Cell Phone Converted Into Powerful Chemical Detector for Just $50

Our cell phones come with high-quality cameras that can detect low levels of light and remove digital noise from captured images through software processing.

Scientists have utilized this sensitivity to create cell phone cameras that can act as microscopes in the past, and now, Texas A&M University researchers have created an extension for a standard smartphone that transforms it into a powerful chemical detector, according to a press release.

From an ordinary cell phone to a sophisticated scientific instrument, it can now detect chemicals, medicines, biological molecules, and pathogens.

But how?

The breakthrough, which is reported in Reviews of Scientific Instruments, was created using two kinds of spectroscopy (the study of the absorption and emission of light and other radiation by matter) methods: Fluorescence spectroscopy, which measures fluorescent light emitted by a sample, and Raman spectroscopy, which can detect molecules that do not fluoresce or emit light at extremely low intensities.

What's so great about this project is that it's budget-friendly. All the additional parts that will be mentioned cost just around $50 more than a normal smartphone. For example, the system has an inexpensive diode laser as a light source. The laser was focused at right angles to the line connecting the sample and the camera, with the arrangement successfully keeping back-reflected light out of the camera.

"In addition, this right-angle excitation geometry has the advantage of being easier to use for the analysis of samples where a bulk property is to be measured," explained author Peter Rentzepis.

The experiments

The scientists ran experiments in which they examined different samples such as ethanol, acetone, isopropyl alcohol, and methanol using the homemade cell phone detector. They also measured the Raman spectra of various solid materials, such as a carrot, which was picked thanks to its high concentration of pigment carotene, and a bacterial pellet. This pigment and bacteria pigments readily absorb the wavelength of the laser light used in the device.

When they compared the sensitivity of the system to the most sensitive industrial Raman spectrometers available, the researchers saw that the ratio of signal to noise for the commercial instrument was about 10 times higher than their system. 

The researchers note that the sensitivity of the cell phone detector could be doubled by making use of a single RGB channel for analysis. One drawback of the constructed cell phone detector is its relatively limited dynamic range, but this problem could be handled through a number of HDR (High Dynamic Range) applications that blend images from different exposures.

All in all, the scientists state that their device provides a reliable method for detecting chemicals and pathogens in the field, all the while being low-cost. While the researchers didn't say anything about detecting coronavirus, it certainly does remind us of this five cent sensor that detects coronavirus and immunity in just 10 minutes.