Pierced Tongue Used to Control Wheelchair

Powered wheelchair users, paralyzed from the neck down, can control their chair by sipping or puffing air into a straw to execute four basic commands that drive the chair. But, a new assistive technology, called the Tongue Drive System, developed at Georgia Tech, Atlanta, can allow users to drive their wheelchairs much faster than sip-andpuff wheelchairs.

Tongue Drive System headset, magnetic tongue stud and smartphone. (Credit: Maysam Ghovanloo)

The Tongue Drive System uses a magnetic stud in the person’s tongue as a joystick. Sensors in the stud relay the tongue’s position to a headset, which then executes up to six commands based on the tongue position.

On average, the performance of 11 subjects with tetraplegia using the Tongue Drive System was three times faster than their performance with the sip-and-puff system, but with the same level of accuracy, even though more than half of the patients had years of daily experience with sip-and-puff technology.

For more information, visit http://www.medicaldesignbriefs.com/component/content/article/18732. To see a video of this device in action, visit http://www.techbriefs.com/tv/tonguedrive.

Novel Implantable Battery Materials

Using natural materials in energy storage devices may increase the likelihood for use in powering devices that operate in the human body.

Where will the next source of electrode materials for batteries to power edible medical devices come from? How about marine cuttlefish? Re search ers at Carnegie Mellon University, Pittsburgh, PA, say that melanin pigments in cuttlefish ink provides the perfect chemistry and nanostructure to power tiny electronic devices that can be ingested or implanted.

The researchers say that naturally occurring melanins exhibit higher charge storage capacity compared to synthetic melanin derivatives when used as anode materials, an important component in sodium-ion batteries.

At present, high-performance energy storage systems for medical devices are designed to supply power to semi-permanent devices that are often encapsulated. These scenarios use potentially toxic electrode materials and electrolytes. Electronically active medical devices that are either biodegradable or ingestible require new energy storage materials that are benign and can operate in hydrated environments. Alternative systems using biocompatible electrode materials with aqueous sodium-ion batteries could provide energy for a variety of temporary medical devices, including biodegradable electronic implants and ingestible systems.

For more information, visit http://www.medicaldesignbriefs.com/component/content/article/18843.

Mighty Morphing Composite Material

A composite material created by scientists at Rice University changes shape in a predetermined pattern when heated and changes back when cooled. (Credit: Jeff Fitlow, Rice University)

Experiments by researchers at Rice University, Houston, TX, found that new biocompatible, stable, and inert materials they developed can morph into shapes that can be controlled by patterns written into their layers.

Two layers are needed. The first is a liquid crystal elastomer (LCE), a rubber-like material of cross-linked polymers that line up along a single axis. The other is a thin layer of polystyrene, bonded to the LCE.

The researchers discovered that the layers react to heat in a repeatable way, allowing for configurations to be designed into the material depending on the shape and aspect ratio of the LCE, the thickness and patterning of the polystyrene, and the temperature at which the polystyrene was applied.

LCEs are also reversible, which is important for biomedical applications, such as implantable materials that contract and expand in response to a stimulus.

For more information, visit http://www.medicaldesignbriefs.com/component/content/article/18836.

X-Ray Technology for Soft Tissues

A test device built at MIT as a proofof- principle for the new, higher-resolution X-ray system, using a vacuum chamber that measures 8 inches across.

Traditional X-rays generally cannot image the body’s soft tissues, except with the use of contrast-enhancing agents. But a new approach developed by researchers at MIT, Cambridge, MA, could enable the most detailed images ever, including clear views of soft tissue, without the need for contrast agents.

The team of scientists says that the key is to produce coherent beams of X-rays from an array of micronsized point sources, instead of a spread from a single, large point, as in conventional systems.

Alternating between depositing layers of material and selectively etching the material away, the researchers produced a nanostructured surface with an array of tiny tips, each of which can emit a beam of electrons. These, in turn, pass through a microstructured plate that emits a beam of X-rays, that they say, could potentially improve the resolution of X-ray imagery by a factor of 100.

For more information, visit http://www.medicaldesignbriefs.com/component/content/article/18829.

Medical Design Briefs Magazine

This article first appeared in the February, 2014 issue of Medical Design Briefs Magazine.

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