New electronic sensor sensitivity like human skin

Researchers from Seoul National University in South Korea have been inspired by the beetle's wings to develop a flexible electronic sensor that captures the gentle footsteps of a ladybug while walking, and also distinguishes between shear and torsion, just like human skin. . It can also be tied to your wrist and used as a heart rate monitor. The Nature & Materials magazine recently published described the design of the sensor.

The researchers explained that when the beetles are resting, the two rows of hair on their wings and on the body are locked together by an electrostatic attraction called van der Waals force. They learn from the interlocking structure between beetle wings and use interweaving The "hairs" together make this electronic sensor.

"Hair" is actually a polymer fiber having a diameter of 100 nanometers and a length of 1 micron and coated with a conductive metal coating. Sandwiching the layers of polymer fibers like a sandwich, these nano "hairs" attract and lock onto each other. The soft protective layer made of polymer "wraps" it, and is connected with a wire, and can be used as a sensor. When pressing, rubbing or brushing the sensor, the position of the "hair" changes and the resistance of the sensor changes. As little as 5 Pascals of pressure can be detected by it, which is softer than the lightest touch.

By analyzing how the resistance changes in response to mechanical stress and how the resistance recovers as the force is removed, the researchers can distinguish three different types of mechanical stress: pressure from the top, shear force along the surface frictional sliding, and torsion generation Torsion. Human skin can distinguish these forces, but most artificial sensors cannot.

The new model can unify the two features of the atomic nucleus. Under the Fermi subsystem, the nucleus has both liquid and molecular-like characteristics. Recently, a French research team proposed a new model by simulating neutron stars, unifying these two aspects, and demonstrating for the first time a necessary condition for nuclear clustering into clusters. The molecular nature of the nuclear helps people understand how elements are synthesized, and this is the key to life. Related papers were published in the latest issue of Nature.

When describing the nucleus, scientists usually treat it as a quantum liquid with a diameter of about one trillionth of a billionth of a meter. On the one hand, in the study of heavy nuclear fission that contains a large number of protons and neutrons, this kind of liquid-like properties can provide a reasonable explanation; on the other hand, light nuclei are like tiny “molecules” composed of neutrons and protons. Or "atomic clusters."

Recently, a research team from the Institute of Nuclear Physics at the 11th University of Paris and the French Atomic Energy Commission (CEA) collaborated with the University of Zagreb in Croatia to propose a new model that unifies these two aspects. The researchers found a mechanism for the conversion of atomic nuclei from liquid to crystalline states. Taking J-20 as an example, the theoretical framework of the energy density function covers the cluster state and quantum liquid properties of atomic nuclei. The equations show that the clustering conditions are related to the definition of the atomic potential depth. The depth of the potential determines the energy interval of a single nuclear orbit, that is, the region of the corresponding wave function, which determines the density of nuclear clustering. This is the clustering of nuclear groups. A necessary condition.

The researchers explained that light nuclei exhibit more molecular-like behavior (tends to become crystalline), while heavy nuclei show more liquid-like behavior. When the interaction between neutrons and protons is not strong enough to fix them in the nucleus, they will be in a state of quantum liquid, leaving protons and neutrons out of place.