Low-cost, smartphone-based spectrometer could tell you whether something is good to eat or not

Imagine knowing which berry or mushroom is safe to eat during a hike or swiftly detecting pathogens in a hospital setting that would traditionally require days to identify. Now, imagine all this, plus the identification and detection of drugs, chemicals, and biological molecules invisible to the human eye — all through a smartphone-based instrument,

Phone-based spectrometry

Dr. Peter Rentzepis, a professor in the Department of Electrical and Computer Engineering at Texas A&M University, has developed and patented a handheld system that works like a Raman spectrometer. A Raman spectrometer works by using a laser to interact with the molecular vibrations within a sample. When light from the laser hits the molecules, it scatters in various directions. Most of this light scatters elastically, meaning it retains the same energy. However, a small portion scatters inelastically, meaning it changes energy levels, and this is known as Raman scattering. The Raman spectrometer measures these shifts in energy to provide a molecular fingerprint of the substance.

The system integrates lenses, a diode laser, and a diffraction grating — a small, thin, square surface that scatters light. It uses a cell phone camera to record the Raman spectrum. And it uses the computer’s processing power to derive the chemical composition and molecular structure based on this spectrum. It’s small enough to put in your pocket, says Rentzepi, and particularly useful when large-scale spectrometers are unavailable or too expensive to use.

Traditional Raman spectrometers are expensive, costing thousands of dollars. In contrast, Rentzepis’ invention can be produced at a significantly lower cost and identifies materials quickly.

Simple to use

Using the device is straightforward. The smartphone is placed behind the transmission grating with the camera facing the grating. A laser shoots a beam into a sample of unknown material, such as a bacterium, on a slide. The camera records the spectrum. And, when paired with an appropriate phone application/database, this handheld instrument can enable rapid materials identification on-site.

The applications of the handheld Raman spectrometer are vast and varied. In the medical field, it could revolutionize diagnostics by allowing for rapid detection of pathogens at the point of care. This speed could be crucial in managing outbreaks and preventing the spread of infectious diseases. In environmental science, the device could be used to detect pollutants in water or soil quickly, facilitating faster responses to contamination events.

This capability could be particularly useful in disaster-stricken areas where quick identification of harmful substances is essential for mitigation efforts. You could even use it in the food industry to assess whether something is safe to eat or contains any contaminants. Farmers and foragers could use the device to identify plants and mushrooms, distinguishing between edible and toxic species, thereby preventing food poisoning.

A smartphone revolution

It seems crazy that we could soon have spectrometers in our very pockets. But, if we zoom out a bit, the development of this low-cost spectrometer is part of a broader trend of increasingly potent smartphone-based devices. As technology advances, the capability of smartphones extends far beyond communication, turning them into powerful tools for scientific analysis, health monitoring, and environmental sensing.

For instance, smartphone-based microscopes have been developed for diagnosing diseases in remote locations. These devices use the phone’s camera and additional lenses to magnify samples, allowing health workers to identify pathogens in blood or water samples without needing bulky laboratory equipment. Similarly, portable electrocardiogram (ECG) devices that connect to smartphones can monitor heart activity, sending data to doctors in real-time. This technology is particularly beneficial for patients in rural areas, providing critical health data without the need for frequent hospital visits.

Environmental monitoring has also seen innovations with smartphone-based devices. Portable air quality monitors that connect to smartphones can measure pollutants and provide real-time data on air quality, helping individuals with respiratory conditions manage their health more effectively. Several other types of smartphone-based spectrometers have also been developed by researchers.

However, several challenges remain. Ensuring the accuracy and reliability of these portable devices is crucial for their widespread adoption. Developing comprehensive databases for material identification and user-friendly interfaces for non-experts will also be essential in maximizing the potential of these devices. 

The invention has been patented and has not been published in a peer-reviewed journal.