Biosensor Could Help Detect Brain Injuries During Heart Surgery

A team of engineers and cardiology experts at Johns Hopkins School of Medicine and Children’s Center have teamed up to develop a biosensor that could alert doctors when serious brain injury occurs to an infant or child during heart surgery. By doing so, the device could help doctors devise new ways to minimize brain damage or begin treatment more quickly.

In lab tests, this small biosensor detected a protein associated with brain injuries. (Credit: Weiguo Huang)

Recent studies found that after heart surgery, about 40 percent of infants will have brain abnormalities, most often caused by strokes, and can lead to problems in mental development and motor skills.

To create a biosensor that responds to the specific protein, they turned to an organic thin film transistor design, which have low cost, low power consumption, biocompatibility, and ability to detect a variety of biomolecules in real time.

On the sensor surface is a layer of antibodies that attract the protein, which changes the physics of other material layers within the sensor, altering the amount of electrical current passing through the device. These electrical changes can be monitored, enabling the user to know when the protein is present.

For more information, visit .

Robotics Technology Advances Artificial Legs

Pre-commercial version of the robotic leg de - signed by the Center for Intelligent Mechatronics

Recent advances in robotics technology enables prosthetics that can dramatically improve the mobility of lower-limb amputees, say a team of engineers at Vanderbilt University’s Center for Intelligent Mechatronics, Nashville, TN. They have been doing pioneering research in lower-limb prosthetics, and developed the first robotic prosthesis with both powered knee and ankle joints.

Some of the advances that have made bionic prostheses viable include lithium-ion batteries that store more electricity, brushless electric motors with rare-Earth magnets, miniaturized sensors built into semiconductor chips, particularly accelerometers and gyroscopes, and low-power computer chips.

These components are small and light enough that they can be combined into a package comparable to that of a biological leg and can duplicate all of its basic functions. Electric motors play the role of muscles. The batteries store enough power that the legs can operate for a full day on a single charge. Sensors serve as nerves, providing vital information on angle and force being exerted. The microprocessor provides the coordination function. And, in the most advanced systems, a neural interface enhances integration with the brain.

For more information, visit .

Developing a Mobile Seizure Alert System

The device will contain an array of noninvasive physiological sensors.

Approximately two million people, including 400,000 children, in the US are being treated for epilepsy, and, despite treatment, one-third continue to have seizures. In response, RTI International, Research Triangle Park, NC, one of the world’s leading research institutes, is working to develop a prototype mobile seizure alert system to help epilepsy patients and their caregivers cope with seizures. The alert device being developed at RTI contains an array of noninvasive physiological sensors that measure heart rate, respiration, and body orientation. It detects seizures based on physiological effects due to elevated activity of the autonomic nervous system during seizures. The researchers say that the most significant benefit of the device is the potential to decrease the incidence of sudden unexplained death in epilepsy, which is most often an unwitnessed event related to a seizure. Since the monitoring device includes cardiac and respiratory sensors, this could be life saving.

RTI will work with the Children’s National Medical Center to collect additional data and transition the proof-of-concept demonstration into a fully functional prototype device to be tested by caregivers in home settings.

For more information, visit .

Creating a Cookbook of Alloys for Bone Implants

A fractured eye socket was repaired with titanium plates and screws.

Researchers at The Ohio State University (OSU), Columbus, are building a database of new titanium alloys that, they say, will be used to reduce the stress that pins, plates, and other medical implants put on healthy bones. They are collaborating with colleagues at Penn State, University Park, PA, to build the database that will provide a reference guide to properties of alloys on the molecular scale.

Plain titanium is strong, nontoxic and easy to work with, but isn’t an ideal implant material, they explained. Bones naturally flex. However, titanium is less flexible, so wherever it connects to bone in the body, the titanium side of the connection flexes less than bone. This stresses and weakens bone over time, and can break the connection to the implant, or break the bone itself.

OSU engineers will add bits of other chemical elements to titanium to create alloys and heat them to high temperatures, so that atoms on the edges diffuse to form just a sliver of alloy with a range of compositions between the metals that more closely match bone.

For more information, visit .

Anklebot: A Robotic Walking Coach

A front view of a volunteer wearing the Anklebot in a seated posture. (Credit: Hyunglae Lee)

The ankle is a complex joint, supported by muscle, tendon, and bones, and maintaining stability and locomotion. Characterizing how it works, however, is not so straightforward says a group of researchers from MIT, Cambridge, MA.

They measured the stiffness of the ankle in various directions using a robot called the “Anklebot.” The robot is mounted to a knee brace and connected to a custom-designed shoe. As a person moves his ankle, the robot moves the foot along a programmed trajectory, in different directions within the ankle’s normal range of motion. Electrodes record the angular displacement and torque at the joint, which researchers use to calculate the ankle’s stiffness.

The Anklebot is designed to train and strengthen lower-extremity muscles by sensing a person’s ankle strength and adjusting its force accordingly. In physical therapy sessions, stroke patients were outfitted with the robot and it moved their ankle back and forth and side to side. The robot senses when patients begin moving their ankles on their own, and offers less assistance.

For more information, visit .

Metamaterial May Improve Depression

Shown is the headpiece, a square array of 64 circular metallic coils, next to computer simulations of a brain stimulation. (Credit: Joseph Xu)

A new headpiece for brain stimulation technique, designed by engineers at the University of Michigan, Ann Arbor, may considerably improve treatment of tough cases of depression. Computer simulations have shown that the device—a square array of 64 circular metallic coils—could hit more precise targets in the brain that are twice as deep as they can currently reach.

In transcranial magnetic stimulation, specialized coils create a fluctuating magnetic field that generates a weak electrical field that noninvasively travels through the scalp and skull to activate neurons in targeted parts of the brain. But, it can send signals only 2 centimeters into the brain before it causes uncomfortable muscle contractions. In simulations, at 2.4 centimeters, the new system excited 2.6 times less unwanted brain volume than today’s systems.

Working with metamaterials, which can focus light to a point smaller than its wavelength, they settled on a headpiece design with a surface of loops. The prototype needs only one power source, as opposed to 64. Having just one would make it easier to use on patients and more affordable.

For more information, visit .