Mobile phone scanner detects harmful bacteria

The scientists published their findings in the latest edition of the Royal Society of Chemistry journal Analyst.

Outbreaks of E. coli pose a huge threat to health, especially in developing countries. Most strains of E. coli are harmless but some strains however, such as enterohaemorrhagic E. coli (EHEC), can cause severe foodborne disease, according to the World Health Organisation. E. coli is transmitted to humans primarily through consumption of contaminated foods, such as raw or undercooked ground meat products, raw milk and contaminated raw vegetables and sprouts.

As existing detection devices are often expensive and complex, an accurate and efficient detection device could be extremely popular. There are more than five billion mobile phones on the planet and 70 per cent of these are in the developing world. 

Hongying Zhu and colleagues at the University of California, Los Angeles, developed a device able to take advantage of this technology. Zhu told the RSC's Chemistry World magazine: "Our cell phone based platform would be very useful to bring advanced technologies to remote and resource poor locations" adding that the phone provides "a ubiquitous platform for conducting advanced micro-analysis wherever cell phones work." 

The device consists of glass capillary tubes with light emitting diode (LED) lights on either end. E. coli antibodies are fixed to the sides of the capillaries and trap any E. coli present in a liquid sample. Secondary antibodies and quantum dots are then added to the capillaries and these bind to the trapped E. coli, capturing the bacteria in a sandwich complex. 

The LED lights excite the quantum dots, causing them to emit fluorescent light. The light emission is captured by the phone camera as pictures of the capillaries are taken approximately once a second.   

The team tested the device using water samples and milk and were able to selectively detect low concentrations of E. coli, even in the presence of other bacteria species. Zhu intends to develop the device so one phone could be used to detect different bacteria. 

More information: Quantum dot enabled detection of Escherichia coli using a cell-phone, H Zhu, U Sikora and A Ozcan, Analyst, 2012, DOI: 10.1039/c2an35071h

Provided by Royal Society of Chemistry

No extraordinary effects from microwave and mobile phone heating: Study quantifies effects of electric field-induced versus conventional heating

The effect of microwave heating and cell phone radiation on sample material is no different than a temperature increase, according to scientists from the Department of Chemistry and Biochemistry, Arizona State University, in Tempe, as published in a recent issue of the The European Physical Journal B.

Abidah Khalife, Ullas Pathak and Ranko Richert attempted for the first time to systematically quantify the difference between microwave-induced heating and conventional heating using a hotplate or an oil-bath, with thin liquid glycerol samples. The authors measured molecular mobility and reactivity changes induced by electric fields in these samples, which can be gauged by what is known as configurational temperature.

By conducting experiments at varying field frequencies and sample thicknesses, they realised that thin samples exposed to low-frequency electric field heating can have a considerably higher mobility and reactivity than samples exposed to standard heating, even if they are at the exact same sample temperature. They also found that at frequencies exceeding several megahertz and for samples thicker than one millimetre, the type of heating used does not have a significant impact on the level of molecular mobility and reactivity, which is mainly dependent on the sample temperature. In effect, the configurational temperatures will only be marginally higher than the real measurable temperature.

Previous studies were mostly fundamental in nature and did not establish a connection between microwaves and mobile phone heating effects. These findings imply that for heating with microwave or cell phone radiation operating in the gigahertz frequency range, no other effect than a temperature increase should be expected.

Since the results are based on averaged temperatures, future work will be required to quantify local overheating, which can, for example, occur in biological tissue subjected to a microwave field, and better assess the risks linked to using both microwaves and mobile phones.

Story Source:

The above story is reprinted from materials provided by Springer Science+Business Media.

Note: Materials may be edited for content and length. For further information, please contact the source cited above.

Journal Reference:

A. Khalife, U. Pathak, R. Richert. Heating liquid dielectrics by time dependent fields. The European Physical Journal B, 2011; 83 (4): 429 DOI: 10.1140/epjb/e2011-20599-5

Note: If no author is given, the source is cited instead.

Disclaimer: Views expressed in this article do not necessarily reflect those of ScienceDaily or its staff.

Phone losing charge? Novel technology allows LCDs to recycle energy

We've all worried about the charge on our smartphone or laptop running down when we have no access to an electrical outlet. But new technology developed by researchers at the UCLA Henry Samueli School of Engineering and Applied Science could finally help solve the problem.

The UCLA engineers have created a novel concept for harvesting and recycling energy for electronic devices — one that involves equipping these devices' LCD screens with built-in photovoltaic polarizers, allowing them to convert ambient light, sunlight and their own backlight into electricity.

LCDs, or liquid crystal displays, are used in many of today's electronic devices, including smartphones, TV screens, computer monitors, laptops and tablet computers. They work by using two polarized sheets that let only a certain amount of a device's backlight pass through. Tiny liquid crystal molecules are sandwiched between the two polarizers, and these crystals can be switched by tiny transistors to act as light valves. Manipulating each light valve, or pixel, lets a certain amount of the backlight escape; millions of pixels are combined to create images on LCDs.

The UCLA Engineering team created a new type of energy-harvesting polarizer for LCDs called a polarizing organic photovoltaic, which can potentially boost the function of an LCD by working simultaneously as a polarizer, a photovoltaic device and an ambient light or sunlight photovoltaic panel.

Their research findings are currently available in the online edition of the journal Advanced Materials and will be published in a forthcoming print issue of the journal.

"I believe this is a game-changer invention to improve the efficiency of LCD displays," said Yang Yang, a professor of materials science at UCLA Engineering and principal investigator on the research. "In addition, these polarizers can also be used as regular solar cells to harvest indoor or outdoor light. So next time you are on the beach, you could charge your iPhone via sunlight."

From the point of view of energy use, current LCD polarizers are inefficient, the researchers said. A device's backlight can consume 80 to 90 percent of the device's power. But as much as 75 percent of the light generated is lost through the polarizers. A polarizing organic photovoltaic LCD could recover much of that unused energy.

"In the near future, we would like to increase the efficiency of the polarizing organic photovoltaics, and eventually we hope to work with electronic manufacturers to integrate our technology into real products", Yang said. "We hope this energy-saving LCD will become a mainstream technology in displays."

"Our coating method is simple, and it can be applied in the future in large-area manufacturing processes," said Rui Zhu, a postdoctoral researcher at UCLA Engineering and the paper's lead author.

"The polarizing organic photovoltaic cell demonstrated by Professor Yang's research group can potentially harvest 75 percent of the wasted photons from LCD backlight and turn them back into electricity," said Youssry Boutros, program director for the Intel Labs Academic Research Office, which supported the research. "The strong collaboration between this group at UCLA Engineering and other top groups has led to higher cell efficiencies, increasing the potential for harvesting energy. This approach is interesting in its own right and at the same time synergetic with several other projects we are funding through the Intel Labs Academic Research Office."

More information: http://onlinelibra … 514/abstract

Provided by University of California Los Angeles (news : web)

Got flow cytometry? All you need is five bucks and a cell phone

Flow cytometry, a technique for counting and examining cells, bacteria and other microscopic particles, is used routinely in diagnosing disorders, infections and cancers and evaluating the progression of HIV and AIDS. But flow cytometers are big, bulky contraptions that cost tens of thousands of dollars, making them less than ideal for health care in the field or other settings where resources are limited.

Now imagine you could achieve the same results using a device that weighs about half an ounce and costs less than five dollars.

Researchers at the BioPhotonics Laboratory at the UCLA Henry Samueli School of Engineering and Applied Science have developed a compact, lightweight and cost-effective optofluidic platform that integrates imaging cytometry and florescent microscopy and can be attached to a cell phone. The resulting device can be used to rapidly image bodily fluids for cell counts or cell analysis.

The research, which was led by Aydogan Ozcan, a professor of electrical engineering and bioengineering and a member of the California NanoSystems Institute at UCLA, is currently available online in the journal Analytical Chemistry.

"In this work, we developed a cell phone–based imaging cytometry device with a very simple optical design, which is very cost-effective and easy to operate," said Hongying Zhu, a UCLA Engineering postdoctoral scholar at the BioPhotonics Lab and co-author of the research. "It has great potential to be used in resource-limited regions to help people there improve the quality of their health care."

The device is the latest advance by Ozcan's research team, which has developed a number of innovative, scaled-down, cell phone–based technologies that have the potential to transform global health care.

"We have more than 5 billion cell phone subscribers around the world today, and because of this, cell phones can now play a central role in telemedicine applications," Ozcan said. "Our research group has already created a very nice set of tools, including cell phone microscopes, that can potentially replace most of the advanced instruments used currently in laboratories."

How it works

Ozcan's group integrated compact optical attachments to create the optofluidic fluorescent cytometry platform. The platform, which weighs only 18 grams, includes:
1 simple lens (less than $3)
1 plastic color filter (less than $1)
2 LEDs (less than 30 cents each)
Simple batteries The microfluidic assembly is placed just above a separate, inexpensive lens that is put in contact with the cell phone's existing camera unit. This way, the entire cross-section of the microfluidic device can be mapped onto the phone's CMOS sensor-chip. The sample fluid is delivered continuously through a disposable microfluidic channel via a syringe pump.

The device is illuminated from the side by the LEDs using a simple butt-coupling technique. The excitation light is then guided within the cross-section of the device, uniformly exciting the specimens in the imaging fluid. The optofluidic pumping scheme also allows for the use of an inexpensive plastic absorption filter to create the dark-field background needed for fluorescent imaging.

In addition, video post-processing and contour-detection and tracking algorithms are used to count and label the cells or particles passing through the microfluidic chip.

In order to demonstrate proof-of-concept for the new platform, the team used the device to measure the density of white blood cells in human whole-blood samples, as white blood cell density is routinely tested to diagnosis various diseases and infections, including leukemia, HIV and bone marrow deficiencies.

"For the next step, we'd like to explore other potential applications of this device," Zhu said. "For example, we also want to utilize this device to count potential waterborne parasites for water-quality monitoring."

"We'd like to translate our devices for testing in the field and start using them in places they're supposed to be used," Ozcan said. "So I think the next stage for several of our technologies, including this one, is to deploy and test them in extremely poor-resource countries."

Provided by University of California - Los Angeles