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By using an “aluminum-doped zinc oxide,” or AZO, Purdue researchers have shown how to create metamaterials without using silver or gold. The new metamaterial consists of 16 layers alternating between AZO and zinc oxide and has enhanced performance that is compatible with semiconductors.

West Lafayette, Indiana – Researchers have taken a step toward overcoming a key obstacle in commercializing “hyperbolic metamaterials,” structures that could bring optical advances including ultrapowerful microscopes, computers and solar cells.

The researchers have shown how to create the metamaterials without the traditional silver or gold previously required, said Alexandra Boltasseva, a Purdue University assistant professor of electrical and computer engineering.

Using the metals is impractical for industry because of high cost and incompatibility with semiconductor manufacturing processes. The metals also do not transmit light efficiently, causing much of it to be lost. The Purdue researchers replaced the metals with an “aluminum-doped zinc oxide,” or AZO.

“This means we can have a completely new material platform for creating optical metamaterials, which offers important advantages,” Boltasseva said.

Doctoral student Gururaj V. Naik provided major contributions to the research, working with a team to develop a new metamaterial consisting of 16 layers alternating between AZO and zinc oxide. Light passing from the zinc oxide to the AZO layers encounters an “extreme anisotropy,” causing its dispersion to become “hyperbolic,” which dramatically changes the light’s behavior.

“The doped oxide brings not only enhanced performance but also is compatible with semiconductors,” Boltasseva said.

Research findings are detailed in a paper appearing Monday (May 14) in the Proceedings of the National Academy of Sciences.

The list of possible applications for metamaterials includes a “planar hyperlens” that could make optical microscopes 10 times more powerful and able to see objects as small as DNA; advanced sensors; more efficient solar collectors; quantum computing; and cloaking devices.

The AZO also makes it possible to “tune” the optical properties of metamaterials, an advance that could hasten their commercialization, Boltasseva said.

“It’s possible to adjust the optical properties in two ways,” she said. “You can vary the concentration of aluminum in the AZO during its formulation. You can also alter the optical properties in AZO by applying an electrical field to the fabricated metamaterial.”

This switching ability might usher in a new class of metamaterials that could be turned hyperbolic and non-hyperbolic at the flip of a switch.

“This could actually lead to a whole new family of devices that can be tuned or switched,” Boltasseva said. “AZO can go from dielectric to metallic. So at one specific wavelength, at one applied voltage, it can be metal and at another voltage it can be dielectric. This would lead to tremendous changes in functionality.”

The researchers “doped” zinc oxide with aluminum, meaning the zinc oxide is impregnated with aluminum atoms to alter the material’s optical properties. Doping the zinc oxide causes it to behave like a metal at certain wavelengths and like a dielectric at other wavelengths.

The material has been shown to work in the near-infrared range of the spectrum, which is essential for optical communications, and could allow researchers to harness “optical black holes” to create a new generation of light-harvesting devices for solar energy applications.

The PNAS paper was authored by Naik, Boltasseva, doctoral student Jingjing Liu, senior research scientist Alexander V. Kildishev, and Vladimir  mri remote monitoring  M. Shalaev, scientific director of nanophotonics at Purdue’s Birck Nanotechnology Center, a distinguished professor of electrical and computer engineering and a scientific adviser for the Russian Quantum Center.

Current optical technologies are limited because, for the efficient control of light, co Industrial 3g router  mponents cannot be smaller than the size of the wavelengths of light. Metamaterials are able to guide and control light on all scales, including the scale of nanometers, or billionths of a meter.

Unlike natural materials, metamaterials are able to reduce the “index of refraction” to less than one or less than zero. Refraction occurs as electromagnetic waves, including light, bend when passing from one material into another remote PLC programming  . It causes the bent-stick-in-water effect, which occurs when a stick placed in a glass of water appears bent when viewed from the outside. Each material has its own refraction index, which describes how much light will bend in that particular material and defines how much the speed of light slows down while passing through a material

Natural materials typically have refractive indices greater than one. Metamaterials, however, can make the index of refraction vary from zero to one, which possibly will enable applications including the hyperlens.

The layered metamaterial is a so-called plasmonic structure because it conducts clouds of electrons called “plasmons.”

“Alternative plasmonic materials such as AZO overcome the bottleneck created by conventional metals in the design of optical metamaterials and enable more efficient devices,” Boltasseva said. “We anticipate that the development of these new plasmonic materials and nanostructured material composites will lead to tremendous progress in the technology of optical metamaterials, enabling the full-scale development of this technology and uncovering many new physical phenomena.”

This work has been funded in part by the U.S. Office of Naval Research, National Science Foundation and Air Force Office of Scientific Research.

Image: Purdue University

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Cells pass through an sSMR device, which consists of multiple sensors that are fluidically connected in series and separated by delay channels (not all is shown). This design enables a stream of cells to flow through the device such that different sensors can concurrently weigh flowing cells in the stream.

Doctors have many drugs available to treat multiple myeloma, a type of blood cancer. However, there is no way to predict, by genetic markers or other means, how a patient will respond to a particular drug. This can lead to months of treatment with a drug that isn’t working.

Researchers at MIT have now shown that they can use a new type of measurement to predict how drugs will affect cancer cells taken from multiple-myeloma patients. Furthermore, they showed that their predictions correlated with how those patients actually fared when treated with those drugs.

This type of testing could help doctors predict drug responses based on measurements of cancer cell growth rates after drug exposure, says Scott Manalis, the Andrew and Erna Viterbi Professor in the MIT departments of Biological Engineering and Mechanical Engineering and a member of MIT’s Koch Institute for Integrative Cancer Research.

“For infectious diseases, antibiotic susceptibility testing based on cell proliferation has been extremely effective for many decades,” Manalis says. “Unlike bacteria, analogous tests for tumor cells have been challenging, in part because the cells don’t always proliferate upon removal from the patient. The measurement we developed doesn’t require proliferation.”

Manalis is the senior author of the study, which appears in the Nov. 20 issue ofNature Communications. The paper’s lead authors are Mark Stevens, a visiting scientist at the Koch Institute and research scientist at Dana-Farber Cancer Institute, and Arif Cetin, a former MIT postdoc.

An animation of how a serial suspended micro channel resonator functions with car router   cells flowing through the device. Cells pass over 10 cantilever mass sensors to have their mass weighed over a 15 minute interval, with measurements spaced by delay channels. Multiple measurements allow the researchers to capture changes in mass over time, a metric called mass accumulation rate (MAR).

Predicting response

The researchers’ new strategy is based on technology that Manalis and others in his lab have developed over the past several years to weigh cells. Their device, known as a suspended microchannel resonator (SMR), can measure cell masses 10 to 100 times more accurately than any other technique, allowing the researchers to precisely calculate growth rates of single cells over short periods of time.

The latest version of the device, which can measure 50 to 100 cells Industrial 3G Router   per hour, consists of a series of SMR sensors that weigh cells as they flow through tiny channels. Over a 20-minute period, each cell is weighed 10 times, which is enough to get an accurate MAR measurement.

A few years ago, Manalis and colleagues set out to adapt this technique to predict how cancer drugs affect tumor cell growth. They showed last year that the mass accumulation rate (MAR), a measurement of the rate at which the cells gain mass, can reveal drug susceptibility. A decrease in MAR following drug treatment means the cells are sensitive to the drug, but if they are resistant, there is no change in MAR.

In the new study, the researchers teamed up with Nikhil Munshi at Dana-Farber Cancer Institute to test a variety of drugs on tumor cells from multiple-myeloma patients. They then compared the results to what happened when the patients were treated with those drugs. For each patient, they tracked the cells’ response to three different drugs, plus several combinations of those drugs. They found that in all nine cases, their data matched the outcomes seen in patients, as measured by clinical protein biomarkers found in the bloodstream, which are used by doctors to determine whether a drug is killing the tumor cells.

“When the clinical biomarkers showed that the patients should be sensitive to a drug, we also saw sensitivity by our measurement. Whereas in cases where the patients were resistant, we saw that in the clinical biomarkers as well as our measurement,” Stevens says.

Personalized medicine

One of the difficulties in treating multiple myeloma is choosing among the many drugs available. Patients usually respond well to the f wireless networking  irst round of treatment but eventually relapse, at which point doctors must choose another drug. However, there is no way to predict which drug would be best for that particular patient at that time.

In one scenario, the researchers envision that their sensor would be used at the time of disease relapse, when the tumor may have developed resistance to specific therapies.

“At this time of relapse, we would take a bone marrow biopsy from a patient, and we would test each therapy individually or in combinations that are typically used in the clinic. At that point we’d be able to inform the clinician as to which therapy or combinations of therapies this patient seems to be most sensitive or most resistant to,” Stevens says.

The new test holds “great promise” to screen myeloma cells for drug susceptibility, says Kenneth Anderson, a professor of medicine at Harvard Medical School and Dana-Farber Cancer Institute, who was not involved in the research.

“This assay may fast-forward personalized medical care and the choice of effective therapies for myeloma both at diagnosis and at relapse,” Anderson says.“It may also be useful to profile susceptibility of minimal residual disease in order to further inform therapy and improve patient outcome.”

Bone marrow biopsies often produce limited numbers of tumor cells to test — as few as 50,000 tumor cells in this study — but for this technique that is enough to test many different drugs and drug combinations. The MIT researchers have started a company to begin a larger clinical study for validating this approach, and they plan to investigate the possibility of using this technology for other types of cancer.

The research was funded by the National Institutes of Health, the Koch Institute’s Cancer Center Support (core) Grant from the National Cancer Institute, the Department of Veterans Affairs, a Koch Institute Quinquennial Cancer Research Fellowship, and the Bridge Project of the Koch Institute and Dana-Farber/Harvard Cancer Center.

Publication: Arif E. Cetin, et al., “Determining therapeutic susceptibility in multiple myeloma by single-cell mass accumulation,” Nature Communications 8, Article number: 1613 (2017) doi:10.1038/s41467-017-01593-2