Pencil-like spectrometer connects to smartphones for easy imaging

By Dave Muoio
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New research published the journal Biomedical Optics Express describes a smartphone-compatible spectrometer held and directed like a pencil. According to the article's authors, this novel device could be implemented at the point of care to diagnose medical conditions, while its ease of use and availability could greatly increase the generation of spectral image data for research projects.

Many optic applications involving smartphones have been presented previously and often rely on the built-in camera for imaging, the researchers explained in the research paper. However, this implementation can require additional tools that may come at the price of convenience.

"The easiest way to use a spectrometer is to wave it over the part of the body or object being examined," Fuhong Cai, of the department of electrical engineering at Hainan University, China, said in a statement. "However, many home-made portable spectrometers use a smartphone camera to acquire data and a phone cradle that contains other necessary optics. The cradle can be hard to align correctly and makes it awkward to wave the smartphone over the body."

Still, the processing power and easy operation of a smartphone makes it an appealing resource for point-of-care imaging. To leverage this, Cai and colleagues designed a novel prototype spectrometer consisting of commercial components available for less than $300. Users hold the device like a pencil and move it across target areas by hand, which builds up a series of spectral images that are transmitted wirelessly to a smartphone or other computer for reconstruction and viewing. A 16-second 3D spectral image data cube can also be constructed through manual scanning of the imaging spectrometer.

To gauge the device, the researchers conducted and reported successful optical sensing tests on bananas for ripeness, pork for myoglobin, and human hands for the monitoring of blood hemoglobin and regional differences in blood concentration. However, they wrote, there is still optimization to be done in terms of spectral resolution with the help of non-commercial materials. Further, they suspect that enhancing the device's sensitivity detector could allow the spectrometer to be used for fluorescent detection in bio-sensing.

Outside of point-of-care healthcare and food analysis, other potential uses for the device raised by the authors included improved ocean microorganism study, as well as large-scale data collection and analysis.

“Recently, machine-learning algorithms have been applied in the analysis of spectral data,” the researchers wrote. “As a combination of machine-learning algorithm and spectral image data cube, the present portable imaging spectrometer would find more interesting applications in the future."