Tag Archives: Derek Tseng

Wearable microscopes

It never occurred to me that someone might want a wearable microscope but, apparently, there is a need. A Sept. 27, 2016 news item on phys.org,

UCLA [University of California at Los Angeles] researchers working with a team at Verily Life Sciences have designed a mobile microscope that can detect and monitor fluorescent biomarkers inside the skin with a high level of sensitivity, an important tool in tracking various biochemical reactions for medical diagnostics and therapy.

A Sept. 26, 2016 UCLA news release by Meghan Steele Horan, which originated the news item, describes the work in more detail,

This new system weighs less than a one-tenth of a pound, making it small and light enough for a person to wear around their bicep, among other parts of their body. In the future, technology like this could be used for continuous patient monitoring at home or at point-of-care settings.

The research, which was published in the journal ACS Nano, was led by Aydogan Ozcan, UCLA’s Chancellor’s Professor of Electrical Engineering and Bioengineering and associate director of the California NanoSystems Institute and Vasiliki Demas of Verily Life Sciences (formerly Google Life Sciences).

Fluorescent biomarkers are routinely used for cancer detection and drug delivery and release among other medical therapies. Recently, biocompatible fluorescent dyes have emerged, creating new opportunities for noninvasive sensing and measuring of biomarkers through the skin.

However, detecting artificially added fluorescent objects under the skin is challenging. Collagen, melanin and other biological structures emit natural light in a process called autofluorescence. Various methods have been tried to investigate this problem using different sensing systems. Most are quite expensive and difficult to make small and cost-effective enough to be used in a wearable imaging system.

To test the mobile microscope, researchers first designed a tissue phantom — an artificially created material that mimics human skin optical properties, such as autofluorescence, absorption and scattering. The target fluorescent dye solution was injected into a micro-well with a volume of about one-hundredth of a microliter, thinner than a human hair, and subsequently implanted into the tissue phantom half a millimeter to 2 millimeters from the surface — which would be deep enough to reach blood and other tissue fluids in practice.

To measure the fluorescent dye, the wearable microscope created by Ozcan and his team used a laser to hit the skin at an angle. The fluorescent image at the surface of the skin was captured via the wearable microscope. The image was then uploaded to a computer where it was processed using a custom-designed algorithm, digitally separating the target fluorescent signal from the autofluorescence of the skin, at a very sensitive parts-per-billion level of detection.

“We can place various tiny bio-sensors inside the skin next to each other, and through our imaging system, we can tell them apart,” Ozcan said. “We can monitor all these embedded sensors inside the skin in parallel, even understand potential misalignments of the wearable imager and correct it to continuously quantify a panel of biomarkers.”

This computational imaging framework might also be used in the future to continuously monitor various chronic diseases through the skin using an implantable or injectable fluorescent dye.

Here’s a link to and a citation for the paper,

Quantitative Fluorescence Sensing Through Highly Autofluorescent, Scattering, and Absorbing Media Using Mobile Microscopy by Zoltán Göröcs, Yair Rivenson, Hatice Ceylan Koydemir, Derek Tseng, Tamara L. Troy, Vasiliki Demas, and Aydogan Ozcan. ACS Nano, 2016, 10 (9), pp 8989–8999 DOI: 10.1021/acsnano.6b05129 Publication Date (Web): September 13, 2016

Copyright © 2016 American Chemical Society

This paper is behind a paywall.

Looking at nanoparticles with your smartphone

Researcher Aydogan Ozcan and his team at the University of California at Los Angeles (UCLA) have developed a device which when attached to a smartphone allows the user to view viruses, bacteria, and/or nanoparticles. (Yikes, I understood nanoparticles were perceptible with haptic devices and that any work on developing optical capabilities was pretty rudimentary). From the UCLA Sept. 16, 2013 news release on EurekAlert,

Aydogan Ozcan, a professor of electrical engineering and bioengineering at the UCLA Henry Samueli School of Engineering and Applied Science, and his team 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.

“This cellphone-based imaging platform could be used for specific and sensitive 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,” Ozcan said. “These results also constitute the first time that single nanoparticles and viruses have been detected using a cellphone-based, field-portable imaging system.”

In the ACS [American Chemical Society]  Nano paper, Ozcan details a fluorescent microscope device fabricated by a 3-D printer that contains a color 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.

Using this device, which attaches directly to the camera module on a smartphone, Ozcan’s 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 nanometers; a human hair is roughly 100,000 nanometers thick.

In a separate experiment, Ozcan’s team also detected nanoparticles — specially marked fluorescent beads made of polystyrene — as small as 90-100 nanometers.

To verify these results, researchers in Ozcan’s lab used other imaging devices, including a scanning electron microscope and a photon-counting confocal microscope. These experiments confirmed the findings made using the new cellphone-based imaging device.

For some reason I’m completely gobsmacked by the notion that I could look at nanoparticles on a smartphone at sometime in the foreseeable future.

Here’s a citation and a link to the paper,

Fluorescent Imaging of Single Nanoparticles and Viruses on a Smart Phone by Qingshan Wei, Hangfei Qi, Wei Luo, Derek Tseng , So Jung Ki, Zhe Wan, Zoltán Göröcs, Laurent A. Bentolila, Ting-Ting Wu, Ren Sun, and Aydogan Ozcan. ACS Nano, Article ASAP DOI: 10.1021/nn4037706 Publication Date (Web): September 9, 2013
Copyright © 2013 American Chemical Society

This paper is behind a paywall. Ozcan’s work was last mentioned here in a Jan. 21, 2013 posting about self-assembling liquid lenses.