Nanostars push SERS sensing to new performance levels

Surface-enhanced Raman scattering (SERS) spectroscopy has become a powerful tool for ultrasensitive and rapid chemical analysis. Its effectiveness comes from how light interacts with tiny metallic structures, generating electromagnetic fields that dramatically strengthen the Raman signal. However, turning this principle into reliable and scalable sensing platforms has been a long-standing challenge, limiting wider use of SERS in medical diagnostics, environmental monitoring, and molecular biosensing (if you would like to learn more about the current challenges of taking SERS into real-world applications, you can also read a previous review article published by the group).

In a study led by Sara Abalde-Cela, INL researchers from the Diéguez group have developed a plasmonic substrate that notably improves the stability and reproducibility of SERS-based sensing. Their work, published in Advanced Optical Materials, introduces a fabrication approach that combines precision nanopatterning with controlled chemical growth.

The process begins with electron beam lithography to create highly regular nanodisk arrays. These disks are then transformed into nanostars with sharp tips capable of producing extremely strong electromagnetic fields, leading into “hot spots”.

“Compared to nanodisks, which produce weaker and more homogeneous field enhancements, the nanostars show highly localised electromagnetic intensification at their tips,” explains Sara Abalde-Cela. “Both simulations, run by Temple Douglas from Nieder group, and experimental SERS measurements confirmed this transformation and validated its impact on signal amplification.”

The method challenges the perception that top-down fabrication is too costly or impractical for wider use. By optimising exposure conditions and adopting the dots-on-the-fly strategy, implemented by Alexandre Chícharo (former INL researcher and MSCA recipient) and Jerôme Borme from Alpuim group, the team reduced fabrication time and cost while keeping nanoscale precision. This approach also enables fine control over particle spacing, shape and distribution – factors that are critical for obtaining strong and consistent SERS signals. The nanostar arrays show how carefully engineered geometry can translate directly into improved sensing performance.

The research study also demonstrates a clear pathway towards scalable and application-focused SERS platforms. INL researchers highlight future opportunities such as integrating surface functionalisation and combining this method with large-area lithography techniques, such as nanoimprint or deep-UV lithography, to further enhance manufacturing efficiency.

By uniting precision nanofabrication with controlled chemistry, the INL team lays the groundwork for reliable and high-performance SERS substrates, opening new possibilities for molecular detection across biomedical diagnostics, chemical analysis and optical sensing.

This research was carried out under the European Innovation Council-funded project BIOCELLPHE, the EU-funded project 3DSECRET, and the Health From Portugal initiative under the Portuguese Recovery and Resilience Plan.

Text by Catarina Moura
Photography by Gina Palha