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Researchers from the University of Brighton have found that changing the surface pattern and scale of 3D printed electrodes can significantly influence how well gold nanoparticles deposit on them.
Led by Dr. Bhavik Anil Patel, the study also explores how effectively these electrodes perform in sensing applications. Published in Electrochimica Acta, the study focuses on electrodes made using Fused Filament Fabrication (FFF). In this case, the team used a conductive filament made from carbon black and polylactic acid (CB/PLA), purchased from UK-based supplier 3DFilaPrint and printed using a Flashforge Creator Pro 3D printer.
When CB/PLA is 3D printed, the resulting electrodes tend to have high contact resistance due to their composite nature. This limits how well they conduct electricity and affects their performance in electrochemical sensing.
A common way to enhance these electrodes is by depositing gold nanoparticles on their surface, which are known for their excellent conductivity, biocompatibility, and ability to bind with biological molecules. However, it had remained unclear how the shape and size of the surface features on these electrodes influenced the gold deposition and the final sensing results.
Geometry impacts nanoparticle spread and sensing ability
To investigate this, the researchers printed six different electrode designs, each with a distinct surface pattern: knurl, revolve, or straight, at either a small scale (0.8 mm) or large scale (1.6 mm). They then applied gold nanoparticles onto these surfaces using electrodeposition, a technique where an electric current is used to coat the surface with gold from a liquid solution.
Each design was carefully analyzed using multiple tools, including scanning electron microscopy to view the gold distribution, contact angle measurements to assess surface wettability, and electrochemical tests to evaluate sensing performance.
The study revealed that both the pattern and scale of the electrode surface played a decisive role in how gold nanoparticles settled across it. In particular, the large-scale knurl pattern encouraged dense gold buildup along its ridges and edges, which translated to stronger performance in sensing tests.
Meanwhile, the smaller-scale revolve and straight patterns led to a more uniform but thinner distribution of gold. Interestingly, in some designs, these smaller-scale patterns ultimately outperformed their larger counterparts once the gold was deposited. The results suggest that flatter surfaces may offer more even coverage, depending on the geometry of the pattern.
These trends were further supported by contact angle measurements. After gold deposition, most electrode surfaces became more hydrophilic, with contact angles dropping significantly in some cases, a change that typically enhances electrochemical activity. Electrochemical impedance spectroscopy confirmed this shift in performance, showing notable reductions in charge transfer resistance across the patterned electrodes, indicating improved conductivity.
To see how this translated into a practical setting, the researchers tested their top-performing design, the large-scale knurl electrode, for its ability to detect nitrite, a gut-related compound that plays a role in digestion and can indicate inflammation or disease.
Using fecal samples from mice of two different ages, the sensor successfully detected significantly lower nitrite levels in samples from 24-month-old mice compared to 12-month-old ones (p < 0.05), aligning with known age-related declines in nitric oxide production. This real-world validation underscored not just the technical success of the electrode but also its potential in health monitoring.
Taken together, the findings show that careful design of electrode surface features can offer precise control over gold nanoparticle deposition, directly enhancing a sensor’s sensitivity and reliability. They also potentially enable tailoring sensors for specific use cases, using accessible and affordable 3D printing methods.
3D printed electrodes for sensing devices
Advances in 3D printing are making it increasingly straightforward to produce highly precise electrodes for use in sensor applications.
Back in 2021, Massachusetts Institute of Technology (MIT) researchers developed a new method for 3D printing interactive objects using a single piece of metamaterial embedded with capacitive sensing electrodes. The design featured a grid of flexible cells alongside conductive shear cells that responded to physical deformation by altering the distance between conductive walls, allowing the structure to detect forces, movements, and rotations.
To streamline design, the team introduced MetaSense, a custom CAD tool that simulated deformations and automatically optimized sensor placement. This approach enabled rapid prototyping of custom input devices and opened possibilities for intelligent environments, such as posture-sensing furniture.
Additionally, researchers from Nanyang Technological University, the University of Chemistry and Technology Prague, and King Saud University designed 3D printed graphene/PLA electrodes to detect the mycotoxin zearalenone (ZEA) in food.
The electrodes were modeled in Autodesk Fusion 360, printed on a Prusa i3 MK3 using FDM, and chemically pre-treated with DMF to expose the conductive graphene layer. Compared to standard Ag/AgCl electrodes, the activated graphene sensors showed a strong linear response (r = 0.995) across ZEA concentrations from 10 to 300 µM. The team demonstrated a viable proof-of-concept for low-cost, 3D printed electrochemical food safety devices.
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Featured image shows design and images of patterned 3D printed CB/PLA electrodes with varying scales. Image via University of Brighton.
