From hospitals into homes — could tiny biosensors transform medical sampling?

Swedish researchers have developed diminutive laser technology with the potential to move certain types of medical sampling out of hospitals into patients’ homes.

Laser technology that could lead to tiny, cost-effective biosensors has been developed by a team of researchers at Chalmers University of Technology in Sweden. Integrating lasers and optics together on a centimetre-sized chip, the researchers believe the sensors could free up hospital beds and reduce visits to clinics by moving testing from hospitals to patients’ homes.

Researchers can gain valuable insights by studying how various biomolecules interact with each other, for example antibodies in the immune system and xenobiotic antigens, leading to new medicines and vaccines — or assess whether a sample contains signs of infection. Based on a technique called surface-plasmon resonance, optical biosensors are a tool used for studying these types of interactions.

The sensors direct light onto a gold surface and measure minuscule changes in the light’s reflection when biomolecules are placed on the surface — the laser technology created by the Swedish researchers making it possible, they argue, to create such biosensors in a miniature format.

Opening the door to making optical sensing technology portable and applicable outside the laboratory environment, the laser source and the necessary optics are directly integrated onto a semiconductor chip, allowing for significantly more compact sensors. A study about the project was published open access in ACS Sensors (doi.org/10.1021/acssensors.5c01997).

“With this technology, we want to create an instrument that allows healthcare professionals to take certain samples in the patient’s home,” said the lead author of the study, Erik Strandberg — a doctoral candidate in photonics at Chalmers. “For example, we’re currently evaluating how well our sensor can perform a C-reactive protein (CRP) test.

“Because this technology is very general and can detect a wide range of biomolecular interactions, we see many potential applications for a wide variety of tests. This could allow patients to be discharged from hospital sooner after an operation — thereby freeing up hospital beds — and reduce the number of healthcare visits for sampling,” Strandberg said.

A precise laser beam must strike the gold surface at a steep angle to be able to monitor the interaction of biomolecules using an optical sensor; with extant solutions, the researchers said, requiring bulky optical components, such as prisms, which also make them time-consuming to install and align.

The sensor of the Swedish team consists of a one-centimetre chip fitted with hundreds of microscopic lasers, where the controlling optics to form exactly the right beam are integrated directly into the chip. This allows for a much smaller and lighter light source, the researchers said, which enables the creation of a compact sensor so small that it fits in the palm of your hand.

“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,” Strandberg added. “The chips we manufacture are about the size of a thumbtack and contain hundreds of lasers, each measuring 200x250 micrometres — few times thicker than a hair.

“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,” Strandberg said. Regarding the next steps towards the goal of this research, the team aims to further develop the technology by boosting the sensitivity of the sensor, as well as increasing the number of samples that can be analysed simultaneously.

Erik Strandberg, Chalmers University of Technology. Source: Chalmers University of Technology

Hana Jungová, Chalmers University of Technology. Credit: Chalmers University of Technology / Anna-Lena Lundqvist.

“So far, we haven’t been able to use all the lasers on our chips to analyse samples, but this field offers great opportunities for further development,” said senior researcher in the study Hana Jungová — a researcher in nano and biophysics at Chalmers. “If we succeed, we believe the sensor will eventually make it possible to analyse 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.”

Top image: A research team at Chalmers University of Technology has developed a new diminutive laser technology that makes it possible to create a miniature biosensor with the laser source and optics integrated onto a one-centimetre semiconductor chip. This enables significantly smaller sensors, paving the way for portable optical technology and for moving certain types of medical sampling from hospitals to the patients’ homes. Illustration credit: Erik Strandberg/Chalmers University of Technology.