Chalmers miniaturizes biosensor for smaller and cost-effective devices

17 Mar 2026

Metasurface-based approach offers scalability for diverse applications and mass manufacture.

A project at Sweden's Chalmers University of Technology has developed a metasurface-enabled biosensor that could help move medical testing from hospitals to patients' homes.

Described in ACS Sensors the platform is a further sign of the transformative potential of metasurfaces in optics, noted the Chalmers team.

The device employs surface plasmon resonance (SPR), a phenomenon widely used in label-free biosensing. When a surface plasmon meets an analyte molecule, the resulting light emission can be highly sensitive to small concentrations of individual species, a valuable tool for biomarker detection.

But implementation of SPR has been largely restricted to high-end laboratories, due to the high costs and bulky nature of the instruments required.

Chalmers has now directly integrated the necessary optics and laser source for SPR onto a semiconductor chip, allowing for significantly more compact sensors. This could make optical biosensing technology portable, and applicable outside the laboratory environment.

"By successfully integrating the optics with the laser sources right on the chip, our innovation opens a lot of doors and is a key step towards shrinking the current biotech instruments and creating portable, battery-powered systems," commented Erik Strandberg of Chalmers.

"The chips we manufacture are about the size of a thumb tack and contain hundreds of lasers, each measuring 200 x 250 microns. Having both the laser and the optics integrated into the same semiconductor chip also enables cost-effective large-scale production of light sources for this technology."

Portable sensor for use outside the lab

In the Chalmers architecture, a metalaser array of VCSELs provides the illumination, with the sensing surface being a 50-nanometer gold film evaporated onto a glass block in a SPR-generating arrangement termed the Kretschmann configuration.

With both the coupling optics and the light source fabricated on one chip, surface plasmons can be excited in the metal film in a fully planar, miniaturized, and scalable solid-state SPR module, noted the Chalmers team in its paper. And thanks to the small size of the components, several independent SPR sensing channels can be realized with a single chip.

In trials using its new on-chip sensor, Chalmers demonstrated multiplexed detection of low-molecular-weight microRNA molecules with detection limits of 0.1 nanomoles per liter via direct sensing and 0.02 nM with antibody amplification. This is well within the clinically relevant range for microRNA biomarkers, according to the project.

The next steps will involve further developing the technology by boosting the sensitivity of the sensor, as well as increasing the number of samples that can be analyzed simultaneously.

"So far, we haven’t been able to use all the lasers on our chips to analyze samples, but this field offers great opportunities for further development," commented Hana Jungová from Chalmers.

"If we succeed, we believe the sensor will eventually make it possible to analyze significantly more samples at once than current technologies allow. But first, we plan to create a prototype of a portable sensor that can be used without extensive training. The ultimate goal is for hospitals and clinics to be able to use the sensor outside the lab."