Hierarchical Surface Restructuring

HSR™

X-ray computed tomography (X-ray CT) image of a 16-channel spinal cord stimulation (SCS) microelectrode array.

Redefine Implantable Electrode Performance

As implantable neural and cardiac interfacing devices shrink and grow more complex, performance often suffers. Impedance rises, stimulation efficiency diminishes, signal fidelity degrades, and coatings—while sometimes helpful—can introduce new challenges.

Meet Hierarchical Surface Restructuring (HSR™) technology, Pulse Technologies’ foundational surface engineering platform.

It restructures the native electrode surface across nano, micro, and macro scales to enhance electrochemical performance and long-term stability, without altering the chemical integrity of materials like Pt–10%Ir.

Smaller Electrodes.
Higher-Fidelity Signals.
No Coatings Required.

HSR™ uses ultrashort pulse lasers to restructure the surface of implantable electrodes, increasing electrochemically active surface area and boosting performance—no coatings required.

You can expect:

Deliberately engineered surface architecture that increases charge storage capacity and specific capacitance, and enhances charge exchange efficiency across all active dimensions
Tunable electrochemical properties with the ability to adjust surface hierarchy and topography via laser parameters
Scalable, in-line manufacturing compatibility using commercially viable, cost-effective technology
Designed to support miniaturized, high-density electrode arrays through integration of a large number of electrodes that promote enhanced performance, selectivity, fidelity, and lower power consumption
Consistent and enhanced electrochemical performance, which directly impacts stimulation efficiency, sensing fidelity, and long-term reliability
Enhanced durability with no adhesion or delamination concerns from secondary coatings

3D CONFOCAL MAPS

Select 3D confocal maps of hierarchically restructured surfaces of Pt-10Ir electrodes.

Focused Ion Beam

Focused ion beam (FIB) cross sections of hierarchically restructured Pt-10Ir alloy electrodes restructured at 4.10 J/cm2 fluence (a and b) and 1.98 W average power (c); red dashed arrows show subsurface features likely attributed to laser shock waves.

SEM Micrographs

SEM micrographs of hierarchically restructured electrodes for various neural interfacing applications: a) a cylindrical, and, b) a helix Pt-10Ir electrode for cardiac rhythm management applications; c) a rivet-style Pt-10Ir electrode for an electrophysiology mapping catheter and, d) a cylindrical Pt-10Ir electrode for use in a percutaneous spinal cord stimulation electrode array.

SEM Micrographs

SEM micrographs of the hierarchical surface structure induced on the surface of a Pt-10Ir alloy electrode used for a paddle-lead spinal cord stimulation electrode array.

Representative Scanning Electron Microscope

Representative scanning electron microscope.

If you just shrink the electrode, performance drops. HSR™ technology changes the surface so performance can improve as the electrode’s geometric size decreases.

This holds true even on complex 3D geometries—like cylinders, domes, helices, and other non-planar shapes—where uniform surface restructuring ensures consistently enhanced electrochemical performance.

By enabling line-of-sight treatment across these challenging contours, HSR™ supports improved stimulation efficiency and sensing fidelity at the electrode-tissue interface while simplifying manufacturing.

SEM Micrographs - Hierarchical Surface Restructuring

Unlock Next-Generation Performance with Laser Precision

HSR™ enables over two-orders-of-magnitude improvement in charge storage capacity and over 700-fold increase in specific capacitance compared to untreated electrodes.

These gains support both recording and stimulation functions in implantable neural interfacing applications while simplifying manufacturing by eliminating costly vacuum and batch processes.

Discover the HSR™ Difference

Focused ion beam cross-sectional analysis reveals subsurface features created during the laser restructuring process.

These features, along with increased surface roughness, are believed to drive the enhanced electrochemical performance observed in HSR™-treated electrodes.

Unlike traditional coating-based enhancements that introduce new interfaces prone to mechanical failure or chemical degradation, HSR™ restructures the electrode itself. This not only eliminates coating-related failure modes, it also alters the degradation mechanisms—demonstrating improved durability relative to coating-based approaches under extended electrical stimulation.

Hierarchical architecture. Designed with purpose:

Nanoscale features expand electrochemically active surface area, boosting charge storage capacity and interfacial capacitance
Microscale features facilitate ion transport and efficient charge transfer
Macroscale topography preserves geometric integrity and ensures uniform treatment across complex electrode shapes

IMPEDANCE MAGNITUDE

a) Impedance magnitude as a function of frequency (plotted in the 0.1-105 Hz frequency range) for a pristine unrestructured Pt-10Ir electrode, and select hierarchically restructured electrodes as a function of average power (only those electrodes restructured at 0.61, 1.52 and 3.35 W are shown for simplicity), b) Impedance magnitude as a function of frequency (plotted in the 0.1-10 Hz frequency range) for a 4 µm thick TiN coated Pt-10Ir electrode and a pristine Pt-10Ir electrode for comparison with the restructured electrode at 0.61 W, and, c) Impedance magnitude as a function of frequency (plotted in the 0.1-10 Hz frequency range) for the 4 µm thick TiN coated Pt-10Ir electrode and the Pt-10Ir electrode restructured at 3.35 W.

CYCLIC VOLTAMMOGRAM

Cyclic voltammograms of, a) a series of electrodes restructured under varying restructuring conditions (0.61 to 3.35 W) and a pristine un-restructured Pt-10Ir electrode (inset), and, b) a 4 µm thick TiN coating for comparison with an electrode restructured at 3.35 W, and a pristine Pt-10Ir electrode; noteworthy is the two orders of magnitude increase in CSCtotal for the electrode restructured at 3.35 W average power compared to its un-restructured counterpart.

CONFOCAL MAPS

Representative 2D (top row), 1D (middle row), and 3D (bottom row) confocal maps of hierarchically restructured surfaces of Pt-10Ir electrodes at 0.61, 1.98, and 3.35 W Average Power. Note that the cross-sectional profile (1D confocal map) is obtained at the center of the map along the horizontal direction.

CONFOCAL MAPS

Representative 2D (top row), 1D (middle row), and 3D (bottom row) confocal maps of hierarchically restructured surfaces of Pt-10Ir electrodes at 12.30, 4.10, and 2.46 J/cm2 Fluence. Note that the cross-sectional profile (1D confocal map) is obtained at the center of the map along horizontal direction.

HIERARCHICALLY STRUCTURED SURFACE SCHEMATIC

Schematic of a hierarchically structured surface consisting of topographic features spanning a variety of length scales. For most applications, these varying length scales are the coarse-scale rough structures (~1-100 µm) and a finer structure subset (~5-100 nm) on top of the coarse structures.

Together, these interlocking length-scales deliver performance gains that cannot be achieved through conventional surface roughening or coating techniques—making HSR™ a true paradigm shift in implantable electrode design.

Drive Real-World Impact

HSR™ supports the development of long-term implantable devices across cardiac and neuromodulation applications, as well as retinal prosthesis and cochlear implants. Its tunable electrochemical properties help engineers design smarter, more responsive neural interfaces without the risks of traditional coatings.

As the core of Pulse’s surface engineering platform, HSR™ also supports future innovations such as Reactive-HSR™, Ultrathin-HSR™, and Antibacterial-HSR™ platforms, offering a stable, extensible foundation for next-generation devices ready for commercial scale and clinical impact.

Successful Biocompatibility Testing with HSR™

HSRTM has successfully cleared all biocompatibility testing with both platinum and titanium electrodes. Biocompatibility was evaluated by performing comprehensive cytotoxicity, sensitization, and irritation testing. Testing was performed at an independent lab in the United States that is accredited under the recognized international standard ISO/IEC 17025:2017

Experience our HSR™️ Surfaces Interactively

Ready to build the next generation of implantable performance?

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Recent News & Blogs on HSR™

Femtosecond laser hierarchical surface restructuring for next generation neural interfacing electrodes and microelectrode arrays

Sep 16, 2022

Shahram Amini, Wesley Seche, Nicholas May, Hongbin Choi, Pouya Tavousi & Sina Shahbazmohamadi Long-term implantable neural interfacing devices are able to diagnose, monitor, and treat many cardiac, neurological, retinal and hearing disorders through nerve...

Pulse Technologies Announces Successful Biocompatibility Results For Novel HSR™ Platinum-Iridium Electrode Surface Treatment Technology

Aug 1, 2022

Biocompatibility studies were conducted by an independent, certified lab based in the US in accordance with FDA and ISO standards.

Surface Treatment Technology Using Ultrashort Pulse Lasers Could Help Treat Heart Failure

Jul 8, 2022

Hierarchical Surface Restructuring technology can be used to enhance charge storage capacity, increase specific capacitance, & decrease impedance of electrodes & microelectrodes.

Pulse Technologies’ Electrode Surface Treatment Chosen for Cardiac Device

May 26, 2022

Pulse Technologies’ HSR™ electrode surface treatment is now part of Cardionomic’s Cardiac Pulmonary Nerve Stimulation (CPNS) System for treating heart failure.

Hierarchically Restructured Titanium Electrodes: A Novel, Low-Cost, High-Performing Platform for Leadless Pacemakers

Sep 9, 2021

Pulse’s hierarchical titanium surface restructuring is well-suited for enhancing titanium electrodes of leadless pacemakers.

How Pulse’s Newly Patented Hierarchical Surface Restructuring (HSR™) Technology Improves Electrode Performance in Implantable and Diagnostic Medical Devices

Aug 13, 2021

This blog post outlines how Pulse’s patented HSR™ technology can enhance the electrochemical performance of electrodes and microelectrode arrays via enhancements in their surface topology and surface characteristics.

Video Explains the Benefits of Hierarchical Surface Restructuring

Jun 22, 2021

This video, Hierarchical Surface Restructuring for Electrodes And Microelectrode Arrays, will introduce you to a unique technology that uses lasers to rearrange the molecular surface of electrode materials and promises to enhance the performance of next-generation sensing, recording and stimulating devices.

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