From Mobile Phone To Chemical Detector

November 3, 2021

With only $ 50 worth of components, a typical mobile phone is transformed into a sophisticated scientific instrument, capable of identifying chemicals, drugs and pathogens.

Scientists at Texas A&M University have developed an extension of an ordinary mobile phone that makes it an instrument capable of detecting chemicals, drugs, biological molecules, and pathogens. The trailer is published in AIP Publishing’s Reviews of Scientific Instruments.

Modern mobile phones include high-quality cameras capable of detecting low light levels and eliminating digital noise through software processing of captured images. Recent work has taken advantage of this sensitivity to produce mobile phone cameras that can be used as handheld microscopes and heart rate detectors.

The current advance is based on two types of spectroscopy. One type, known as fluorescence spectroscopy, measures the fluorescent light emitted by a sample. Another, known as Raman spectroscopy, is useful for detecting molecules, such as DNA and RNA, that are not fluorescent or emit light at very low intensities. Both types were used to develop this mobile phone detector.

The system includes an inexpensive diode laser as a light source, oriented at right angles to the line connecting the sample and the camera of the mobile. The right angle arrangement prevents reflected light from entering the camera.

“In addition, this right-angle excitation geometry has the advantage of being easier to use for the analysis of samples in which a bulk property is to be measured,” says author Peter Rentzepis.

The researchers studied a variety of samples using their built cell detector, including common solvents such as ethanol, acetone, isopropyl alcohol, and methanol. They recorded the Raman spectra of solid objects, including a carrot and a granule of bacteria.

Carrots were chosen for this study because they contain the pigment carotene. The laser light used in your system has a wavelength that is easily absorbed by this orange pigment and the pigments of bacteria.

The researchers compared the sensitivity of their system with that of the most sensitive industrial Raman spectrometers available. The signal-to-noise ratio of the commercial instrument was about 10 times higher than that of the mobile system.

However, the sensitivity of the mobile phone detector could be doubled by using a single RGB channel for analysis. The system has a fairly limited dynamic range, but the researchers note that this problem can be easily overcome by various HDR, or high dynamic range, applications that combine images from multiple exposures.

The additional components, including the laser, add a cost of only about $ 50 to the price of a typical mobile phone, making this system an inexpensive but accurate tool for detecting chemicals and pathogens in the field.

Dr. Loony Davis5
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Born and raised in Brussels in an English family, I have always lived in a multicultural environment. After several work experiences in marketing and communication, I came to Smart Water Magazine, which I describe as the most exciting challenge of my career.
I am a person with great restlessness and curiosity to learn, discover what I do not know, as well as reinvent myself daily, someone who is curious about life and wants to know. I enjoy sharing knowledge.
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