Scientists at the American Institute of Physics (AIP) have developed a biomechanical energy collector that generates electricity from walking movements . In the future, the energy collector could be used in everyday life to charge batteries from smartphones and other small devices.
To do this, a thin strip of composite material will be attached to the side of the knee. Squeezing and pulling the strip apart while running generates up to 1.6 milliwatts of electricity without the user having to use more force.
An energy collector made of a flexible carbon strip generates electricity from the movements of the knee while walking. In the future, the technology could charge the batteries of small devices on the go.
The large range of movement of the knee enables electricity generation:
According to the research published in Applied Physics Letters , the generator is based on a carbon fiber composite. The scientists around Fei Gao use the knee to generate electricity , “because it has a larger range of motion than other joints such as the ankle or hip” and can thus generate a larger amount of energy.
As-Hsin Liao explains, “the material generates energy from deformations.” This is done by alternately compressing and relaxing the strip while walking, releasing energy and releasing energy inside the material that can be passed on as electricity to external devices.
Tasks of biomechanics:
Since biomechanics is explained by physical laws, it is one of the unpopular topics in sports science. It is unthinkable to forego biomechanics in applied sports science. The biomechanics are much larger than initially thought. Of course, the focus is on optimizing the performance of sporting disciplines through performance biomechanics. This can be illustrated clearly using the example of shot put.
To describe the stroke distance, the stroke distance, ball flight distance, departure angle, departure height, vertical departure speed, horizontal departure speed and spatial departure speed are necessary. The examination of these individual factors enables the optimization of the technique in shot put. The biomechanical principles in movement science serve to record mechanical determinants in sport.
However, not only is performance enhancement a part of biomechanics, but also preventive sports are finding their way into biomechanics. For example, studies on the lifting technique of objects to relieve the spine and prevent back pain are examples of the use of preventive biomechanics. Furthermore, studies on body structure features are the subject of anthropometric biomechanics. In the foreground is the constitution of the athlete.
Prototype successfully tested on the treadmill:
Three test subjects who tried the 300 gram prototype on the treadmill report that the energy collector does not hinder running and does not cause any noticeable additional strain on the muscles. Depending on the speed, between 1.1 and 1.6 milliwatts of electricity were generated. The voltage was up to 105 volts during the experiment.
According to the researchers, there were “no statistically significant differences in the metabolic costs of the test subjects” when using the energy converter or running on the treadmill for comparison without an energy converter. The scientists also explain that the energy collector is easy to put down and can be used several times.
Liao predicts that “self-sufficient devices will make cumbersome daily charging superfluous” in the future, since integrated biomechanical energy collectors continuously generate electricity while running.
The biomechanics are basically differentiated into an external and an internal biomechanics.
The outer biomechanics examined changes in location of bodies by means of mechanics and is divided into the kinematics and dynamics. The kinematics deals with the changes in location in terms of space and time. The dynamics that deal with emerging forces consist of statics and kinetics (see figure)
The internal biomechanics are divided into active and passive internal forces and active and passive external forces.
- Movement is always a change of location of a body in space and time.
- A form of force is always required to set a body in motion.
- Different manifestations of strength
Active internal forces : are muscle forces that set the body or part of the body in motion
Passive internal forces: this means the elastic properties of the muscles and connective tissue
Active external forces: Active external forces are forces that set the human body or sports equipment in motion. Examples are wind when sailing, current when swimming etc.
Passive external forces: The passive external forces enable movement at all. The sluggishness of the water enables swimming. The passive external forces can also be a hindrance. (e.g. sprint on ice)
Basic principles of classic mechanics
Law of inertia:
A body remains in its state of uniform movement as long as no force acts on it. Example: A vehicle is stationary on the road. In order to change this state, a force has to act on the vehicle. If the vehicle is in motion, external active forces act on it (wind resistance and friction). Forces that can accelerate a vehicle are motor and downhill force.
The change in motion is proportional to the applied force and occurs in the direction in which that force acts.
This law states that a force is required to accelerate a body.
An opposing force of the same size always arises for an active force. In the literature one often finds the name actio = reactio. This third law of classical mechanics means that the force that is applied around your own body or an object in motion creates a counterforce.
Force F = m * a:
Force means mass x acceleration. An acting force on a body causes a change of location. Therefore, heavier cars also need more powerful engines to accelerate at the same speed.
Momentum p = m * v:
The impulse is the result of mass and speed.
This is clearly at a premium in tennis . If the mass (weight of the racket) is high, the hammering speed does not have to be as high as that of a light racket in order to achieve the same effect.
Body center of gravity (KSP):
The center of gravity is the fictional point that lies in, on or outside the body. In the KSP, all acting forces have the same effect. It is the point of gravity.
With rigid bodies, the KSP is always in the same place. However, this is not the case with human bodies due to the deformation.
Is the property of a body to resist an attacking force. (A heavy car rolls downhill faster than a light one with the same volume).