Smartphone-based Raman spectrometer is cost-effectively convenient

Researchers at Texas A&M University (College Station, TX) took a significant step toward making advanced scientific tools more widely accessible by developing a smartphone-based Raman spectrometer system to detect and analyze chemicals, drugs, and other biological molecules and pathogens—invisible to the naked eye—by recording their Raman spectra (see video).

The portable setup is a less expensive alternative to conventional Raman spectroscopy systems, says Peter Rentzepis, a professor in the Department of Electrical and Computer Engineering at Texas A&M. He invented the system alongside former graduate students Dr. Dinesh Dhankhar, a system engineer at Thermo Fisher Scientific, and Anushka Nagpal, a process engineer at Intel Corp.; they now hold a patent for it.

“In Raman spectroscopy, a sample is irradiated with a laser light, which then emits Raman scattering that can be recorded and analyzed to identify the molecules’ composition,” Rentzepis explains. “But traditional Raman spectrometers are large, expensive, and primarily confined to laboratory use, and they require complex optics and high power. Our system was developed to use the advanced camera technology in modern smartphones, making Raman spectroscopy more compact, widely accessible, and cost-effective.”

How it works

Along with the smartphone camera technology, the setup incorporates lenses, a diode laser, and a diffraction grating to record the Raman spectrum. By placing a smartphone behind and facing the transmission grating, the laser shoots a beam into a sample of unknown material, such as bacteria, and the camera then records the spectrum. The system uses right-angle geometry, as well, to reduce noise and interference from Rayleigh scattering.

Peaks in the spectrum provide detailed data about a substance’s chemical composition and its molecular structure. The spectrometer system enables noninvasive detection and identification of potentially harmful chemicals or materials in the field, particularly in remote areas.

“Its portability makes it ideal for rapid, real-time detection in the field, where traditional laboratory equipment is not accessible,” Rentzepis says.

The technology is well suited for applications that require quick, onsite identification of substances, Rentzepis adds. This includes detecting contaminants in food, identifying drugs and chemicals, and analyzing biological samples such as bacteria or pigments—without sending samples to a laboratory.

What’s next?

While the system is already proving effective and accurate, there are challenges the researchers are working to overcome, Rentzepis points out. Most notably, the limited dynamic range of smartphone cameras and the need for further refinement in spectral resolution and noise reduction.

“The next steps for this technology involve further miniaturization, improving sensitivity and resolution, developing analysis software, and testing on more diverse and complex samples,” Rentzepis says.

The ultimate goal is to integrate this spectrometer system into future smartphones, making Raman spectroscopy a standard feature that can be used by anyone, anywhere, for a wide range of applications, from detecting pathogens in medical settings to identifying hazardous substances in situ in the environment. It also shows potential for use in forensics and consumer safety applications.

“This technology represents a significant step toward making advanced scientific tools accessible to the general public,” Rentzepis says. “This could make sophisticated analytical tools widely accessible, enabling more widespread and immediate in situ detection of substances in everyday life.”