LONDON (TIP): Your smart phone may soon be able to double up as a high resolution microscope that can detect even the smallest virus. University of California Los Angeles researchers have created a portable smartphone attachment that can be used to perform sophisticated field testing to detect viruses and bacteria without the need for bulky and expensive microscopes and lab equipment. The device weighs less than half a pound. Using this device which attaches directly to the camera module on a smartphone the team was able to detect single Human Cytomegalovirus (HCMV) particles. HCMV is a common virus that can cause birth defects such as deafness and brain damage and can hasten the death of adults who have received organ implants who are infected with the HIV virus or whose immune systems otherwise have been weakened. A single HCMV particle measures about 150-300 nanometres – a human hair is roughly 100,000 nanometres thick.
Aydogan Ozcan, a professor of electrical engineering and bioengineering at the UCLA Henry Samueli School of Engineering and Applied Science said “This cell phonebased imaging platform could be used for detection of sub-wavelength objects, including bacteria and viruses and therefore could enable the practice of nanotechnology and biomedical testing in field settings and even in remote and resource-limited environments. These results also constitute the first time that single nanoparticles and viruses have been detected using a cell phone-based, field-portable imaging system”. In a separate experiment, Oscan’s team also detected nanoparticles — specially marked fluorescent beads made of polystyrene — as small as 90- 100 nanometres. To verify these results, researchers used other imaging devices, including a scanning electron microscope and a photon-counting confocal microscope. These experiments confirmed the findings made using the new cell phone-based imaging device. Capturing clear images of objects as tiny as a single virus or a nanoparticle is difficult because the optical signal strength and contrast are very low for objects that are smaller than the wavelength of light. Researchers here detail a fluorescent microscope device fabricated by a 3-D printer that contains a colour filter, an external lens and a laser diode. The diode illuminates fluid or solid samples at a steep angle of roughly 75 degrees. This oblique illumination avoids detection of scattered light that would otherwise interfere with the intended fluorescent image.