High operating force
The Sierra prosthetic hand from 1945 performed better than the newer hands. The inner hand shown in the photo are covered by a cosmetic glove.
The study, which was carried out by researchers from TU Delft and the University of Groningen, measured the force required to operate a number of contemporary body-powered prosthetic hands. The researchers compared the results to earlier measurements from 1987 and came up with remarkable results: today’s prosthetic hands perform equally or less well than those from 1987. The grip strength of the hands is insufficient and a very high operating force is required. Another remarkable result: a prosthetic hand developed in 1945 performed better in the test than the newer prosthetic hands.
TU Delft researcher Gerwin Smit: “The study offers a possible explanation why over half of all people with a body-powered prosthetic hand do not use it or even wear it. Besides this, some prosthetic arm users tend to suffer overload problems over time. These problems may well be a result of the excessive operating force required.” This is currently being researched further in Groningen and Delft.
Worldwide over 30% of prosthesis users wear a body-powered prosthesis. A body-powered prosthesis is operated by pulling a cable (a little like the brake cable on your bike). This cable is attached to a harness worn on the opposite shoulder. Subtle movements between the arm wearing the prosthesis and the opposite shoulder pull the cable taut and open the prosthesis. Another popular prosthesis is the electric prosthesis. This is worn by about 40% of prosthesis users worldwide. Then there are also cosmetic prostheses.
The big question that the researchers raised as a result of this study was why there is hardly any investment in body-powered prostheses. Gerwin Smit: “With current technology it must be possible to easily improve prostheses, resulting in enormous progress for those who have to use them. In recent decades, millions have been invested in electric prostheses. The difference in price between the types of prosthesis may have influenced this, as the retail price of an electric prosthesis is around 10 to 100 time higher than a body-powered prosthesis. This makes it more attractive from a commercial point of view to invest in electric prostheses. Yet despite the investments, electric prostheses are slower and heavier than body-powered prostheses.”
In order to solve the problems of prosthesis users, TU Delft is working on making improvements to body-powered prosthetic hands. The ultimate aim is to develop a lightweight prosthetic hand with a lower operating force and a higher grip strength.
More informationGerwin Smit:
Ilona van den Brink | EurekAlert!
MRI contrast agent locates and distinguishes aggressive from slow-growing breast cancer
25.09.2017 | Case Western Reserve University
Investigators may unlock mystery of how staph cells dodge the body's immune system
22.09.2017 | Cedars-Sinai Medical Center
At the productronica trade fair in Munich this November, the Fraunhofer Institute for Laser Technology ILT will be presenting Laser-Based Tape-Automated Bonding, LaserTAB for short. The experts from Aachen will be demonstrating how new battery cells and power electronics can be micro-welded more efficiently and precisely than ever before thanks to new optics and robot support.
Fraunhofer ILT from Aachen relies on a clever combination of robotics and a laser scanner with new optics as well as process monitoring, which it has developed...
Plants and algae use the enzyme Rubisco to fix carbon dioxide, removing it from the atmosphere and converting it into biomass. Algae have figured out a way to increase the efficiency of carbon fixation. They gather most of their Rubisco into a ball-shaped microcompartment called the pyrenoid, which they flood with a high local concentration of carbon dioxide. A team of scientists at Princeton University, the Carnegie Institution for Science, Stanford University and the Max Plank Institute of Biochemistry have unravelled the mysteries of how the pyrenoid is assembled. These insights can help to engineer crops that remove more carbon dioxide from the atmosphere while producing more food.
A warming planet
Our brains house extremely complex neuronal circuits, whose detailed structures are still largely unknown. This is especially true for the so-called cerebral cortex of mammals, where among other things vision, thoughts or spatial orientation are being computed. Here the rules by which nerve cells are connected to each other are only partly understood. A team of scientists around Moritz Helmstaedter at the Frankfiurt Max Planck Institute for Brain Research and Helene Schmidt (Humboldt University in Berlin) have now discovered a surprisingly precise nerve cell connectivity pattern in the part of the cerebral cortex that is responsible for orienting the individual animal or human in space.
The researchers report online in Nature (Schmidt et al., 2017. Axonal synapse sorting in medial entorhinal cortex, DOI: 10.1038/nature24005) that synapses in...
Whispering gallery mode (WGM) resonators are used to make tiny micro-lasers, sensors, switches, routers and other devices. These tiny structures rely on a...
Using ultrafast flashes of laser and x-ray radiation, scientists at the Max Planck Institute of Quantum Optics (Garching, Germany) took snapshots of the briefest electron motion inside a solid material to date. The electron motion lasted only 750 billionths of the billionth of a second before it fainted, setting a new record of human capability to capture ultrafast processes inside solids!
When x-rays shine onto solid materials or large molecules, an electron is pushed away from its original place near the nucleus of the atom, leaving a hole...
19.09.2017 | Event News
12.09.2017 | Event News
06.09.2017 | Event News
25.09.2017 | Trade Fair News
25.09.2017 | Physics and Astronomy
25.09.2017 | Life Sciences