CN219935603U - Transdermal diffusion cell - Google Patents

Abstract

The utility model belongs to the field of transdermal test equipment, and particularly discloses a transdermal diffusion cell, which comprises a receiving cell and a supply cell, wherein a skin membrane is arranged between the receiving cell and the supply cell in an isolated manner, the skin membrane is flattened and fixed through a skin fixing frame, the skin fixing frame comprises a plurality of frames which are connected end to end, one side of the frame, which faces the skin membrane, is movably connected with a telescopic structure, the telescopic structure is connected with a clamping structure, the clamping structure clamps the edge of the skin membrane, and the edge of the skin membrane is contracted and approaching to the frame along with the telescopic structure, so that the skin membrane is flattened. The transdermal diffusion cell provided by the utility model is provided with the skin membrane fixing frame, and can be expanded and flattened in all directions by taking the center of the skin membrane as a base point, so that a flattening effect superior to manual stretching is formed, the transdermal effect of a sample on actual skin is more similar, and the problems that in the prior art, the diffusion cell needs to manually flatten the skin membrane, the flattening effect is poor, and the sample permeation is affected are effectively solved.

Description

Transdermal diffusion cell

Technical Field

The present utility model relates to the field of transdermal test devices, and more particularly to a transdermal diffusion cell.

Background

The transdermal diffusion experiment is a process of researching the transdermal absorption efficiency by using skin color permeability to put medicines and cosmetics into a receiving tank through a skin layer, and the experimental method can reflect the speed and degree of permeation of medicines and the like through the skin of an animal living body and screen a transdermal absorption pharmaceutical preparation prescription. The transdermal absorption test using the Franz diffusion cell can reflect the drug release process of the transdermal preparation more objectively.

In recent years, devices for simulating Franz experiments have been improved continuously, but most of the devices adopt a mode of manually expanding a skin membrane and fixing edges after the skin membrane is expanded, so that the skin membrane cannot be effectively flattened, the natural tightening state of human skin cannot be well simulated, and the experimental effect is affected.

Disclosure of Invention

In view of the above, the present utility model provides a transdermal diffusion cell, which is used for solving or partially solving the problems that the existing transdermal diffusion cell on the market cannot automatically flatten the skin membrane, and the flattening effect is poor, so that the sample detection accuracy is affected.

In order to achieve the above purpose, the present utility model provides the following technical solutions:

the utility model provides a transdermal diffusion cell, includes the receiving pool and supplies with the pond, should receive and supply with the pond between the isolation be equipped with the skin membrane, the skin membrane is flattened and fixed through a skin fixed frame, the skin fixed frame includes a plurality of rims that head and tail meet, one side swing joint of frame towards the skin membrane has the extending structure, the extending structure is connected with the clamping structure, the edge of skin membrane is cliied to the clamping structure, is close to along with extending structure to the frame shrink, realizes the exhibition of skin membrane.

According to the transdermal diffusion cell provided by the utility model, the skin membrane fixing frame is arranged, and the skin membrane fixing frame can be expanded and flattened in all directions by taking the center of the skin membrane as a base point, so that a flattening effect superior to manual stretching is formed, the transdermal effect of a sample on actual skin is more similar, and the problems that in the prior art, the skin membrane is required to be flattened manually by the diffusion cell, the flattening effect is poor, and the sample detection accuracy is affected are effectively solved.

Preferably, the telescopic structure is a rhombic telescopic net structure and comprises a plurality of rhombic frames which are sequentially arranged and hinged, and the joints of the sides of the rhombic frames are mutually hinged. Because the telescopic structure adopts the diamond telescopic net structure, not only the stretching force is provided in the stretching direction, but also the expansion force is provided in the direction perpendicular to the stretching direction, the distance between the adjacent clamping structures is also enlarged while the telescopic structure is contracted, the expansion stretching force towards two sides can be formed on the skin membrane from the stretching direction perpendicular to the stretching connecting rod, the whole stretching process takes the center of the skin membrane as a base point, and the flattening process of expanding towards all directions can form a flattening effect superior to manual stretching.

Preferably, the above-mentioned telescopic structure is connected with frame through a stretching connecting rod, one end of the stretching connecting rod is connected with telescopic structure, another end is passed through the frame, and a positioning device is set at the end portion of one passed end so as to maintain the state of simulating skin tightness of human body.

Preferably, the positioning device is an operating handle rotationally connected to the end part of the stretching connecting rod, the operating handle comprises a first supporting leg and a second supporting leg, the first supporting leg and the second supporting leg are arranged at intervals, a U-shaped groove capable of accommodating the frame to enter is formed at the interval position, and the first supporting leg and the second supporting leg can be abutted to the edge of the frame through rotating the operating handle to form shrinkage positioning on the telescopic structure. Based on the structure, the U-shaped groove can be clamped into the edge of the frame by the operating handle, the stretching connecting rod stretches into the frame for a longer length, and the telescopic structure is in an stretching state, namely, a state when the skin membrane is not stretched; the operation handle can also realize that the first supporting leg and the second supporting leg are propped against the edge of the frame, and the length of the stretching connecting rod which is deep into the frame is short at the moment, and the telescopic structure is in a contracted state.

Preferably, a first rubber gasket is interposed between the skin membrane and the supply tank, and a second rubber gasket is interposed between the skin membrane and the receiving tank. The first rubber gasket and the second rubber gasket can strengthen the fitting degree of the skin membrane and the supply tank or the receiving tank, meanwhile, friction is increased, the stretching of the skin membrane by the telescopic structure and the clamping structure is relieved, the edge of the skin membrane is prevented from being torn or damaged, and edge penetration is caused.

Preferably, the top opening of the supply tank is detachably connected with a cover body, and at least one ventilation hole is formed in the cover body.

Preferably, a cover filter membrane is arranged at the air vent, and the cover filter membrane is a ventilation filter membrane with the thickness of 0.45 mu m. The filter membrane has ventilation effect, and can prevent external pollution from entering and prevent the pollution of reagents in the supply tank.

Preferably, a sampling port in the shape of a velvet bottle is formed on one side of the receiving tank, and the sampling port comprises at least one upward bending part, so that a liquid seal is effectively formed, and sample solution pollution and bacterial immersion are avoided.

Preferably, a sample solution filter membrane is further disposed in the receiving tank, and is located above the sampling port, and is used for filtering the sample solution entering the sampling port, and the sample solution filter membrane is a filter membrane of 0.22 μm. The sample liquid filter membrane effectively filters the sample liquid, reduces the secondary treatment of sample preparation, and is convenient for directly detecting the sample solution by a precise instrument.

Preferably, a magnetic stirring device is arranged at the bottom of the receiving tank, the magnetic stirring device comprises an external magnetic field and a stirrer which is arranged in the receiving tank, and the stirrer is driven by the magnetic field to perform circumferential operation in the receiving tank, so that the purpose of stirring the sample solution is achieved.

Drawings

In order to more clearly illustrate the embodiments of the present utility model or the technical solutions of the prior art, the following description will briefly explain the drawings used in the embodiments or the description of the prior art, and it is obvious that the drawings in the following description are some embodiments of the present utility model, and other drawings can be obtained according to these drawings without inventive effort for a person skilled in the art.

FIG. 1 is a schematic view of a transdermal diffusion cell according to the present utility model;

FIG. 2 is a schematic view showing a structure of a skin membrane fixing frame in a transdermal diffusion cell according to the present utility model;

FIG. 3 is an enlarged view at A in FIG. 2;

FIG. 4 is a graph showing the effect of stretching the skin membrane by the skin membrane fixing frame shown in FIG. 2;

FIG. 5 is an enlarged view at B in FIG. 4;

FIG. 6 is a diagram showing the positional relationship between the operating handle and the stretching linkage in the transdermal diffusion cell of the present utility model;

FIG. 7 is a view showing the relationship between the operating handle and the frame when the operating handle is in the second position;

fig. 8 is a positional relationship diagram between the operating handle and the frame when the operating handle is in the first position.

Reference numerals illustrate:

1. a receiving pool; 11. a sampling port; 12. a stirrer;

2. a supply tank; 21. an external thread;

3. a cover body; 31. ventilation holes;

4. a skin membrane fixing frame; 41. a frame; 42. a telescopic structure; 43. a clamping structure; 44. an operation handle; 441. a first leg; 442. a second leg; 443. a hand-held part; 45. stretching the connecting rod;

5. a first rubber gasket;

6. a second rubber gasket;

7. a skin membrane.

Detailed Description

The present utility model will be described more fully hereinafter with reference to the accompanying drawings, in which embodiments of the utility model are shown, and in which embodiments of the utility model are shown, but in which the utility model is not limited to the embodiments shown. All other embodiments, which can be made by those skilled in the art based on the embodiments of the utility model without making any inventive effort, are intended to be within the scope of the utility model.

In the description of the embodiments of the present utility model, it should be noted that the terms "center", "longitudinal", "lateral", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc. indicate orientations or positional relationships based on the orientations or positional relationships shown in the drawings, are merely for convenience in describing the embodiments of the present utility model and simplifying the description, and do not indicate or imply that the apparatus or elements referred to must have a specific orientation, be configured and operated in a specific orientation, and thus should not be construed as limiting the embodiments of the present utility model. Furthermore, the terms "first," "second," and "third" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance.

In describing embodiments of the present utility model, it should be noted that, unless explicitly stated and limited otherwise, the terms "coupled," "coupled," and "connected" should be construed broadly, and may be either a fixed connection, a removable connection, or an integral connection, for example; can be mechanically or electrically connected; can be directly connected or indirectly connected through an intermediate medium. The specific meaning of the above terms in embodiments of the present utility model will be understood in detail by those of ordinary skill in the art.

In embodiments of the utility model, unless expressly specified and limited otherwise, a first feature "up" or "down" on a second feature may be that the first and second features are in direct contact, or that the first and second features are in indirect contact via an intervening medium. Moreover, a first feature being "above," "over" and "on" a second feature may be a first feature being directly above or obliquely above the second feature, or simply indicating that the first feature is level higher than the second feature. The first feature being "under", "below" and "beneath" the second feature may be the first feature being directly under or obliquely below the second feature, or simply indicating that the first feature is less level than the second feature.

In the description of the present specification, a description referring to terms "one embodiment," "some embodiments," "examples," "specific examples," or "some examples," etc., means that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the embodiments of the present utility model. In this specification, schematic representations of the above terms are not necessarily directed to the same embodiment or example. Furthermore, the particular features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples. Furthermore, the different embodiments or examples described in this specification and the features of the different embodiments or examples may be combined and combined by those skilled in the art without contradiction.

The transdermal diffusion cell of the present utility model is described below with reference to fig. 1 to 8.

Referring to fig. 1, fig. 1 shows a schematic structural view of a transdermal diffusion cell according to the present utility model. The transdermal diffusion cell of this embodiment is used for skin absorption in vitro experiments, this transdermal diffusion cell can include receiving cell 1, supply cell 2, receiving cell 1 top opening, inside is used for holding sample solution, the lateral part is opened sampling port 11, supply cell 2 is located and is received cell 1 top, have the bottom opening of receiving cell 1 top opening adaptation, be used for to receiving cell 1 permeable, supply cell 2 top is the same opening, be used for filling reagent, in order to prevent reagent volatilize and pollute, be equipped with detachable lid 3 at the top of supply cell 2, and open at least one bleeder vent 31 on lid 3, place skin membrane 7 between receiving cell 1 and supply cell 2, skin membrane 7 can be selected from the mouse skin or pig skin etc. skin, skin membrane 7 needs to flatten, in order to simulate the state that human skin is tight, in this embodiment, skin membrane fixed frame 4 is used for realizing the fixed stretching to skin membrane 7, this skin membrane fixed frame 4 includes frame 41, and connect at least two sets of stretching components in frame 41, two sets of stretching components correspond to setting up, from skin membrane 7 two opposite edges, and the operation of the back membrane 7 is carried out to skin membrane 7.

Specifically, as shown in fig. 2 and 3, in the present embodiment, the stretching assembly includes a telescopic structure 42, a clamping structure 43, an operation handle 44, and a stretching link 45; the telescopic structures 42 are diamond-shaped telescopic net structures, and comprise a plurality of diamond-shaped frames which are sequentially arranged and hinged, all sides of the diamond-shaped frames are mutually hinged, one side (inner side) of each telescopic structure 42 far away from the frame 41 is connected with the clamping structures 43, in the embodiment, each telescopic structure 42 is connected with four clamping structures 43, and the clamping can be formed on one side edge of the skin membrane 7 more uniformly; the stretching connecting rod 45 goes deep into the middle of the stretching structure 42, one end of the stretching connecting rod is connected with the inner side of the stretching structure 42, the other end of the stretching connecting rod penetrates through the frame 41 and penetrates out of the outer side of the frame 41, the end of the stretching connecting rod is rotatably connected with the operating handle 44, the operating handle 44 is used for pulling the stretching connecting rod 45, further stretching control of the stretching structure 42 is achieved, the stretching connecting rod is rotationally fixed after being pulled to a certain position, and as shown in fig. 4 and 5, after the skin membrane 7 is clamped, the skin membrane 7 is flattened and stretched through the operating handle 44 of the stretching assembly.

Specifically, as shown in fig. 6 to 8, the operation handle 44 and the stretching linkage 45 are schematic structural diagrams, the operation handle 44 includes a first leg 441, a second leg 442, and a hand-hold portion 443, the first leg 441 and the second leg 442 are integrally formed and fixedly connected with the hand-hold portion 443, a U-shaped groove capable of accommodating the frame 41 is formed between the first leg 441 and the second leg 442, the width of the U-shaped groove (i.e. the distance from the first leg 441 to the second leg 442) is greater than or equal to the thickness of the frame 41, and the end of the stretching linkage 45 is rotatably connected to the bottom of the U-shaped groove of the operation handle 44; based on the above structure, the operation handle 44 can realize the first position shown in fig. 8, in which the U-shaped groove is clamped into the edge of the frame 41, and at this time, the stretching connecting rod 45 is deep into the frame 41, and the stretching structure 42 is in the stretched state, that is, the state when the skin membrane 7 is not stretched in fig. 2; the operating handle 44 may further realize a second position shown in fig. 7, in which the first leg 441 and the second leg 442 abut against the edge of the frame 41, and the stretching linkage 45 extends into the frame 41 to a short length, and the telescopic structure 42 is in a contracted state, i.e. a state after stretching the skin membrane 7 in fig. 4.

The transdermal diffusion cell based on the structure can be used for rapidly flattening the skin membrane 7, and the flattening effect is good, as the telescopic structure 42 adopts the diamond telescopic net structure, not only is the stretching direction of the stretching connecting rod 45 provided with a pulling force, but also the distance between the adjacent clamping structures 43 is enlarged when the telescopic structure 42 is contracted, the stretching force to two sides can be formed on the skin membrane 7 from the stretching direction perpendicular to the stretching connecting rod 45, the whole stretching process takes the center of the skin membrane 7 as a base point, and the flattening process of expanding in all directions can form flattening effects superior to manual stretching, and meanwhile, the skin membrane 7 can be prevented from being broken, after the skin membrane 7 is well flattened, the transdermal effect of a sample on actual skin is more similar, and the detection accuracy can be obviously improved naturally.

Further, the skin membrane fixing frame 4 has a square shape, and a stretching assembly is provided in each frame 41 to uniformly apply stretching force to the skin membrane 7 from four directions.

Further, the diamond-shaped telescopic net of the side, close to the frame 41, of the telescopic structure 42 is slidably connected with the frame 41, specifically, a sliding groove is formed in the inner side of the frame 41, a plurality of sliding blocks are arranged on the diamond-shaped telescopic net of the side, close to the frame 41, of the telescopic structure 42, the sliding blocks are slidably connected in the sliding groove, and the sliding connection mode is adopted to guide the trend of the telescopic structure 42 in the direction perpendicular to the stretching direction, so that the stability of the telescopic structure 42 is improved.

It will be appreciated that the stretching linkage 45 is used to change the stretching state of the stretching structure 42, so other structures that can change the stretching state of the stretching structure 42 through rotation or stretching action can be used as the replacing structure of the stretching linkage 45 in this embodiment, such as a screw, where one end of the screw is rotatably connected to the stretching structure 42 and the other end is in threaded connection with the frame 41 when the screw is used to connect the stretching structure 42 and the frame 41, and the length of the screw screwed into the frame 41 can be changed through rotation, so as to change the stretching state of the stretching structure 42.

In the present embodiment, the structure using the operation handle 44 and the stretching linkage 45 has the advantage of simple operation, and by pulling the operation handle 44 and then changing (rotating) the direction of the operation handle 44, the telescopic structure 42 can be contracted and positioned without complicated rotational stretching and positioning as compared with the screw.

It should be further understood that the skin membrane fixing frame 4 may be circular, and the telescopic structure 42 may be other components having expansion and contraction functions, which will not be described herein.

Further, in order to ensure the tightness of the skin membrane 7 pressed in the middle after the receiving tank 1 and the supplying tank 2 are connected, the fitting degree of the skin membrane 7 with the receiving tank 1 and the supplying tank 2 is increased, rubber gaskets are padded on the upper surface and the lower surface of the skin membrane 7, namely, a second rubber gasket 6 is padded on the upper opening position of the receiving tank 1, and a first rubber gasket 5 is padded on the lower opening position of the supplying tank 2; the first rubber gasket 5 and the second rubber gasket 6 can strengthen the fitting degree of the skin membrane 7 and the upper vessel and the lower vessel (the supply tank 2 and the receiving tank 1), increase friction at the same time, relieve the dragging of the telescopic structure 42 and the clamping structure 43 to the skin membrane, and avoid the edge tearing or damage of the skin membrane 7, so as to cause edge penetration.

Further, a cover filter membrane with the thickness of 0.45 μm is arranged at the vent hole 31 of the cover 3, and the filter membrane has a ventilation effect and can prevent external pollution from entering and prevent the pollution of the reagent in the supply tank 2.

Further, the cover body 3 and the supply tank 2 can adopt a flip cover or a screw cover, for example, a screw cover is taken as an example, internal threads are arranged in the cover body 3, external threads 21 are arranged at the upper edge of the supply tank 2, and the cover body 3 is screwed on the supply tank 2, so that the tightness is ensured, and the cover body 3 is prevented from being knocked over in the operation process.

Furthermore, the receiving tank 1 is embedded with a 0.22 mu m sample liquid filter membrane, so that sample liquid is effectively filtered, secondary treatment of sample preparation is reduced, and accurate instrument detection, such as liquid phase detection, is conveniently and directly carried out on sample solution.

Further, sample liquid filter membrane is placed in receiving tank 1 through a fixed splint, and fixed splint includes two-layer, and the lower floor is fixed in receiving tank 1, and the upper strata is adjustable, and sample liquid filter membrane presss from both sides and puts between two-layer splint, because of simple structure, does not influence understanding, and this fixed splint is not shown in the figure, and above-mentioned fixed splint's upper strata is adjustable, is convenient for change the filter membrane.

Further, the sampling port 11 is a swan neck bottle structure, and has at least one upward bending part, so that a liquid seal is effectively formed, and sample solution pollution and bacterial immersion are avoided.

Further, the transdermal diffusion cell further comprises a magnetic stirring device arranged at the bottom of the receiving cell 1, wherein the magnetic stirring device comprises an external magnetic field and a stirrer 12 arranged in the receiving cell 1, and the stirrer 12 is driven by the magnetic field to perform circumferential operation in the receiving cell 1, so that the purpose of stirring a sample solution is achieved.

In other embodiments, the first leg 441 and the second leg 442 are integrally formed, a U-shaped slot capable of accommodating the frame 41 is formed between the two legs, the combination of the first leg 441 and the second leg 442 is separated from the hand-hold portion 443, a through hole is formed in the center of the bottom of the U-shaped slot, the stretching connecting rod 45 passes through the rear end of the through hole and is fixedly connected to the hand-hold portion 443, and may be integrally formed with the hand-hold portion 443, at this time, the first leg 441 and the second leg 442 together form an independent component, the hand-hold portion 443 and the stretching connecting rod 45 together form another independent component, and the two components are connected in a plugging manner, when in use, the hand-hold portion 443 cannot rotate due to the fixed connection of the hand-hold portion 443, and the combination of the first leg 441 and the second leg 442 can be independently rotated to complete the switching from the first position to the second position.

When the transdermal diffusion cell is used, the transdermal diffusion cell can be matched with a water bath kettle to be used, a plurality of transdermal diffusion cells are placed in the water bath kettle, and a heating temperature control system is matched to maintain the temperature environment required by experimental conditions.

Compared with the traditional transdermal diffusion cell, the transdermal diffusion cell provided by the utility model is provided with the skin membrane fixing frame, and can be expanded and flattened in all directions by taking the center of the skin membrane as a base point, so that a flattening effect superior to manual stretching is formed, and the transdermal effect is further improved; the bottom of the receiving tank is also provided with a magnetic stirring device, so that the sample solution can be sufficiently stirred in a relatively closed space; a sampling port of a velvet bottle structure is formed in the side part of the receiving tank, so that the sample can be conveniently sampled, and meanwhile, the pollution of a sample solution and the bacterial immersion can be avoided.

It will be understood that the utility model has been described in terms of several embodiments, and that various changes and equivalents may be made to these features and embodiments by those skilled in the art without departing from the spirit and scope of the utility model. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the utility model without departing from the essential scope thereof. Thus, various changes and modifications to the disclosed features and combinations of features not explicitly shown herein may be made by those skilled in the art within the scope of the utility model. The foregoing description of the embodiments and examples are illustrative rather than limiting.

Claims (10)

1. The utility model provides a transdermal diffusion cell, includes receiving pool (1) and supplies pond (2), its characterized in that, keep apart between receiving pool (1) and supplying pool (2) and be equipped with skin membrane (7), skin membrane (7) are flattened and fixed through a skin fixed frame (4), skin fixed frame (4) include a plurality of end to end's frame (41), frame (41) orientation one side swing joint of skin membrane (7) has extending structure (42), extending structure (42) are connected with clamping structure (43), clamping structure (43) are cliied skin membrane (7)'s edge, along with extending structure (42) to frame (41) shrink is close to, realizes to skin membrane (7)'s flattening.

2. A transdermal diffusion cell according to claim 1, wherein the telescopic structure (42) is a diamond-shaped telescopic net structure comprising a plurality of diamond-shaped elements which are arranged in sequence and hinged, and the connection of the edges of the diamond-shaped elements are hinged to each other.

3. A transdermal diffusion cell according to claim 2, wherein the telescopic structure (42) is connected to the frame (41) by a tension link (45), one end of the tension link (45) is connected to the telescopic structure (42), the other end extends through the frame (41), and positioning means are provided at the end extending through one end.

4. A transdermal diffusion cell according to claim 3, wherein the positioning means is an operating handle (44) rotatably connected to the end of the stretching rod (45), the operating handle (44) comprises a first leg (441) and a second leg (442), the first leg (441) and the second leg (442) are spaced apart, a U-shaped groove for accommodating the frame (41) is formed at a spaced position, and the first leg (441) and the second leg (442) can be abutted against the edge of the frame (41) by rotating the operating handle (44) to form a contracted positioning for the telescopic structure (42).

5. A transdermal diffusion cell according to claim 1, characterized in that a first rubber gasket (5) is padded between the skin membrane (7) and the supply cell (2), and a second rubber gasket (6) is padded between the skin membrane (7) and the receiving cell (1).

6. A transdermal diffusion cell according to claim 1, wherein the top opening of the supply cell (2) is detachably connected with a cover (3), and at least one ventilation hole (31) is formed in the cover (3).

7. The transdermal diffusion cell according to claim 6, wherein a cover filter membrane is provided at the ventilation hole (31), and the cover filter membrane is a ventilation filter membrane of 0.45 μm.

8. A transdermal diffusion cell according to claim 1, wherein a sampling port (11) in the shape of a velvet-neck bottle is provided on one side of the receiving cell (1), the sampling port (11) comprising at least one upward bend.

9. The transdermal diffusion cell according to claim 8, wherein a sample solution filter membrane is further placed in the receiving cell (1), the sample solution filter membrane is located above the sampling port (11), and is used for filtering the sample solution entering the sampling port (11), and the sample solution filter membrane is a filter membrane of 0.22 μm.

10. The transdermal diffusion cell according to claim 4, wherein the bottom of the receiving cell (1) is provided with a magnetic stirring device, the magnetic stirring device comprises an external magnetic field and a stirrer (12) arranged in the receiving cell (1), and the stirrer (12) is driven by the magnetic field to perform circumferential operation in the receiving cell (1).