Glass Scaffolds for Bone Implants

Engineers at Missouri University of Science and Technology, Rolla, have developed a glass-based scaffold that could one day be used as an implant to repair injured weight-bearing bones. Previously, they had developed a glass implant strong enough for walking or lifting. But, this implant, which consists of porous scaffolding, they say, can bear weight and integrate with bone and promote bone growth. This combination of strength and bone growth opens new possibilities for bone repair.

Missouri University of Science and Technology researchers are using small, porous glass scaffolds to re generate bone.

The scaffolds are manufactured by robocasting, a computer-controlled technique to manufacture materials from ceramic slurries, layer by layer, to ensure uniform structure for the porous material. The scaffolds of the silicate glass have the same strength properties as cortical bone.

The researchers found that the bioactive glass scaffolds bonded quickly to bone and promoted significant new bone growth within six weeks. They now plan to modify the scaffolds to enhance certain attributes within bone. For example, doping the glass with copper should promote blood vessel growth within the new bone, while doping the glass with silver will give it antibacterial properties.

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Careful Monitoring Eases Prosthetic Leg Pain

UW research scientist Dave Gardner places electrodes on a patient’s residual limb. (Credit: Mary Levin, University of Washington)

When a person experiences a leg amputation, the residual limb will continue to shrink. Putting weight onto a prosthetic leg may cause discomfort in the socket, the connection point of the limb to the prosthesis. To increase amputees’ comfort and use of a prosthetic, engineers at the University of Washing ton, Seattle, are working to build better sockets. They have developed a device that tracks how much a person’s limb swells and shrinks when inside the socket. This happens when users sit, stand, or eat salty foods. In a fixed socket, fluid volume changes can be particularly painful.

The new portable device measures increase or decrease of fluid volume in a patient’s limb by receiving data from small electrodes placed in different spots on the leg. Instrument electronics can be worn in a belt pack and include a circuit board that calculates the fluid volume change in the leg, wirelessly transmitting the data to a computer.

Longer term, the researchers want to build a device that patients could wear for a couple of weeks to monitor changes in limb size as they go about their daily routines.

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Guiding Nanowire Growth for Self-Integrated Circuits

SEM image of a logic circuit based on 14 nanowires. (Credit: Weizmann Institute of Science)

Scientists working in nanoelectronics say that the components are so small that arranging them with external tools is impossible. The solution is to create the right conditions for them to self-assemble.

A team of scientists at the Weizmann Institute of Science, Rehovot, Israel, say that, for the first time, they have created self-integrating nanowires whose position, length, and direction can be fully controlled and that they have created self-integrated electronic circuits from the nanowires.

First, they prepared a surface with tiny, atom-sized grooves and then added catalyst particles to the middle of the grooves that served as nuclei for the growth of nanowires. They then created a transistor from each nanowire on the surface, producing hundreds of transistors simultaneously. The nanowires were also used to create a more complex electronic component—a functioning logic circuit called an Address Decoder.

This method makes it possible to determine the arrangement of the nanowires to suit the desired electronic circuit. The ability to efficiently produce circuits from self-integrating semiconductors could lead to a variety of technological applications, including improved LED devices and lasers.

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Creating a ‘Bioartificial’ Kidney

Design of a future implant able bioartificial kidney.

Nephrologist William Fissell IV, MD, Associate Professor of Medicine and Biomedical Engineering at Vanderbilt University, Nashville, TN, is working to create an implantable bioartificial kidney for people with chronic kidney disease.

Using silicon nanotechnology similar to computer microprocessor technology, the bioartificial kidney joins nano filters made of silicon with living human kidney cells cultured in the lab from samples harvested from deceased donors. The donated cells form a membrane positioned downstream from the device’s intake filter, out of reach of the body’s immune response, to avoid rejection. The device, he says, runs on the body’s normal blood pressure, with no other power source required.

Beyond filtering waste from the blood, the bioartificial kidney will also perform other vital functions of the kidney, including maintenance of blood pressure and pH levels and vitamin synthesis.

In clinical research conducted at the University of Michigan, intensive care patients with kidney failure were greatly helped by an externally deployed, large-scale version of the device. The challenge now is to condense the technology into a mass-producible small package.

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Ultrasound Patch Heals Venous Ulcers

Battery-operated ultrasound patch delivers therapy to heal venous ulcers. (Credit: Drexel University)

In a clinical study, researchers at Drexel University, Philadelphia, took a new approach to treat chronic wounds using an ultrasound applicator patch that delivers low-frequency, low-intensity ultrasound directly to wounds.

Venous ulcers often take months or years to heal. The scientists reported that patients receiving low-frequency, low-intensity ultrasound treatment during their weekly check-up, in addition to standard compression therapy, showed a reduction in wound size after just four weeks. In contrast, patients who didn’t receive ultrasound treatment saw their wound size increase in the same time period.

To determine the optimal frequency and treatment duration, patients were treated with 15 minutes of 20 kHz ultrasound, 45 minutes of 20 kHz ultrasound, 15 minutes of 100 kHz ultrasound, or 15 minutes of a placebo. The group receiving 15 minutes of 20 kHz ultrasound showed greatest improvement, with all experiencing complete healing by the fourth treatment.

One of the greatest challenges was designing and creating the battery-powered ultrasound patch. To make the device portable, they had to design a transducer to make it battery-powered. The resulting patch weighs 100 grams and is connected to two rechargeable lithium ion batteries.

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Medical Design Briefs Magazine

This article first appeared in the September, 2013 issue of Medical Design Briefs Magazine.

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