Scientists from the National University of Singapore have created a new type of artificial muscle, whose performance has impressed colleagues. The fact is that this new type of muscle can stretch up to five times its original length, and the weight it can lift is 80 times its own weight.
The goal of this development is to provide robots with amazing power characteristics and at the same time ensure the presence of plasticity like a person.
According to Dr Adrian Koch, who at the moment is the head of the program, the resulting material has a structure similar to the muscle tissue of living organisms.
The main interest is that, despite their strength, plasticity and flexibility, these artificial muscles respond to electrical control impulses within a fraction of a second, and this is undoubtedly a colossal result.
For example, at the moment, no mechanics or hydraulics can provide such an effect. As the head of the group says, if you equip robots with these fast-acting artificial muscles, then it will be possible to get rid of the mechanical movements of robots and get closer to the “plastic” indicators of humans or various animals. With all this, endurance, strength and accuracy of movements must exceed those of humans many times over.
This material is a complex composite, which, in turn, consists of various polymers. Using elastic polymers in this material composition with the ability to stretch 10 times and polymers that can withstand a weight 500 times greater than their own, allowed us to achieve such amazing results. As scientists report, work on the development will continue for more than one year, but over several years; it is planned to create several types of limbs for robots that will be equipped with this type of artificial muscles. It is interesting that the limb will have a weight and size half that of its human counterpart, but the person will not have much chance of winning.
Despite the fact that this development is the most interesting for a group of scientists in this particular area, in parallel they plan to use the obtained material for other purposes. For example, the new material is capable of converting mechanical energy into electrical energy and vice versa. And therefore, scientists are simultaneously developing the design of an electric generator based on soft polymer materials. Of interest here is the fact that according to plans, its weight will be about 10 kilograms, and it will be able to generate as much electricity as a traditional generator used in wind turbines and weighing 1 ton.
Artificial muscles good because they do not contain internal moving elements. This is another, rather radical, alternative to electric motors and pneumatics with hydraulics. Existing samples today are either stress- or temperature-sensitive polymers or shape-memory alloys. The former require a fairly high voltage, while the latter have a limited range of motion and are also very expensive. To create soft robots, compressed air is also used, but this requires the presence of pumps and complicates the design. To make artificial muscles, we turned to the recipe of scientists from Columbia University, who managed to combine high power, lightness, elasticity and amazing simplicity in one design. The muscles are ordinary soft silicone, into which bubbles of alcohol are injected in advance. When heated with a nichrome spiral, the alcohol inside them begins to boil, and the silicone swells greatly. However, if you put all this in a rigid braid with perpendicular weave of threads, then the swelling will turn into normal contraction - much the same way McKibben air motors work.
Since silicone does not conduct heat well, it is important not to apply too much power to the coil, otherwise the polymer will begin to smoke. This, of course, looks impressive and hardly interferes with work, but in the end it can lead to a fire. Low power is also not good, since the reduction time may then be delayed. In any case, a limiting thermal sensor and a PWM controller will not be superfluous in the design.
Methods
Silicone muscles are surprisingly simple in design, and when working with them, you really only encounter two problems: selecting power and creating fairly convenient molds for pouring.
It is convenient to make filling molds from transparent plastic sheets. Just keep in mind that the mechanism for attaching the spiral inside the polymer should be thought out in advance: after pouring it will be too late.
And materials
Soft silicone for creating muscles can be purchased at art supply stores. Braid of the required weave is usually used for organizing and wiring cables; you should look for it from electricians. The biggest difficulties arise with 96 percent ethanol, which is more difficult to buy in Russia than a tank. However, it can be replaced with isopropanol.
Popular Mechanics would like to thank the Skeleton Shop for its assistance in filming.Big muscles are the result of years of hard training and gallons of sweat. But there are people who believe that they can achieve the same look as professional athletes, but much faster and easier. This is really possible, the only question is at what cost?
Silicone muscles
The first way to get huge muscles without visiting gym- go under the surgeon's knife. Modern surgery has reached the point where it is possible to enlarge not only the breasts and lips, but also any other part of the body. And now not only women, but also men are actively inserting silicone implants into themselves to look more attractive.
There are two ways to place an implant - above the muscle and under the muscle. The first option is simpler, cheaper and less traumatic, but the problem is that such a muscle will look unnatural and be soft to the touch. In the second case, the existing muscles are literally opened up and the implant is pushed under them, after which the muscle tissue is stitched back together. Such an operation is very complex and dangerous, and recovery after it will take many months, but the result will be better - the presence of the implant will not be noticeable and the muscle will retain its inherent hardness.
Getting an implant is a huge risk, because the body may simply not accept it or respond with a serious allergic reaction. The consequences of damage to the implant can be even worse - you can even lose the part of the body where the artificial muscle was implanted.
Justin Jedlica, Silicone Ken
Perhaps the most famous example of male plastic surgery is American Justin Jedlica, aka Silicone Ken. Obsessed with the idea of being like Barbie doll's friend, he suffered about 90 plastic surgery with a total value of more than 100 thousand dollars. The guy’s face, of course, underwent the most changes, but surgeons also worked on his sculpted body, inserting silicone implants into Justin’s chest, arms, shoulders and stomach.
Push-up
Yes, yes, male push-up also exists. It is worn under a T-shirt, fastened at the back and imitates a sculpted chest and abs. A simple muscle substitute was invented in Japan, and it quickly gained popularity in Asia.
Synthol
If men rarely turn to plastic surgery, then even more dangerous chemical methods of artificially increasing muscles are used, unfortunately, much more often. The most famous drug is synthol, invented in the 1990s and quickly becoming notorious. Synthol does not have anabolic properties; it increases muscle volume by absorbing oils into muscle fibers. That is, in fact, the muscles do not become larger, they just swell.
Synthol is excreted from the body for a very long time - up to 5 years. In addition, he has a huge amount side effects, many of which are extremely dangerous and threaten athletes with serious consequences, including death. Thus, the entry of oil into the blood can cause a fat embolism, which in turn threatens a heart attack or stroke. Other possible problems include various infections, nerve damage, cysts and ulcers.
The Internet is replete with numerous examples of “victims” of synthol, and bodybuilding legends actively oppose such methods of muscle growth. “My attitude to synthol is the same as to all implants. “This is an attempt to improve the physique by cosmetic methods, avoiding the hard work that makes bodybuilding a real sport,” said six-time Mr. Olympia Dorian Yates.
The invention relates to the field of bionic prosthetics, namely to artificial muscles, which are composite materials exposed to weak electrical impulses. The artificial muscle contains nylon and/or polyethylene fiber, and it represents a medium of at least one polyorganosiloxane, at least one epoxy resin and at least one epoxy resin polymerization catalyst. The muscle is stitched with one or more threads of at least one shape memory intermetallic compound and nylon and/or polyethylene fiber. The technical result consists in providing a short response time and the possibility of rapid contraction under the influence of electrical impulses, in particular with a current density of up to 20 mA/cm 2, in eliminating the possibility of uncontrolled contraction under the influence of ambient temperature and in giving the artificial muscle self-healing properties. 10 salary files, 2 tables.
Artificial muscle
The invention relates to the field of bionic prosthetics, namely to artificial muscles, which are composite materials capable of contracting under the influence of weak electrical impulses. Artificial muscle can be used in medicine as component bionic limbs or as an independent implant, as well as in robotics in the production of high-precision manipulators.
The problem of creating materials with chemical affinity and mechanical properties close to living muscle fiber, through which movement occurs in the human or animal body, is widely known. At the moment, several types of artificial muscles have been developed, but in the way of using each of them, a number of problems arise regarding the cost of materials and limited use.
A hydraulic artificial muscle is known, including a first connector with a closed end, an elastic rubber tube, woven threads of high-strength fiber wrapped around said tube, a second connector with a closed end through which water enters the tube, two ring-shaped clamps located at the edges of the muscle, two ring-shaped clamps located in the middle part of the muscle, and two fastening elements in the shape of a cone facing inside the muscle (CN 103395072 A, A61F 2/50, 11/20/2013). The described muscle has very limited applicability: its use is only possible in robotics based on hydraulic systems.
Artificial muscle tissue is known, which is carbon nanotubes impregnated with wax and twisted in a spiral (Science magazine, volume 338, pages 928-932, November 16, 2012).
The described artificial muscle tissue is capable of lifting a weight that exceeds its own one hundred thousand times, but it has a very high cost and at the same time is characterized by increased sensitivity to environmental factors: temperature changes or microcurrents can lead to its involuntary contraction.
The closest analogue of the claimed artificial muscle is nylon or polyethylene fiber twisted in a spiral (http://nauka21vek.ru/archives/56843, 02/26/2014).
The advantages of this fiber are its ability to quickly shrink when heated, as well as its low cost, but at the same time it has a number of disadvantages. Along with its susceptibility to heat, it is not able to fully contract under the influence of weak electrical impulses, such as nerve impulses. In this regard, to create prosthetic limbs, it becomes necessary to use amplifiers and electrical-to-thermal signal converters, which, in turn, requires the use of power sources (batteries, accumulators). Increased sensitivity of the fiber to ambient temperature can lead to involuntary muscle contraction and, accordingly, movement of the artificial limb. In this regard, there is a need to use heat insulators. The above conditions complicate the design and cost of the prosthesis, and also create inconvenience in use.
The objective of the proposed invention is to create a harmless and inexpensive artificial muscle capable of receiving nerve impulses or impulses similar to them.
The technical result of the proposed invention is to provide a short response time and the possibility of rapid contraction under the influence of electrical impulses, in particular, with a current density of up to 20 mA/cm 2 , eliminating the possibility of uncontrolled contraction under the influence of ambient temperature and giving the artificial muscle self-healing properties.
The technical result is achieved due to the fact that an artificial muscle is proposed containing nylon and/or polyethylene fiber, and it represents a medium of at least one polyorganosiloxane, at least one epoxy resin and at least one epoxy resin polymerization catalyst, and the muscle is stitched with one or more threads of at least one shape memory intermetallic and nylon and/or polyethylene fiber.
The shape memory intermetallic compound can be selected from the group: Ti-Ni, Zr-Ni, Fe-Mn-Si and Heusler alloy. The shape memory effect of the listed intermetallic compounds is the most pronounced. In addition, Fe-Mn-Si is the cheapest, Ti-Ni is the most common and studied, Zr-Ni has a high response to electrical impulses.
For additional strengthening, giving the muscle smoother and more linear movements, it can be additionally stitched with elastomer threads.
To increase the amplitude of contraction of the artificial muscle under the influence of an electrical impulse, it is desirable that the nylon and/or polyethylene fiber be twisted in a spiral.
To increase the response of the muscle to a current pulse and impart precision of movement, it is desirable that one or more strands of at least one shape memory intermetallic compound are twisted in a spiral.
To further increase the speed of contraction of the artificial muscle, smoother the onset and end of its contraction under the influence of an electrical impulse, and to reduce internal friction, it is desirable that one or more strands of at least one shape memory intermetallic compound be twisted with nylon and/or polyethylene fiber in a spiral around each other.
To enhance adhesion, one or more strands of at least one shape memory intermetallic and nylon and/or polyethylene fiber may be bonded to a medium of at least one organopolysiloxane by bonding or high temperature heating followed by cooling.
As a catalyst for the polymerization of epoxy resin, you can use the Grubbs catalyst, which is the most accessible and widespread.
For additional strengthening, increasing the rate of contraction under the influence of current and improving susceptibility to weak current pulses, the artificial muscle can be additionally stitched with carbon nanotube fiber.
In the case of contact between several artificial muscles, to reduce friction between them, it is desirable that a layer of polymethylsiloxane be applied to the surface of the artificial muscle.
In order to reduce the cost of an artificial muscle while maintaining high strength and speed of response to electrical impulses, it can have the following component content, wt. %:
Polyorganosilicanes have a number of advantages compared to other living tissue simulants. Products made from them are the most harmless and durable, have a very low glass transition temperature (about -130°C), are capable of copying and preserving the specified appearance, and also in consistency they are close to biological tissues, such as natural muscles.
There are a number of materials with shape memory, for which a self-healing effect is also possible. One of the most common examples of such a material is the Ni-Ti intermetallic compound (nitinol), in which there is one nickel atom for every titanium atom. If a product made from it is deformed, then when heated it will again take its previous shape. Along with heating, due to the presence of some resistance, the product can also be returned to its shape by passing current through it. If the product is a thin thread, this can be done even with a small current, for example up to 20 mA/cm 2, which flows along the nerve fibers.
Memorizing its position under certain conditions, as well as the possibility of self-healing, is due to the disclination effect, in which grain migration occurs at the boundaries of defective zones, that is, metal defects acquire stress fields with such intense charges that the edges of the cracks come closer and the damaged intermetallic compound is regenerated.
It was found that some other nickel-based intermetallic compounds, in which the second component in its pure form has a hexagonal close-packed or body-centered cubic lattice, may have a similar property. Such intermetallic compounds include Ni-Zr and Ni-V. The use of the latter for medical purposes is excluded due to the increased toxicity of vanadium and its compounds, but its use is possible in robotics when creating manipulators.
A study of the Ni-Zr intermetallic compound, in which there is one zirconium atom for every nickel atom, showed that it is able to respond slightly faster to electrical impulses than nitinol (Ti-Ni), which is most likely due to the thermal conductivity of the second component: the thermal conductivity of zirconium at 300 K is 22.7 W/(m K), and titanium is 21.9 W/(m K).
The manifestation of shape memory under the influence of a magnetic field is known in an intermetallic compound called Heusler alloy and having the following formula: X 2 YZ, where X, Y, Z are different metals. The most common type of this alloy is Ni 2 MnGa. Shape memory is caused by a martensitic phase transition and can also be provided by electrical pulses that change the magnetic field of the Heusler alloy.
In addition to the above, an intermetallic compound with shape memory is also known - Fe-Mn-Si, which is characterized by low cost.
Other materials with shape memory are also known, for example, intermetallic compounds: Au-Cd, Cu-Zn-Al, Cu-Al-Ni, Fe-Mn-Si, Fe-Ni, Cu-Al, Cu-Mn, Co- Ni and Ni-Al. However, due to their weak shape memory and self-healing properties, they are more difficult to use in practice.
Thus, to control a bionic muscle with electrical impulses, it must be stitched with threads of at least one intermetallic compound with shape memory, and the thickness of the threads should be selected based on the magnitude of the incoming signals. Obviously, to perceive small nerve impulses, the thickness of the threads should be small - on the order of 0.02-0.5 mm. To perceive strong impulses, the thickness can be several millimeters or more.
At the same time, the use of such an intermetallic compound without a medium that plays the role of a heat insulator and electrical insulator (in this case, polyorganosiloxane) leads to the sensitivity of the intermetallic compound to the ambient temperature and thus its movement becomes uncontrolled.
There are materials that can quickly shrink under heat. They are polyethylene and nylon fibers, which are characterized by low cost, high strength and wear resistance. However, their use as artificial muscles without shape memory intermetallic filaments leads to a number of problems. Due to the low electrical conductivity of the fibers, weak current pulses are not able to activate such muscles without additional electronic devices. However, in the case of synchronous action of an impulse on both intermetallic filaments with shape memory and on nylon and/or polyethylene fiber, the muscles, through a certain number of repeated impulses, become capable of contracting with high amplitude and speed. This is due to a chain reaction: the first pulse leads to a slight contraction of the fiber, provoking a slight compression of the intermetallic compound with which it is in the same system connected by a polyorganosiloxane medium, the second pulse directly compresses the intermetallic compound, which has remembered its previous position under a current with certain characteristics (force, frequency), causing the fiber to contract with greater amplitude. With the third and subsequent impulses, the artificial muscle begins to work with high speed and amplitude of movement. Thus, an artificial muscle can work fully only when an electrical impulse is applied to both the fiber and the intermetallic threads at the same time.
Stitching the artificial muscle with elastomer threads will further strengthen it and allow smoother and smoother movements. smooth movements while maintaining other parameters. It is permissible to use various rubbers as an elastomer, preferably with high elasticity and tear resistance.
The presence of epoxy resin in the artificial muscle along with a catalyst for its polymerization, for example the most accessible Grubbs catalyst, will allow the muscle to recover in a short period of time in case of damage, for example mechanical, chemical or thermal.
When heated in its unfolded form, nylon fiber can shrink only by 4/100, polyethylene by 3/1000. However, if these fibers are twisted in a spiral, nylon acquires the ability to compress by 34/100, and polyethylene by 16/100. This effect is explained by a simple physical phenomenon: in a straightened form, the thread contracts due to an increase in its thickness; in the second case, it contracts both due to an increase in its thickness and due to a shortening of the spiral. The above values are close to the ability to reduce natural muscle fibers and can allow their counterpart to lift heavy loads.
If the threads of intermetallic compounds with shape memory are twisted in a spiral, the reaction of the artificial muscle to the same current pulse becomes better: in speed, degree of contraction and straightness of movements, that is, there are no vibrations perpendicular to the axis of passage of the spirals of the intermetallic threads. The rate and degree of contraction of intermetallic compounds is explained by a similar effect as in the case of nylon and polyethylene fibers. The absence of perpendicular vibrations is explained by the following. The movement of an intermetallic compound in the form of a straightened thread is more difficult to predict due to the fact that it is determined by the memory of the crystalline structure of the metal only at the cross section of a thin thread. If, due to some factors, the temperature in one section of the thread becomes very different from the temperature in other sections, this may lead to incorrect movement of the artificial muscle. At the same time, the movement of the intermetallic compound in the form of a thread twisted in a spiral will be determined by the memory of the crystalline structure of the metal over the entire cross-section of the spiral turn, which contributes to the stabilization and straightness of movements.
If strands of shape memory intermetallic compounds are twisted together with the fiber in a spiral around each other, this will lead to a series positive effects, namely: to a smoother beginning and end of contraction of the artificial muscle under the influence of an electrical impulse, to an additional increase in the speed of contraction and to a decrease in internal friction. Since current pulse sensitive materials react to current with at different speeds(for example, an intermetallic compound, due to its high electrical conductivity, responds to a current pulse faster), their interlacing will lead to their synchronous movement, which will reduce friction within the material and, accordingly, reduce its wear.
In addition, it is worth noting that sewing intermetallic threads and fibers in a twisted state increases their adhesion to the base and thus, during contraction, internal friction does not occur in the muscle and it works with maximum efficiency.
To further improve adhesion, which is more required if the thread is in a straightened state, it can be combined with an organopolysiloxane base, for example, by gluing or high-temperature heating and subsequent cooling. In the case of the latter, the polyorganosiloxane first softens, and with further cooling it fuses with the thread.
Gluing is best done with glue based on epoxy resin, which, in the event of rupture, quickly polymerizes under the action of a catalyst.
An artificial muscle can be additionally stitched with carbon nanotube fiber, which also contracts under the influence of electrical impulses and at the same time has high strength properties, responds to impulses at high speed and has good susceptibility to low current. Thus, its presence can somewhat improve the strength and amplitude of muscle contraction, but the cost of the latter in this case will increase.
Also, taking into account, although less, but still quite high, the cost of intermetallic compounds, especially Ni-Ti, to reduce the cost of artificial muscle with a slight loss of strength and speed of response to electrical impulses, it is better to use muscle of the following composition, wt. %:
The proposed artificial muscle can be used as an integral part of bionic limbs, or serve as an independent implant that replaces living muscle. In the latter case, the ends of the artificial muscles can be connected to the bone using medical adhesives, such as cyanoacrylate glue, osteoplast and others.
In cases where it is necessary to replace only a separate section of living muscle, its artificial analogue can also be glued to the damaged living muscle, but in such a situation there is a high probability of its non-engraftment. Factors such as contraction, tissue respiration of muscle fibers, constant metabolism and other chemical processes can cause implant rejection. In view of the above, during implantation the proposed artificial muscle is recommended to be glued to bone rather than to muscle tissue. Thus, a damaged living muscle can be completely replaced with an artificial one, but restoring a separate section of it using an artificial analogue at this stage is very problematic.
5 cylindrical samples measuring 40×7 mm were made. First, polyorganosiloxane, epoxy resin and a catalyst for its polymerization were mixed, and the mixing was carried out in two stages. At the first stage, at its melting temperature, a small amount of the polyorganosiloxane hardener, benzoyl peroxide, was added to the polyorganosiloxane, gently stirring it clockwise. Following this, after a slight thickening, epoxy resin was introduced into it. When, as the mixture cooled and the action of the hardener, the mixture became even thicker, continuing to stir it gently clockwise, at the second stage, an epoxy resin polymerization catalyst was introduced into it.
Uniform stirring in one direction of gradually thickening polyorganosiloxane and alternate introduction of epoxy resin (with a less thick consistency of the medium) and a catalyst for its polymerization (with a thicker consistency of the medium) led to the fact that these components gradually solidified in the mass of polyorganosiloxane, having a phase separation between themselves and largely without reacting. Moreover, since the resin was introduced with a less thick consistency of the medium, its distribution in the artificial muscle is more extensive, in contrast to the polymerization catalyst.
The almost solidified resulting mixture was loaded into a cylindrical form, cooled to a temperature of 65°C, stitched through it along the cylinder axis with intermetallic threads, elastomer threads, carbon nanotube fiber, nylon and polyethylene fiber, after which the resulting workpiece was cooled to room temperature, during which it was further cured and the threads were firmly fixed in the medium, and removed from the mold. The stitching was done either with a straight needle or with a needle made in a spiral. The composition and characteristics of the samples are presented in Table 1.
The samples were stitched through with 2 wires of a conductive polymer - polythiophene, in such a way that the wires had an area of contact with each thread of the intermetallic compound, nylon and/or polyethylene fiber and carbon nanotube fiber.
The upper part of the sample with the wires inserted into it was fixed in a compressive metal ring, and the wires made of a conductive polymer were connected to a power source.
A nylon thread with a suspended weight weighing 250 g was threaded through the lower part of the sample.
Next, current was applied to the sample according to the following mode: 1.5 seconds - current supply, 1 second - pause, while after the third pulse the signal delay time (response time), speed and degree of contraction of the artificial muscle were measured. The first two impulses were not taken into account, since the intermetallic compounds had not yet “remembered” the contraction movement.
After taking several measurements, the samples were blown with warm air (about 50°C) for 10 seconds and at this time the speed and degree of contraction of the artificial muscle was also measured.
These parameters were also measured with simultaneous current supply and temperature heating.
After this, the samples were damaged: a cut was made in its middle part, damaging the threads and fibers. Then the 1st and 3rd samples were left alone, and the 2nd, 4th and 5th samples were supplied with current for the third time in the same mode.
The characteristics of the supplied current, properties and reactions of the artificial muscle to current pulses, ambient temperature and damage are shown in Table 2.
According to the data obtained, the proposed bionic muscle has a short response time; it is capable of contracting under the influence of weak electrical impulses, and the degree of uncontrolled contraction under the influence of ambient temperature is so small that it can be neglected.
Also, the proposed muscle has the property of self-healing in a short period of time, and when a current signal is applied, the speed and degree of recovery increases. The speed of the muscle response to current pulses is influenced by such parameters as the frequency of the current, as well as the geometry of the arrangement of intermetallic threads and fibers; if they are twisted in a spiral and, even moreover, if they are twisted in a spiral around each other, the speed of the muscle reaction will increase .
In the presence of elastomer threads, all of the above characteristics of the muscle remain approximately the same, but its movements become smoother.
Carbon nanotube fiber has a negligible effect on response speed, strength and contraction rate. Therefore, its presence is not mandatory and it can be injected into the muscle, based on cost.
Taking into account the fact that the proposed artificial muscle is capable of achieving the stated technical result, we can judge that the myology issues regarding implantation have been resolved. At the same time, a question remains from the neurological side, namely regarding the supply of a current signal from the nerve to the muscles (including through an artificial nerve).
Since almost everything chemicals, included in the proposed artificial muscle, are inexpensive, and the most valuable component, nitinol, does not require much consumption; the claimed invention, due to its relatively low cost, can also be widely used in robotics and mechanical engineering, for example, in the production of high-precision manipulators.
1. An artificial muscle containing nylon and/or polyethylene fiber, characterized in that it is a medium of at least one polyorganosiloxane, at least one epoxy resin and at least one epoxy resin polymerization catalyst, wherein the muscle is stitched with one or more threads of at least one shape memory intermetallic compound and nylon and/or polyethylene fiber.
2. Artificial muscle according to claim 1, characterized in that the intermetallic compound with shape memory is selected from the group: Ti-Ni, Zr-Ni, Fe-Mn-Si and Heusler alloy.
3. Artificial muscle according to claim 1, characterized in that it is additionally stitched with elastomer threads.
4. Artificial muscle according to claim 1, characterized in that the nylon and/or polyethylene fiber is twisted in a spiral.
5. Artificial muscle according to claim 1, characterized in that one or more threads of at least one shape memory intermetallic compound are twisted in a spiral.
6. Artificial muscle according to claim 1, characterized in that one or more threads of at least one shape memory intermetallic compound are twisted with nylon and/or polyethylene fiber in a spiral around each other.
7. Artificial muscle according to claim 1, characterized in that one or more threads of at least one shape memory intermetallic compound and nylon and/or polyethylene fiber are connected to a medium of at least one polyorganosiloxane by gluing or high-temperature heating followed by cooling.
8. Artificial muscle according to claim 1, characterized in that Grubbs catalyst is used as a catalyst for the polymerization of epoxy resin.
9. Artificial muscle according to claim 1, characterized in that it is additionally stitched with carbon nanotube fiber.
10. Artificial muscle according to claim 1, characterized in that a layer of polymethylsiloxane is applied to its surface.
11. Artificial muscle according to claim 3, characterized in that it has the following content of components, wt. %:
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Researchers at Columbia University in New York have invented artificial muscles that can lift loads thousands of times heavier. own weight. The manufacturing technique is so simple and the materials are so accessible that anyone can start constructing soft robotics, especially if they have a 3D printer.
Despite the stunning successes, humanity is still far from real “terminators”. Algorithms are constantly being improved, machines are becoming smarter - so much so that even Elon Musk is starting to be afraid of artificial intelligence. What if Theodore Kaczynski was right? But hardware is developing at a much slower pace than software. Mechanical, pneumatic and hydraulic actuators are overly complex and often unreliable, shape memory materials are expensive and inefficient, and electroactive polymers require relatively high energy costs. What will power the androids of the future?
Doctor of Sciences Aslan Miriyev, a researcher at the Creative Machines laboratory at Columbia University, proposed his own version. The idea is to make artificial muscles from silicone elastomers saturated with ordinary drinking alcohol. Ethyl alcohol (although not necessarily ethyl alcohol) plays a key role, since muscle expansion and contraction occurs as a result of the transition of microdroplets of ethanol from the liquid phase to the gaseous phase and vice versa. This is achieved through heating and cooling: the evaporation of alcohol trapped in silicone leads to an increase in pressure and, accordingly, expansion of the elastomeric structure.
The required temperature is set by a linear or spiral electric heating element penetrating the muscle. When using ethanol maximum effect achieved by prolonged heating just above the boiling point of 78.4°C. How much higher depends on the composition of the material used, because silicone will resist expansion, and the higher the density of the material, the higher the pressure and boiling point of the alcohol. In his experiments, Aslan settled on a material with a 20 percent ethanol content as optimal. The mixture is prepared by simply mixing silicone and ethanol in the required proportions until the alcohol microbubbles are evenly distributed. The mixture can then be used for mold casting or additive manufacturing using robocasting, which is extrusion 3D printing, but without heating. For example, a syringe extruder. During experiments, artificial muscles demonstrated the ability to increase in volume by 900% and withstand repeated loads. So, a six-gram sample lifted and lowered a load weighing about six kilograms thirty times in a row, that is, a thousand times more than its own! The maximum figures are even higher: a two-gram muscle could handle a load of 12 kg, although at the limit of its capabilities.
So far so good, but muscles are supposed to contract, not expand? It's OK. The working vector can be specified by shells that restrain expansion in a given plane. For example, the biceps and triceps in the illustration above are enclosed in a fixed-length mesh, attached at the ends to the shoulder and forearm. Diametrical expansion leads to longitudinal contraction, just as it does with real muscles. This example used 13 gram muscles capable of lifting up to one kilogram of weight when heated by a 30V 1.5A nichrome wire coil. Bending can be achieved using “passive” layers of flexible materials with relatively high tensile strength applied to the “inner” side of the deformable actuator, as in the example with the gripper in the illustration below.
The laboratory cost of producing such muscles per gram did not exceed three cents. To print experimental structures from thermoplastics, desktop FDM 3D printers Ultimaker, Ultimaker 2+ and Stratasys uPrint were used, while the artificial muscles were printed directly on a homemade dual-extruder 3D printer equipped with syringe heads. The full report can be found at this link.
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