laser-cutting. Sensors and Actuators B: Chemical, 380, 133324. https://doi.org/10.1016/j.snb.2023.133324

View Publication →

Implant surfaces and cleaning

Implant surfaces are blasted, etched, cleaned and sometimes plasma treated, and each step changes wetting. Water or saline contact angle on a test disc tracks each change.

A Harvard School of Dental Medicine team measured saline contact angle before and after plasma treatment of titanium discs. A University of Manchester study used the Dropometer to show how rotary brushes changed titanium implant surfaces. Our dental and orthopedic implant surface QC page sets out the test plan.

Implant surfaces and cleaning

Drug releasing coatings on catheters

Coatings that release drugs or antimicrobial peptides change the catheter surface they sit on. Water contact angle on cut catheter pieces checks that each coating went on as designed.

A group at Universidad Católica de Temuco measured silicone Foley catheters before and after coating. Its silver layer by layer coating with ciprofloxacin and its graphene oxide and PEI coatings for antimicrobial peptides both lowered the contact angle.

Drug releasing coatings on catheters

Biodegradable materials and hydrogels for healing

Hydrogels and biodegradable scaffolds must hold water and let cells attach, so wetting is part of their design. Contact angle on a swollen hydrogel surface is a quick check between formulations.

Researchers measured water contact angle on bio adhesive GelTA hydrogels for muscle regeneration and reported values around 50 to 70 degrees. Our hydrogel and biomaterial wettability page covers sample handling. The Harvard shared facility measures hydrogels on the same instrument as titanium and films.

Biodegradable materials and hydrogels for healing

We are your partners in solving your Business & Technological challenges

If you are interested in implementing these or any other applications, please contact us.

Contact Us

Chapter 7: Standards and Guidelines

In an industry where precision reigns supreme, how can Medical Device manufacturers ensure their products withstand scrutiny? The answer lies in standards and guidelines: the compass that guides them through the complex maze of quality and performance.

FDA 510(k) Guidance, Contact Lens Care Products (Chemistry Appendix B): Determination of Critical Micelle Concentration (CMC) by Surface Tension

What it is

FDA-described approach to estimate a surfactant (or surfactant system) CMC by measuring surface tension (γ) across a dilution series prepared in the product/device medium, plotting γ vs log(concentration), and determining the breakpoint via least‑squares linear regression. It is intended to support defensible selection and documentation of surfactant concentration for contact lens care products with cleaning claims.

When to use it

510(k) support for cleaners with surfactants

Use when you need to show the surfactant level is selected with reference to CMC in the actual product medium (not pure water).

In-house formulation/QC control

Use to trend lot-to-lot or batch-to-batch behavior by comparing full γ vs log(C) curves and breakpoint stability over time.

In-scope / Out-of-scope

In scope
  • Preparing a device/product-medium dilution series (medium without surfactants + surfactant system at product ratio, then dilutions).
  • Surface tension measurement at each concentration using a tensiometer (geometry not specified by the guidance).
  • γ vs log(concentration) plotting and least‑squares regression to estimate the CMC breakpoint.
  • Controlling and documenting temperature and medium conditions (e.g., pH/tonicity/inactives) because they materially affect CMC.
Out of scope
  • Mandating a specific tensiometer geometry (ring/plate vs pendant drop equivalence is your validation responsibility).
  • Demonstrating cleaning effectiveness directly (CMC is a supporting characterization metric, not a cleaning test by itself).
  • Comparing CMC values across different media when pH/tonicity/inactives are not controlled and documented.
  • Claims of electronic record compliance / submission acceptability without site validation and quality-system controls.

Minimum you must report (checklist)

  • Solution 1: product/device medium without surfactants (include pH, tonicity, and other relevant inactives).
  • Solution 2: surfactant system identity and ratio(s) (if multiple surfactants) plus starting concentration.
  • Solution 3: dilution series concentrations (explicit list) and preparation scheme (volumes/dilution factor) with lot IDs where applicable.
  • Measurement conditions: temperature setpoint and actual temperature (per point or per run), plus any required inputs (e.g., density if needed for your method).
  • Instrument/method: tensiometer type/geometry (e.g., pendant drop) and key acquisition settings (including any dwell/equilibration time).
  • Data quality rules: fit/acceptance criteria and any re-run rules (e.g., unstable drop, poor fit, out-of-spec temperature).
  • Results table: γ at each concentration with replicates and summary statistic (e.g., mean ± SD) and the number of replicates.
  • Analysis outputs: γ vs log(C) plot, regression approach/ranges used, and the estimated CMC (breakpoint concentration) with units (and uncertainty if required by SOP).

FDA guidance describes an approach; defensibility comes from executing it consistently and documenting method validation, controls, and traceable records under your quality system. Tools like Dropometer can support this workflow by generating a traceable γ vs log(C) dataset and breakpoint fit, but the implementation must be validated and governed by your site controls.

How to interpret results (guardrails)

  • Pre‑CMC vs post‑CMC behavior: expect a decreasing γ region (adsorption) followed by a plateau; the CMC is the regression breakpoint between these regions.
  • Only compare like-with-like: CMC shifts with temperature and medium composition, do not compare runs unless pH/tonicity/inactives and temperature are controlled and recorded.
  • Set internal margins and limits: use the CMC estimate to define product-specific targets (e.g., “surfactant concentration ≥ X× CMC in product medium”) based on your performance/QC evidence.
  • Reject bad points, not just bad curves: rerun concentration points that fail fit/QC gates or input limits, and ensure regression ranges reflect true linear/plateau regions rather than noise.
Read our FDA 510(k) Guidance, Contact Lens Care Products page

Now It’s Your Turn

We hope this guide showed you how to apply surface science in the Medical Device industry.

Now we’d like to turn it over to you: 

  • What’s the #1 real-world application from this post that you want to try first?
  • Perhaps we missed a relevant industry standard.
  • Or maybe you have a question about something you read.

Feel free to leave a comment below—we’d love to hear from you.

Frequently asked questions

Which surface measurement should a medical device team start with?

Start with the step that most often goes wrong. Use water contact angle to check plasma treatment, cleaning and coatings on implants, catheters and tubing. Use surface free energy, worked out from contact angles of two or more probe liquids, when adhesives or inks must bond. Use surface tension for cleaning and lens care solutions. Our contact angle guide explains the method.

Which standards or guidance cover surface tension and wetting for medical devices?

The FDA 510(k) guidance for contact lens care products describes finding the critical micelle concentration from surface tension across a dilution series. It does not set the instrument geometry, so the method is part of your validation. The Dropometer uses the pendant drop method for surface tension and the sessile drop method for contact angle. Contact angle limits for coatings are usually set in your own specification.

Can contact angle be measured on catheters and tubing?

Yes, with a holder that keeps the curved surface level under the drop. The Temuco group measured cut pieces of 14Fr and 20Fr silicone Foley catheters. Zeus uses a custom 3D printed tube holder for its polymer tubing. Zeus ran its own Gage R&R on the Dropometer and it passed. Our catheter coating page covers the setup.

How do I check that plasma treatment worked?

Measure water contact angle on a treated part and an untreated control, and record the time since treatment. A lower angle shows the surface became more wettable. In the Harvard School of Dental Medicine study, saline contact angle on rough titanium fell from 77.3 to 15.7 degrees after plasma. Repeat the check over time to see how long the effect lasts. See plasma treatment verification.

Does contact angle predict how cells or bacteria respond?

Not on its own. Contact angle shows that the surface changed, and you link that to biology in your own tests. A University of Maryland study found the lower contact angle coatings for provisional crowns suppressed biofilm most, but credited the antibacterial agent. The Manchester implant study said the effect of wettability on healing is unclear.

Can I use contact angle for paper and lateral flow diagnostics?

Yes. Contact angle shows how the hydrophobic barrier and the paper channel wet, which controls how a sample wicks. A Concordia University team measured Parafilm barriers before and after laser cutting. See its engineered detection zone study and its doctoral thesis on portable sensors. See lateral flow wicking control.

Can I check our in house contact angle setup against the Dropometer?

Yes. A University of Saskatchewan team checked its home built apparatus against a Dropometer reading on PTFE film. It then measured carbon nitride films for protein adsorption on its own rig. Its PTFE result fell within the Dropometer range. Use a stable reference film like PTFE and run both setups on the same sample.

How accurate is the Dropometer?

The drop shape method was validated against a KRUSS DSA100E in two peer reviewed papers, one in Review of Scientific Instruments and one in Colloids and Surfaces A. Published contact angle accuracy is 0.35 degrees. Automatic edge and baseline detection gives the same reading from the same image. See our validation papers.

Standards, evidence and resources

1. Industry standards
  • FDA 510(k) guidance: CMC by surface tension: For contact lens care products, the guidance finds critical micelle concentration from surface tension across a dilution series in the cleaner medium, a step the Dropometer runs by pendant drop.
Use cases
  • Plasma treatment verification for adhesion: Water contact angle on treated parts and untreated controls confirms plasma reached each catheter, housing or implant surface and shows how fast the effect fades before bonding or coating.
  • Silicone and invisible residue detection: Contact angle screens device parts for silicone oil, lubricant and release agent films before bonding or coating, with FTIR or XPS used to confirm what the residue is.
  • Surface cleanliness verification: Water contact angle at fixed spots shows whether cleaning removed organic films from implants and device components, a quick numeric check beside validated cleaning tests.
  • Catheter and medical device hydrophilic coating checks: Water contact angle on coated catheter sections shows whether a coating cured and covered evenly, as an in process control alongside drag force lubricity tests.
  • Dental and orthopedic implant surface QC: Water contact angle tracks how blasting, etching, cleaning, plasma and ageing change titanium implant wettability, so teams build their own reference values for each surface finish.
  • Anti fog coating validation: A very low water contact angle shows an anti fog coating still spreads condensation into a clear film after cleaning and ageing, useful for healthcare eyewear and face shields.
  • Hydrogel and biomaterial wettability: Water contact angle on swollen hydrogels and scaffolds compares formulations meant for cell attachment, a quick check between batches since no standard sets a hydrogel contact angle.
  • Paper microfluidic and lateral flow wicking control: Contact angle on hydrophobic barriers and paper channels shows how a sample will wick, helping diagnostics teams trace flow time variation in lateral flow and paper assays.
Case studies Client citations (our analysis of each paper) Use case collections Further resources