Modern cellphones include high-quality cameras capable of detecting low levels of light and eliminating digital noise through software processing of the captured images. Recent work has taken advantage of this sensitivity to produce cellphone cameras that can be used as portable microscopes and heart rate detectors.
Scientists from Texas A&M have developed an extension to an ordinary cellphone that turns it into an instrument capable of detecting chemicals, drugs, biological molecules, and pathogens. Researchers studied a variety of samples using their constructed cellphone 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 pellet of bacteria. The current advance is based on two types of spectroscopy, fluorescence and Raman. The system includes an inexpensive diode laser as a light source, oriented at right angles to the line connecting the sample and the cellphone camera. The right-angle arrangement prevents back reflected light from entering the camera. The study was published in the journal Review of Scientific Instruments.
"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," said study author Peter Rentzepis.
The additional components, including the laser, add a cost of only about $50 to the price of a typical cellphone, making this system an inexpensive but accurate tool for detecting drugs and pathogens in the field.
Photo: Photo showing relative size of spectrometer (left) and cellphone (right and at the lower end of the spectrometer). Credit: Peter Rentzepis