Modern mobile phones come with high quality cameras. They detect even weak light and eliminate digital noise by processing captured images in software. This sensitivity of devices has been used to create cameras for mobile phones, which are already used as portable microscopes and heart rate sensors.
To turn an ordinary smartphone into a chemical detector, the scientists used fluorescence and Raman spectroscopy. The first method measures the fluorescent light emitted from the sample. The second is useful for detecting molecules such as DNA and RNA that do not fluoresce or emit very low intensity light.
The system includes an inexpensive diode laser as a light source oriented at right angles to the line connecting the sample and the cell phone camera. It is the right angle position that prevents reflected light from getting back into the camera.
Additional components, including a laser, add only $ 50 to the cost of a typical mobile phone. An inexpensive but accurate instrument suitable for detecting chemicals and pathogens in the field.