Researchers at MIT have found a way to produce contracting fibers that could be used as artificial muscles for robots, prosthetic limbs, or other mechanical and biomedical applications.

The fibers were developed by MIT postdoc Mehmet Kanik and MIT graduate student Sirma Örgüç, working with professors Polina Anikeeva, Yoel Fink, Anantha Chandrakasan, and C. Cem Tasan, and five others, using a fiber-drawing technique to combine two dissimilar polymers into a single strand of fiber.

The key to the process is mating together two materials that have very different thermal expansion coefficients – meaning they have different rates of expansion when they are heated. This is the same principle used in many thermostats, for example, using a bimetallic strip as a way of measuring temperature. As the joined material heats up, the side that wants to expand faster is held back by the other material. As a result, the bonded material curls up, bending toward the side that is expanding more slowly.

Using two different polymers bonded together, a very stretchable cyclic copolymer elastomer and a much stiffer thermoplastic polyethylene, Kanik, Örgüç and colleagues produced a fiber that, when stretched out to several times its original length, naturally forms itself into a tight coil. But what happened next actually came as a surprise when the researchers first experienced it. “There was a lot of serendipity in this,” Anikeeva recalls.

As soon as Kanik picked up the coiled fiber for the first time, the warmth of his hand alone caused the fiber to curl up more tightly. Following up on that observation, he found that even a small increase in temperature could make the coil tighten up, producing a surprisingly strong pulling force. Then, as soon as the temperature went back down, the fiber returned to its original length. In later testing, the team showed that this process of contracting and expanding could be repeated 10,000 times “and it was still going strong,” Anikeeva says.

The fibers can span a wide range of sizes, from a few micrometers (millionths of a meter) to a few millimeters (thousandths of a meter) in width, and can easily be manufactured in batches up to hundreds of meters long. Tests have shown that a single fiber is capable of lifting loads of up to 650x its own weight.

The fibers are made using a fiber-drawing system, which makes it possible to incorporate other components into the fiber itself. Fiber drawing is done by creating an oversized version of the material, called a preform, which is then heated to a specific temperature at which the material becomes viscous. It can then be pulled, much like pulling taffy, to create a fiber that retains its internal structure but is a small fraction of the width of the preform.

Such fibers could find uses as actuators in robotic arms, legs, or grippers, and in prosthetic limbs, where their slight weight and fast response times could provide a significant advantage.

Some prosthetic limbs today can weigh as much as 30 lb, with much of the weight coming from actuators, which are often pneumatic or hydraulic; lighter-weight actuators could thus make life much easier for those who use prosthetics. Such fibers might also find uses in tiny biomedical devices, such as a medical robot that works by going into an artery and then being activated.

Read the full article by David L. Chandler here.

Technology recently developed by a group of researchers at the Chinese University of Hong Kong, makes the possibility of powering your devices by walking not be far out of reach.

An energy harvester is attached to the wearer's knee and can generate 1.6 microwatts of power while the wearer walks without any increase in effort. The energy is enough to power small electronics like health monitoring equipment and GPS devices.

"Self-powered GPS devices will attract the attention of climbers and mountaineers," notes author Wei-Hsin Liao, professor in the department of mechanical and automation engineering.

The researchers used a special smart macrofiber material, which generates energy from any sort of bending it experiences, to create a slider-crank mechanism -- similar to what drives a motor. The authors chose to attach the device to the knee due to the knee joint's large range of motion, compared to most other human joints.

"These harvesters can harvest energy directly from large deformations," Liao says.

Due to the continuous back-and-forth the material will encounter when the wearer walks, every time the knee flexes, the device bends and generates electricity. This means the harvester can "capture biomechanical energy through the natural motion of the human knee," according to Liao.

Previous wearable energy harvesters took advantage of the vibration caused in the device as a result of motion, which comes with drawbacks regarding efficiency.

"The frequency of human walking is quite slow, which significantly decreases the energy-harvesting capability," Liao says. Because the group's device uses a different method, it bypasses this limitation.

The prototype weighs only 307g (0.68 lb) and was tested on human subjects walking at speeds from 2km/h to 6.5km/h (about 1mph to 4mph). The researchers compared the wearers' breathing patterns with and without the device and determined that the energy required to walk was unchanged, meaning that the device is generating power at no cost to the human.

The researchers note the advantages of an efficient, wearable energy harvester and look towards future commercialization of the technology.

"Self-powered equipment can enable users to get rid of the inconvenient daily charge," Liao says. "This energy harvester would promote the development of self-powered wearable devices."

The group describes the technology in Applied Physics Letters, from AIP Publishing.

The article, "Macro fiber composite-based energy harvester for human knee," is authored by Fei Gao, Gaoyu Liu, Brendon Lik Hang Chung, Hugo H. Chan and Wei-Hsin Liao. 

In response to the March 2019 closure of a large device sterilization facility, the FDA is taking steps to ensure that hospitals, health care providers, and patients have access to medical devices that are safely and effectively sterilized.

The FDA is also sponsoring two public innovation challenges to encourage new developments in medical device sterilization.

• Challenge 1: Identify New Sterilization Methods and Technologies
• Challenge 2: Reduce Ethylene Oxide Emissions

Sterilization is critical in the medical industry. Suzanne B. Schwartz, M.D., M.B.A., Deputy Director of the Office of Strategic Partnerships and Technology Innovation and Acting Office Director, Center for Devices and Radiological Health (CDRH), and CAPT Elizabeth F. Claverie-Williams, M.S., Microbiologist and Branch Chief, Infection Control Devices Branch, CDRH cover the topic of sterilization on the FDA's website in more detail.

ABB will introduce collaborative robots to medical laboratories as it opens a new healthcare hub at the Texas Medical Center (TMC) innovation campus in Houston, Texas. The facility will be ABB’s first dedicated healthcare research center when it opens in October 2019. ABB’s research team will work on the TMC campus with medical staff, scientists and engineers to develop non-surgical medical robotics systems, including logistics and next-generation automated laboratory technologies.

Sami Atiya, president of ABB’s Robotics and Discrete Automation business says, “The next-generation laboratory processes developed in Houston will speed manual medical laboratory processes, reducing and eliminating bottlenecks in laboratory work and enhancing safety and consistency. This is especially applicable for new high-tech treatments, such as the cancer therapies pioneered at the Texas Medical Center, which today require manual and time-consuming test processes.”

Today, a limiting factor to the number of patients who can be treated is the need for highly skilled medical experts who spend a large part of their day doing repetitive and low value tasks, such as preparing slides and loading centrifuges. Using robots to automate these tasks will enable medical professionals to focus on more highly skilled and productive work, while ultimately helping more people to receive treatment through dramatically speeding the testing process.

ABB has analyzed a wide range of current manual medical laboratory processes and estimates that 50% more tests could be carried out every year using automation, while training robots to undertake repetitive processes will reduce the need for people to do tasks which cause repetitive strain injury (RSI).

As the world population ages, countries are spending an increasingly larger proportion of their GDP on healthcare. In addition to improving the quality of patient care, increasing healthcare efficiency through automation can ease some of the societal, political and financial challenges that this will cause. The market for non-surgical medical robots is estimated to reach nearly 60,000 by 2025 with the market almost quadrupling vs. 2018, according to an internal ABB research.

ABB’s collaborative robots are well suited to medical facilities as they don’t require safety fences to operate safely and efficiently alongside people. The robots will undertake a range of repetitive, delicate and time-consuming activities including dosing, mixing and pipetting tasks as well as sterile instrument kitting and centrifuge loading and unloading.

Houston is a focal point for medical technology research globally and the TMC innovation ecosystem is the ideal location for ABB’s new healthcare hub. A 20-strong team from ABB Robotics will work in the new 5,300ft² (500m²) research facility, which includes an automation laboratory and robot training facilities, as well as meeting spaces for co-developing solutions with innovation partners.