A team of engineers at UCLA has created a 3D-printed attachment that enables smartphone cameras to image particles as small as 90 nanometers. This makes it the first portable, cellphone-based imaging system capable of detecting single nanoparticles and viruses according to the researchers.
The wavelength of light measures on the order of hundreds of nanometers. Imaging objects that are smaller ("sub-wavelength") is a challenge because the signal strength and contrast become very low.
Nonetheless, the team led by Prof. Aydogan Ozcan at UCLA managed to build a 3D-printed microscope attachment that can do just that.
The device uses a laser diode to illuminate samples at a steep angle of about 75 degrees, which prevents the lens from picking up most of the scattered light and increases the signal-to-noise ratio of the setup.
The scientists were able to use the device to detect single particles of the human cytomegalovirus (HCMV), a common virus that can cause birth defects, measuring 150 to 300 nanometers. In other experiments specially marked nanoparticles as small as 90-100 nanometers were detected. The results were later verified using a scanning electron microscope.
This development of this portable imaging system, which is said to weigh less than half a pound (0.23 kg) and should be cheap to manufacture, may prove beneficial for various point-of-care applications such as viral load measurements, or other biomedical tests conducted in remote or under-resourced areas.
A paper published on the journal ACS Nano (PDF) describes the device in detail.