A contact type plasma therapeutic apparatus

Abstract

The present invention provides a contact plasma therapeutic apparatus, comprising: an electrode and magnet module, connected to a housing through a flexible connection, the electrode and magnet module including an upper electrode and magnet part and a lower magnet part near the skin end; the upper electrode and magnet part successively includes a first permanent magnet, a first electrolytic iron, and an insulating dielectric layer; the lower magnet part near the skin end includes a second electrolytic iron and a second permanent magnet, fixed by an insulating cap of the outer housing; the first electrolytic iron and the hollow spherical electrode are electrically connected by a thread; the insulating dielectric layer has uniform micropores along the Z direction; the insulating dielectric layer is divided into upper and lower layers, and the two layers of dielectric are installed with a gap to form a micro-air gap; the first permanent magnet is magnetized in the vertical direction to generate a steady magnetic field in the Z-axis direction, which is used to confine electrons and form a micro-discharge channel to enhance the magnetic field effect; air is pumped by a micro air pump so that the air pressure in the micro-air gap of the insulating dielectric is lower than the atmospheric pressure, and the discharge electric field intensity is enhanced by stepwise breakdown.

Description

Technical Field

[0001] The present invention belongs to the technical field of gas discharge, and particularly relates to a contact type plasma therapeutic apparatus. Background Art

[0002] Atmospheric pressure non-thermal plasma is a partially ionized gas rich in electrons, positive and negative ions, excited atoms and free radicals. When it acts on bacteria, cells and tissues, it exhibits biological effects, such as effectively killing various pathogenic microorganisms such as bacteria, fungi and viruses, while promoting wound healing, tissue regeneration and inducing apoptosis of cancer cells. Therefore, a research boom on atmospheric pressure non-thermal plasma medicine has been set off worldwide.

[0003] During the process of plasma contacting the human body, the discharge intensity, stability and uniformity of the discharge are very important. Excessive discharge, unstable and local discharge may form filamentary discharge, causing the current value flowing through the human body to exceed the safety value, resulting in damage to human tissues or discomfort such as pricking or electric shock. In addition, the electrode form, the thickness of the insulating dielectric layer between the electrodes, and the electrode spacing have a great influence on the discharge intensity, stability and uniformity of the discharge. Increasing the thickness of the insulating dielectric layer helps to limit the discharge current and discharge intensity, but requires a higher breakdown voltage. At the same time, the discharge power is reduced, and there are also potential safety hazards.

[0004] Patent CN 201310620623.4 discloses an integrated floating electrode plasma beauty apparatus, and the efficiency and temperature of plasma generation can be adjusted by adjusting the power of the high-voltage pulse.

[0005] Patent CN 106993369A discloses a portable low-temperature plasma generating device with a human body protection function, which realizes the protection function of human body safety in abnormal states and protects human body safety through real-time detection of the discharge current and feedback control. However, these two patent technologies do not solve the problem of plasma generation uniformity.

[0006] Based on the above technical background analysis, during the process of plasma acting on the human body, the stability and uniformity of the discharge are the main problems. Summary of the Invention

[0007] Aiming at the problems existing in the background art, the present invention aims to provide a contact type plasma therapeutic apparatus, which generates uniform and stable low-temperature plasma to avoid skin damage and discomfort, remove skin / tissue bacterial biofilms, contribute to the generation of collagen and elastin, and promote wound coagulation, healing, tissue regeneration, skin whitening, freckle removal, etc.

[0008] The technical solution of the present invention is: a contact type plasma therapeutic apparatus

[0009] It includes: an electrode and magnet module, which is connected to a housing through a flexible connection. A battery management module and a high-voltage excitation module are arranged inside the housing.

[0010] The electrode and magnet module includes an upper electrode and magnet part and a lower magnet part near the skin end.

[0011] The upper electrode and magnet part successively includes a first permanent magnet, a first pure iron for electrical engineering, and an insulating dielectric layer from bottom to top. The lower magnet part near the skin end includes a second pure iron for electrical engineering and a second permanent magnet, which is fixed by an insulating cap of the outer housing.

[0012] The first pure iron for electrical engineering is electrically connected to the hollow spherical electrode through a thread. The insulating dielectric layer has uniform micropores along the Z direction.

[0013] The insulating dielectric layer is divided into upper and lower layers, and the two layers of dielectrics are installed with a gap to form a micro-air gap. The first permanent magnet is magnetized in the vertical direction to generate a steady magnetic field in the Z-axis direction, which is used to confine electrons and form a micro-discharge channel to enhance the magnetic field effect.

[0014] The first pure iron for electrical engineering has a central first pure iron for electrical engineering channel that penetrates radially. The central channel is connected to the axial channel of the hollow spherical electrode. The hollow spherical electrode has a connection interface on the side, which is connected to the axial channel. A micro-air pump is connected to the hollow spherical electrode interface through a hose. By pumping air with the micro-air pump, the micro-air gap between the two layers of dielectrics passes through the inner air gap of the insulating side wall, the central channel of the first pure iron for electrical engineering, the axial channel of the hollow spherical electrode, and the hose to form an air extraction channel, so that the air pressure in the micro-air gap of the insulating dielectric is lower than the atmospheric pressure, and the discharge electric field strength is enhanced by step-by-step breakdown.

[0015] The battery management module includes functions such as a rechargeable battery, a power management controller, and battery power display. When the battery power is different, the corresponding power is indicated by an LED. When the power is insufficient, the lowest power is indicated by a red LED. When the battery is fully charged, the full power is indicated by a green LED. When the working time is up, the power supply to the high-voltage excitation module is stopped.

[0016] The high-voltage excitation module includes a control signal, a modulation signal, and a high-voltage output part. Under the action of the main control signal, the high-voltage power module is boosted and shaped to output a rated pulsed high voltage with a certain voltage and frequency. At the same time, the number of pulses and the pulse width output by the high-voltage output part per unit cycle are controlled by the modulation signal. Under the coordinated action of the main control signal and the modulation signal, the high-voltage power module can output a rated pulsed high voltage, and parameters such as the voltage amplitude, frequency, number of pulses, and pulse width can be controlled by the modulation signal.

[0017] The high-voltage power supply module outputs a high-voltage electrode, one end of which is spherical and fixed on an insulating bracket. The spherical high-voltage electrode is connected to the lower hollow spherical electrode through a tight fit. The other end of the lower hollow spherical electrode has a thread and can be electrically connected to the electrolytic iron. The electrode, the magnet module, and the housing are integrated through a flexible connection. The electrode and the magnet module can rotate and adjust their positions around the hollow spherical electrode, so as to easily adapt to different shapes of the human body surface.

[0018] Beneficial effects:

[0019] Through the electrode configuration of the upper electrode, the magnet, and the lower magnet near the skin end, the main advantages of the device are:

[0020] 1. The permanent magnet generates a steady magnetic field in the Z-axis direction and is parallel to the electric field direction, so that the steady magnetic field applied to the discharge space is a parallel magnetic field. Under the excitation of the high-voltage power supply module and the action of the parallel permanent magnetic field, when the skin tissue approaches or contacts the insulating dielectric layer, the parallel magnetic field can confine the electrons in the discharge channel and weaken the dissipation process of the electrons in the discharge channel, enabling the formation of a discharge channel that could not be formed originally, thereby increasing the number of micro-discharge channels. The micro-discharge channels overlap with each other in space, achieving discharge uniformity and avoiding the generation of filamentary discharge.

[0021] 2. Under the action of the parallel magnetic field, the density of positive ions near the cathode increases, making the "enhanced electric field" intensity near the cathode greater. Its effect is equivalent to the uniform breakdown starting from a smaller gap. The ionization of secondary electrons near the cathode is enhanced, the density of seed electrons in the breakdown stage increases, and the discharge intensity increases, maintaining discharge uniformity and improving the plasma chemical activity.

[0022] 3. Due to the magnetic field action in the Z-axis direction, the electric field enhancement effect and the micro-discharge increase effect further reduce the pressure in the micro-air gap. Under the excitation of the pulsed high voltage, it is easier to form a stable plasma in the micro-air gap first, which is equivalent to further reducing the discharge distance and enhancing the discharge electric field, thereby forming a secondary breakdown between the insulating dielectric and the tissue to form a stable plasma and further enhancing the discharge intensity. And due to the micro-discharge increase effect of the magnetic field, the enhanced plasma will not form filamentary discharge to damage human tissues.

[0023] Therefore, the present invention generates an electric field enhancement effect and a microdischarge increase effect through the magnetic field in the Z-axis direction; furthermore, a step-by-step breakdown effect is generated (firstly, the micro-air gaps in the insulating medium are broken down), which further reduces the discharge distance and enhances the discharge electric field; at the same time, since the magnetic field can confine the electrons in the discharge channel and increase the microdischarge effect, the enhanced plasma can still maintain stable and uniform discharge, avoiding the generation of filamentary discharge and causing harm to human tissues. At the same time, the micropores uniformly distributed in the insulating dielectric layer also contribute to dissociating the discharge channel, generating uniform and stable low-temperature plasma, and avoiding the generation of filamentary discharge. It can avoid skin damage and discomfort, remove the bacterial biofilm on the skin / tissue, contribute to the generation of collagen and elastin, and promote wound coagulation, healing, tissue regeneration, skin whitening, freckle removal, etc. Description of the Drawings

[0024] Figure 1 It is an axonometric view of the plasma therapeutic apparatus;

[0025] Figure 2 It is a top view of the plasma therapeutic apparatus;

[0026] Figure 3 It is a cross-sectional view of the plasma therapeutic apparatus;

[0027] Figure 4 It is a detail view of the electrode and magnet module;

[0028] Figure 5 It is a drawing of the air extraction direction of the electrode part.

[0029] In the figure: 1 - Electrode and magnet module; 2 - Flexible connection; 3 - Housing; 4 - Battery level indicator; 5 - Switch; 6 - Display screen; 7 - Power adjustment knob; 8 - Charging socket; 9 - Pressing block; 10 - First permanent magnet; 11 - Fixed block; 12 - First pure electrical iron; 13 - Insulating medium; 14 - Second pure electrical iron; 15 - Second permanent magnet; 16 - Insulating cap; 17 - Hollow spherical electrode; 18 - Sector-shaped constriction; 19 - High-voltage electrode; 20 - First insulating bracket; 21 - Second insulating bracket; 22 - High-voltage power supply module; 23 - Rechargeable battery; 24 - Battery management controller; 25 - Micro air pump; 26 - Connection interface; 27 - Micro air gap; 28 - Central channel; 29 - Axial channel; 30 - Insulating protrusion; 31 - Air gap inside the insulating side wall. Detailed Embodiment

[0030] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0031] As Figure 1-2 shown, the atmospheric pressure low-temperature plasma treatment apparatus of the present invention includes an electrode and a magnet module 1, which is connected to a housing 3 through a flexible connection 2. A power display lamp is provided on the housing 3; a switch 5 is provided at the bottom of the housing; a display screen 6; a power adjustment knob 7; a charging socket 8; a battery management module and a high-voltage excitation module are provided inside the housing 3. The low temperature refers to normal temperature, for example, in the range of 20-35 degrees.

[0032] As Figure 3 shown, the electrode and magnet module 1 is the main part for generating uniform and stable low-temperature plasma in the present invention. Its main body includes an upper electrode and magnet part directly connected to the output of a high-voltage power module 22 and a lower magnet part near the skin end.

[0033] The upper electrode and magnet part, as Figure 3-4 , from bottom to top, are a first permanent magnet 10, a first pure electrical iron 12, an insulating medium 13, etc. The first permanent magnet 10 uses a permanent magnet with a high magnetic induction intensity. The first permanent magnet 10 is magnetized in the vertical (Z coordinate axis, along the central axis of the treatment apparatus) direction, and thus can generate a steady magnetic field in the Z-axis direction. A circular hole is reserved at the center position of the first permanent magnet 10 to allow the other end of the hollow spherical electrode 17 to pass through the center of the first permanent magnet 10. The first pure electrical iron 12 has a high magnetic permeability (the relative magnetic permeability can reach 10 5 ), and is in direct and close contact with the first permanent magnet 10. Moreover, the diameter of the first pure electrical iron 12 is larger than the size of the first permanent magnet 10. Therefore, the first pure electrical iron 12 can collect all the magnetic induction lines generated by the first permanent magnet, with less magnetic leakage, making the magnetic induction intensity in the discharge space large enough to easily form uniform and stable plasma. The first permanent magnet 10 is fixed by installing fixing blocks 11 on both sides.

[0034] The first pure electrical iron 12 also serves as a discharge electrode. The center of the first pure electrical iron 12 has a thread and is electrically connected to the hollow spherical electrode 17 through the thread. The insulating dielectric layer 13 has uniform micropores along the Z direction. The uniformly distributed micropores help dissociate the discharge channel, generate uniform and stable plasma, and avoid the generation of filamentous discharge. The insulating dielectric layer 13 is in close contact with the first pure electrical iron 12. To avoid the air gap between the dielectric layer 13 and the first pure electrical iron 12, an insulating glue is adhered to the lower end of the insulating dielectric layer 13. The first permanent magnet 10, the first pure electrical iron 12, the insulating dielectric layer 13, etc. in the upper electrode and magnet part are fixed by a sector-shaped necking 18 and a lower pressing block 9.

[0035] The permanent magnet generates a steady magnetic field in the Z-axis direction and is parallel to the electric field direction, so that the steady magnetic field applied to the discharge space is a parallel magnetic field. Under the excitation of the high-voltage power supply module, under the action of the parallel magnetic field, when the skin tissue approaches or contacts the insulating dielectric layer, the parallel magnetic field can confine the electrons in the discharge channel, weaken the dissipation process of the electrons in the discharge channel, enable the formation of a discharge channel that could not be formed originally, thereby increasing the number of micro-discharge channels. The micro-discharge channels are parallel to each other in space, achieving discharge uniformity and avoiding the generation of filamentary discharge. Further, under the action of the parallel magnetic field, the density of positive ions near the cathode increases, making the intensity of the "enhanced electric field" near the cathode greater. Its effect is equivalent to the uniform breakdown of the discharge starting from a smaller gap. The ionization of secondary electrons near the cathode is enhanced, the density of seed electrons in the breakdown stage increases, the discharge intensity increases, while maintaining the discharge uniformity, the plasma chemical activity is improved.

[0036] The lower magnet part near the skin end includes a second armco iron 14 and a second permanent magnet 15. The second armco iron 14 and the second permanent magnet 15 can be in a ring shape, and the lower magnet part is fixed by the insulating cap 16 of the outer housing. The thicknesses of the second armco iron 14, the second permanent magnet 15, and the insulating cap 16 are less than 5 mm.

[0037] The upper electrode and the second permanent magnet 15, the second armco iron 14, and the insulating dielectric layer 13 in the magnet form an independent sealed space through the pressing block 9, the fixing block 11, and the insulating protrusion 30. The insulating protrusion 30 and its side surface are designed as a threaded structure and are threadedly connected to the open end of the sector-shaped reduced opening 18. The insulating dielectric layer 13 is divided into upper and lower layers, and the two layers of dielectrics are installed with a gap to form a micro-air gap 27. The first armco iron 12 has a central channel 28 of the central first armco iron that penetrates along the radial direction, as Figure 5As shown, the central channel 28 is connected to the axial channel 29 of the hollow spherical electrode. The hollow spherical electrode has a connection interface 26 on the side, which is connected to the axial channel 29. The micro air pump 25 is connected to the connection interface 26 of the hollow spherical electrode through a hose. When the switch is turned on, the micro air pump 25 is in the working state and pumps air. The micro air gap between the two layers of dielectrics passes through the air gap 31 in the insulating side wall, the central channel 28 of the first electrolytic iron, the axial channel 29 of the hollow spherical electrode, and the hose to form an air extraction channel, so that the air pressure in the micro air gap 27 of the insulating dielectric is lower than the atmospheric pressure. Under the excitation of the pulsed high voltage, plasma is first generated in the micro air gap, which is equivalent to further reducing the discharge distance between the electrodes and enhancing the discharge electric field. Thus, it is easy to form a secondary breakdown between the insulating dielectric and the human tissue to generate stable plasma and process the human tissue. It can be seen that due to the magnetic field effect in the Z-axis direction, the electric field enhancement effect and the micro-discharge increase effect are achieved, and the pressure in the micro air gap is further reduced. Under the excitation of the pulsed high voltage, it is easier to form stable plasma in the micro air gap first, which is equivalent to further reducing the discharge distance and enhancing the discharge electric field. Thus, a secondary breakdown is formed between the insulating dielectric and the tissue to generate stable plasma, further enhancing the discharge intensity. And due to the micro-discharge increase effect of the magnetic field, the enhanced plasma will not form filamentous discharge to harm the human tissue.

[0038] The battery management module includes a rechargeable battery 23, a power management controller 24, and a power indicator 4. When the battery power is different, the corresponding power is indicated by the LED. When the power is insufficient, the lowest power LED lights up in red. When the battery is fully charged, the full power green LED lights up. When the working time is up, the power supply to the high-voltage excitation module is stopped. The high-voltage power supply module 22 is used to output high-voltage pulses to the high-voltage electrode 19 under the action of the main control signal and the modulation signal. Under the action of the main control signal, the high-voltage power supply module outputs a rated pulsed high voltage with a certain voltage and frequency after boosting and shaping. At the same time, the number of pulses output per unit cycle and the pulse width of the output high-voltage pulses are controlled by the modulation signal. Under the action of the main control signal and the modulation signal, the high-voltage power supply module can output pulsed high voltages of 2 kV - 9 kV, and the modulation signal frequency can be adjusted between 10 Hz - 5 kHz.

[0039] The high-voltage power supply module outputs high-voltage pulses to the high-voltage electrode 19. One end of the high-voltage electrode 19 has a spherical electrode, which is fixed on the first and second insulating brackets 20 and 21. The spherical electrode is closely and cooperatively connected to a lower-end hollow spherical electrode 17. The other end of the lower-end hollow spherical electrode 17 has a thread and can be electrically connected to the first electrolytic iron 12. The electrode and the housing of the magnet module 1 have a fan-shaped necking 18. The fan-shaped necking 18 and the housing 3 are integrated through a flexible connection 2. The electrode and the magnet module 1 can rotate and adjust the position with the hollow spherical electrode 17 as the center, so as to easily adapt to different shapes of the human body surface.

[0040] Therefore, the present invention generates an electric field enhancement effect and a micro-discharge increase effect through the magnetic field in the Z-axis direction; and then generates a step-by-step breakdown effect (firstly breaking down the micro-air gaps in the insulating medium), further reducing the discharge distance and enhancing the discharge electric field; at the same time, since the magnetic field can confine electrons in the discharge channel, increasing the micro-discharge effect, the enhanced plasma can still maintain stable and uniform discharge, avoiding the generation of filamentous discharge and causing harm to human tissues. At the same time, the micropores uniformly distributed in the insulating dielectric layer also help to dissociate the discharge channel, generating uniform and stable low-temperature plasma and avoiding the generation of filamentous discharge. It can avoid skin damage and discomfort, remove the bacterial biofilm on the skin / tissue, help generate collagen and elastin, and promote wound blood coagulation, healing, tissue regeneration, skin whitening, freckle removal, etc.

[0041] Although the above description of the illustrative specific embodiments of the present invention is provided for the convenience of those skilled in the art of the present technology to understand the present invention, and it should be clear that the present invention is not limited to the scope of the specific embodiments. For those of ordinary skill in the art of the present technology, as long as various changes are within the spirit and scope of the present invention defined and determined by the appended claims, these changes are obvious, and all inventions and creations using the concept of the present invention are within the scope of protection.

Claims

1. A contact plasma treatment instrument, characterized in that, Comprising: An electrode and magnet module, which is connected to a housing through a flexible connection. A battery management module and a high-voltage excitation module are arranged inside the housing; The electrode and magnet module includes an upper electrode and magnet part and a lower magnet part near the skin end; The upper electrode and magnet part successively includes a first permanent magnet, a first electrolytic iron, and an insulating dielectric layer; the lower magnet part near the skin end includes a second electrolytic iron and a second permanent magnet, which are fixed by an insulating cap of the outer housing; The first electrolytic iron is electrically connected to the hollow spherical electrode through a thread; the insulating dielectric layer has uniform micropores along the Z direction; The insulating dielectric layer is divided into upper and lower layers, and the two layers of dielectrics are installed with a gap to form a micro-air gap; the first permanent magnet is magnetized in the vertical direction to generate a steady magnetic field in the Z-axis direction, which is used to confine electrons and form a micro-discharge channel to enhance the magnetic field effect; The first electrolytic iron has a central first electrolytic iron channel penetrating along the radial direction, and the central channel is connected to the axial channel of the hollow spherical electrode. The hollow spherical electrode has a connection interface on the side, which is connected to the axial channel; a micro-air pump is connected to the hollow spherical electrode interface through a hose; by pumping air with the micro-air pump, the micro-air gap between the two layers of dielectrics passes through the inner air gap of the insulating side wall, and the first electrolytic iron central channel, the hollow spherical electrode axial channel and the hose form an air extraction channel, so that the air pressure in the micro-air gap of the insulating dielectric is lower than the atmospheric pressure, and the discharge electric field strength is enhanced by step-by-step breakdown.

2. The contact plasma therapeutic apparatus according to claim 1, wherein Comprising: The high-voltage excitation module is used to output high-voltage pulses to the high-voltage electrode under the action of a main control signal and a modulation signal, and is electrically connected to the electrode and magnet module; a power display lamp is arranged on the housing; a switch, a display screen, a power adjustment knob, and a charging socket are arranged at the bottom of the housing.

3. The contact plasma therapeutic apparatus according to claim 1, wherein, Comprising: A circular hole is reserved at the central position of the first permanent magnet, so that the other end of the hollow spherical electrode passes through the center of the first permanent magnet; the first electrolytic iron is in direct close contact with the first permanent magnet, and the diameter of the first electrolytic iron is larger than the size of the first permanent magnet.

4. A contact plasma therapeutic apparatus according to claim 1, characterized in that, Comprising: The first permanent magnet is fixed by installing fixing blocks on both sides.

5. The contact plasma therapeutic apparatus according to claim 1, wherein Comprising: The first electrolytic iron also serves as a discharge electrode. The center of the first electrolytic iron has a thread and is electrically connected to the hollow spherical electrode through the thread; the insulating dielectric layer is in close contact with the first electrolytic iron, and an insulating glue is adhered to the lower end of the dielectric layer; the permanent magnet, the first electrolytic iron, and the insulating dielectric are respectively fixed by an insulating protrusion at the upper end of the fan-shaped necking and a lower pressing block.

6. The contact plasma therapeutic apparatus according to claim 1, wherein Comprising: In the upper electrode and magnet, the second permanent magnet, the second electrolytic iron, and the insulating dielectric form an independent sealed space through a pressing block, a fixing block, and an insulating protrusion.

7. The contact plasma therapeutic apparatus according to claim 1, wherein Comprising: When the switch is turned on, the micro-air pump is in a working state and pumps air. The micro-air gap between the two layers of dielectrics passes through the inner air gap of the insulating side wall, and the first electrolytic iron central channel, the hollow spherical electrode axial channel and the hose form an air extraction channel, so that the air pressure in the micro-air gap of the insulating dielectric is lower than the atmospheric pressure.

8. A contact plasma therapeutic apparatus according to claim 1, characterized in that, Comprising: The lower magnet part is fixed by an insulating cap of the outer housing.

9. The contact plasma therapeutic apparatus according to claim 1, characterized in that, Comprising: Under the action of the main control signal, the high-voltage excitation module outputs a rated pulsed high voltage with a certain voltage and frequency after boosting and shaping. The number of output pulses and the pulse width within a unit period of the simultaneously output high-voltage pulses are controlled by the modulation signal; under the action of the main control signal and the modulation signal, the high-voltage excitation module outputs a pulsed high voltage of 2 kV - 9 kV, and the frequency of the modulation signal is adjusted between 10 Hz - 5 kHz.

10. The contact plasma therapeutic apparatus according to claim 1, wherein, Including: The high-voltage excitation module is used to output high-voltage pulses to the high-voltage electrode. One end of the high-voltage electrode has a spherical electrode and is fixed on the first and second insulating brackets; The spherical electrode is tightly connected with a hollow spherical electrode at the lower end. The other end of the hollow spherical electrode at the lower end has a thread and is electrically connected to the first electrolytic iron. The electrode and the shell of the magnet module have a fan-shaped necking. The fan-shaped necking and the shell are integrated through a flexible connection. The electrode and the magnet module can rotate and adjust the position around the hollow spherical electrode, so as to easily adapt to different shapes of the human body surface.

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