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Wireless implants used to kill bacterial infection By Jean-Pierre Joosting Wireles innovatio ns in medicine have the potential to affect significant change in the way diagnosticians and treatments work. Bacterial infections cause many problems after surgery and in hospitals as is regularly reported in the press — particularly the so-called ‘super-bug’. Currently antibiotics are typically taken orally or by injection, and rely on being transported to the site of infection via the blood. Not only do the concentrations of antibiotics vary in different parts of the body, Dissolving electronic implant, made of silk and magnesium, wirelessly heats up infected tissues. Credit: Tufts University. making some areas more difficult to treat but many bacterial infections are developing resistance to many antibiotics currently available. A novel approach using wireless implants to heat up the infected portion of the body appears to kill Staphylococcus aureus, which is known as MRSA (Methicillinresistant Staphylococcus aureus) when it becomes antibiotic-resistant. The MRSA strain is one of the so-called emerging ‘superbugs’. Wireless implants could also help deliver drugs to an infected part of the body that is difficult for antibiotics to reach or to deliver high doses without causing side-effects to other organs or parts of the body. Tolerance to many antibiotics is also of great concern, and often leads to patients not completing the full course of treatment, which in turns help develop antibiotic-resistant strains of bacteria. Recently, researchers at Tufts University, in collaboration with a team at the University of Illinois at Champaign-Urbana, have demonstrated a resorbable electronic implant that eliminated bacterial infection in mice by delivering heat to infected tissue when triggered by a remote wireless signal. The silk and magnesium devices then harmlessly dissolved in the test animals. The technique had previously been demonstrated only in vitro. “This is an important demonstration step forward for the development of on-demand medical devices that can be turned on remotely to perform a therapeutic function in a patient and then safely disappear after their use, requiring no retrieval,” said senior author Fiorenzo Omenetto, professor of biomedical engineering and Frank C. Doble professor at Tufts School of Engineering. “These wireless strategies could help manage post-surgical infection, for example, or pave the way for eventual ‘wi-fi’ drug delivery.” Implantable medical devices typically use non-degradable materials that have limited operational lifetimes and must eventually be removed or replaced. The new wireless therapy devices are robust enough to survive mechanical handling during surgery but designed to harmlessly dissolve within minutes or weeks depending on how the silk protein was processed, noted the paper’s first author, Hu Tao, Ph.D., a former Tufts post-doctoral associate who is now on the faculty of the Shanghai Institute of Microsystem and Information Technology, Chinese Academy of Sciences. Each fully dissolvable wireless heating device consisted of a serpentine resistor and a power-receiving coil made of magnesium deposited onto a silk protein layer. The magnesium heater was encapsulated in a silk “pocket” that protected the electronics and controlled its dissolution time. From warm to cool white: colour-temperature tunable LEDs By Julien happich At electronica, LED manufacturer Everlight introduced what the company claims to be the world’s first colour-temperature tunable LEDs in a simple COB (chip on board) package. After brightness dimming, tunable colour temperature is a feature that allows end users to tune the warmth of the light they receive. Typically, this feature was implemented through the use of multiple LEDs binned from cool white to warm white, behind a diffuser. With its CHI3030 27V/29W series, Everlight claims to have a very compact solution, with LEDs packaged behind concentric layers of phosphors offering different colour temperatures of white. Depending on how much of warm white or cool white you choose to light up, you can get a precise mix. A multichip solution, the CHI3030 is the largest such colourtemperature tunable COB LED, measuring 30x30mm and drawing 29W at 27V. It is available with many different tunable ranges, from 2580 to 5700K for the KH Warm White series, to a tunable range of 4745 to 7050K for the KT Cool-White series, with a typical luminous flux of 2760lm for a 2700K warm white to 2990lm for a 5700K cool white. Smaller series are also available with fewer concentric phosphor rings and operating down to 9W. According to Christopher Keusch, Director of Lighting Business for EMEA at Everlight, such colour-temperature tunable LEDs will become main stream within the next few years, adding extra tuning flexibility while making it easy for luminaire manufacturers to precisely calibrate their products at a fairly low cost. Everlight is also keen to play in the increasingly popular filament LED market, where strips of LEDs lined up in series are coated in phosphor, to be implemented into traditionallooking filament light-bulbs. The company was exhibiting several such filament LEDs ready for integration by LED bulb manufacturers. www.electronics-eetimes.com Electronic Engineering Times Europe December 2014 25


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