Category Archives: Lucerne


Sounding out cancer cells

A device that filters cancer cells from human blood using sound could help to identify tumour cells that have spread.

Finding tumour cells in the blood indicates a cancer has metastasised – but the molecular markers that are used to identify the cells can modify them and make them unsuitable for studying how treatment is proceeding and for performing basic cancer research.

So Itziar González at the Institute for Acoustics in Madrid, Spain, and colleagues developed an alternative: a tiny vibrating plastic chamber through which a blood sample flows. The vibrations create a standing wave that deflects cells in the blood to a different degree depending on their size. Tumour cells are often larger than blood cells and so collect in a different region of the device. The process does not alter the cells.

Read the rest of this story on New Scientist’s website [html] or here [pdf] or see the brief version which appeared in print: [pdf]

Update: I should note that the version which appeared in print has an error. It says that the method makes tumor cells “unsuitable for study to confirm metastasis.” but should probably just read “unsuitable for study” since you don’t need intact cells to confirm that a cancer is metastasizing. Counting them will do for that. But to study them in the lab, as biomedical engineer David Beebe said at the meeting, researchers prefer unmodified cells.


Optical Fiber Watches Wounds

Monitoring a wound as it heals should get easier thanks to a new kind of optical fiber that could become a part of everyday bandages. The fiber’s coating alters in color in response to changes in acidity, a key health indicator in wounds. The core of the fiber carries light to and from an attached device, which caregivers could use to monitor a wound in real time, says Bastien Schyrr, a Ph.D. student in biomedical engineering at the University of Fribourg, in Switzerland, who last month presented results of a laboratory trial in which the enhanced bandage detected acidity changes in a solution containing human serum.

Wound monitoring is a “massive problem,” says bioengineer Patricia Connolly of the University of Strathclyde, in Glasgow, who was not involved in Schyrr’s work. “In the UK alone there are 200 000 people with chronic wounds.” Many of them are recovering surgery patients, diabetic patients, and others confined to bed and subject to pressure sores. To check on the healing progress, nurses must sometimes take samples from a wound—an invasive process with a risk of infection—and send them to a laboratory, where they are assessed for signs of infection and identification of bacteria. Schyrr’s fiber system, which detects the acid-induced change in the fiber by shining light into one end of a waveguide and measuring the color of the light coming out, could measure such things without having to lift the dressing.

Schyrr’s colleague Lukas Scherer, at the Swiss Federal Laboratories for Material Testing and Research, in St. Gallen, says that the main challenge for their optical-fiber biosensor was making the light-carrying fibers flexible enough so they could be included in a regular dressing. “I’m originally a synthetic chemist, and I thought you just put fiber in a machine and it makes textile,” Scherer recalls. It wasn’t that easy.

The team experimented for two years with different preparations of their proprietary fibers. The final product had to let enough light through to carry a signal from inside a bandage, like a glass fiber, yet be flexible enough to stitch into a mass-produced bandage. “When we can do tight knots with the fiber, we know it’s flexible enough,” Scherer says. But first they had to strip the outer layer of the fiber using a press—”basically like doing spaghetti,” Scherer says—before they could replace it with the acid-sensitive outer layer.

Now Schyrr is working on calibrating the light signal with acidity levels in human serum and is planning tests in live animals. The team, part of the Swiss TecInTex industrial-academic collaboration, is also in talks with several companies to commercialize the technology, Scherer says. The presence or absence of certain enzymes and other biomarkers can also indicate when skin cells begin healing, and the TecInTex collaboration plans to include enzyme monitoring in future versions of their fiber.

The fiber dressing is not the only such technology in development. Connolly is CEO of a spin-out company, Ohmedics, in Glasgow, for which her team designed a product marketed as WoundSense. Its external meter connects to a disposable sensor thatindicates the moisture level of a wound without disturbing the bandage above it. Other groups are testing biosensors, such as electronic chemical sniffers, infrared monitors, and hydrogels that transmit wound information without interfering with dressings.

By itself, the Swiss team’s wound sensor won’t be enough to tell a nonexpert caregiver what to do, because there are too many other factors involved. But it should help experts make better decisions. “It is a very big challenge to adapt wound care to the individual patient and the medical condition that you’re looking at,” says Connolly. “But the field needs these new approaches.”


Read this news story at IEEE Spectrum [html] or here [pdf]

Swiss Scientists Design a Turbine to Fit in Human Arteries

Coaches admire athletes for showing a lot of heart, and poets praise the organ’s passions, but engineers see the human cardiovascular system otherwise. The heart is a pump in a prime location, brimming with energy for the taking, says biomedical engineer Alois Pfenniger. So together with colleagues at the University of Bern and the Bern University of Applied Sciences, in Switzerland, Pfenniger has tested small turbines designed to fit inside a human artery, like an implantable hydroelectric generator.

“The heart produces around 1 or 1.5 watts of hydraulic power, and we want to take maybe one milliwatt,” Pfenniger explains. “A pacemaker only needs around 10 microwatts.” At the Microtechnologies in Medicine and Biology conference in Lucerne, Switzerland, earlier this month, Pfenniger presented results from a trial in which a tube is designed to mimic the internal thoracic artery, a millimeters-wide vessel that doctors sometimes cannibalize for surgery because it is redundant. The most efficient of the three off-the-shelf turbines he tested produced around 800 microwatts, which could run devices much more power hungry than today’s pacemakers.

Blood-pressure sensors, drug-delivery pumps, or neurostimulators could all benefit from an independent power supply. These devices are already implanted in many people, but each requires a replaceable battery or a cable to keep the power flowing. Miniaturizing such devices and eliminating cables could allow surgeons to implant them in ways that improve blood flow, reduce side effects, and add new functions. Self-contained devices could also monitor vital signs with unprecedented continuity, Pfenniger suggests.

But attendees at the meeting raised a heart-stopping possibility: Could the turbine’s turbulence provoke a blood clot? When blood gets trapped in eddies, it starts to coagulate. Pfenniger’s research showed that all three turbines produced some turbulence, though in differing amounts, and he and his colleagues acknowledge that they’ll have to address turbulence to avoid blood clots. They may try a different design or tweak an existing design, using computer simulations to improve it.

A competing design by electrophysiologist Paul Roberts of Southampton University Hospitals NHS Trust avoids that problem because it does not have a rotating part in the path of the blood flow. Instead, it’s attached to a pacemaker lead, and it works by using the blood pressure changes of a heart beating to move a magnet back and forth. But a prototype tested in a pig produced only about one-fifth of the energy a pacemaker needs—much less than Pfenniger’s turbine. Roberts has discussed commercializing his device with potential business partners; he is currently seeking government funding to improve it.

Similarly, Dan Gelvan, CEO of Sirius Implantable Systems, acquired a patent for extracting energy from the circulatory system in 2005. But Gelvan’s device, which was also tested in animals, uses a piezoelectric transducer located alongside moving organs instead of inside an artery. Gelvan says that for systems such as his, “the most important challenge is that you’re working with low-frequency, highly variable systems.”

Other research groups are experimenting with still more ways of scavenging energy from the pulse of arteries, the temperature gradients inside the body, and other neglected power sources. “The drive for all of this is to potentially reduce sizes of devices,” Roberts says, “and equally to accommodate increasing demands placed on devices, such as more diagnostics and wireless communications.”


Read this news story on IEEE Spectrum [html] or here [pdf]

Update: This story has gotten picked up by, frighteningly, a Do-It-Yourself site, bigger sites such as Gizmodo, which shows how many views the post gets, a great idea, and Discover and Popular Science.