A group of researchers has developed a simple, lightweight, compact, and inexpensive microscope with a standard mobile phone, opening the door for applications in the field of basic medical diagnosis.
A small digital microscope with a cost a few dollars may be connected to a normal mobile phone camera and perform a basic medical diagnostics that would otherwise require expensive laboratory equipment. The microscope, which has no lens, allows a savings in weight and cost of using algorithms to extrapolate more information from the captured images. The device can for example be used to measure the amount of white an red blood cells, to detect the presence of diseased cells, to detect the presence of bacteria, all looking for simple images sent via a USB cable to a mobile phone equipped with an appropriate software to process the acquired data. The latest version of the microscope incorporates a method based on interference contrast to provide best quality images, in addition to diagnostic information.
Dispositivi come questo potrebbero rendere disponibili degli strumenti diagnostici alle popolazione che vivono in parti del mondo in cui la telefonia mobile è presente, ma l'accesso alle costose apparecchiature diagnostiche è consentito solo a pochi privilegiati (o, al limite, a nessuno).
Devices like this could make diagnostic tools available to people living in parts of the world where the mobile telephony is present, but access to expensive diagnostic equipment is permitted only to few privileged people (or even to nobody).
The scope of this microscope is to be simple and inexpensiv,e and that's the reason why are not used expensive lenses, but rather it is used the processing power available on existing mobile phones to obtain diagnostic and medical information from the acquired images. The tool was developed by a group of researchers at the University of California, Los Anageles (UCLA) led by Aydogan Ozcan, professor of electrical engineering and biomedical research.
The device consists of only two hardware components: a LED to illuminate the sample and a light-sensitive chip, each with a cost a few cents. Samples of material to be tested is placed between the appropriate slides and then inserted into a drive located between the LED and the light sensor (see 'b' image below). The dimensions are extremely compact (6cm x 4cm) with a weight of only 46 grams.
Since it does not use lenses, the microscope does not magnify the image, but is still able to reach a resolution of less than 2 micrometers, obtaining images comparable to those produced by a microscope with a magnification of 40X. This is made possible by special image processing software algorithms. The research team has also developed a new version of this microscope that incorporates a "trick" to improve the optical contrast on conventional microscopes. The method, called differential interference contrast, uses a prism to split the light main beam into two other beams with different polarization before illuminating the sample, and a second prism to recombine the beams after passing through the sample.
By combining the two beams it is possible to produce an image with high contrast. The prism costs about 2$, mantaining the total costs of the microscope under 3$.
Lensless diagnostic imaging is a promising tool for applications in the field of telemedicine, since today most of modern mobile phones are provided with a built-in camera, and, with also a connection to the network, it is possible to send acquired images at a great distance, for a closer examination performed by qualified personnel.
However, for those users who do not have a camera on their phone, it is also available a stand-alone version of the lensless microscope, which only requires a USB connection for power and to transfer the captured images to a laptop or cell phone for later remote transmission.
With respect to the previous image, the lensless microscope consists of the following parts:
- 1 - light detector - the slide containing the test material (eg blood) can be placed in the drive, located above the camera which contains a computer chip sensitive to light. The processor inside the mobile phone then performs the appropriate image processing software
- 2 - light source - the black plastic tube contains filters for light and a LED powered directly from the phone battery, but does not contain any lens
- 3 - the image acquisition system can be removed for a more comfortable phone conversation, or replaced by another model more suitable for the specific application
Regarding the applications of this device, the first thing that comes to mind is that relating to medical centers for remote diagnosis, to diagnose anemia, cancer, and infectious diseases such as malaria.
Particularly interesting is also the following video on the device created by the research group led by Ozcan.