Fluid memristor based on tesla valve structure

Abstract

The application discloses a fluid memristor based on a Tesla valve structure and belongs to the field of fluid transmission and micro-fluidic technology. At least one Tesla valve flow channel unit is formed in a flow channel base body, and the wall surfaces of the flow channel base body and the Tesla valve flow channel unit are all rigid structures which cannot be deformed. The Tesla valve flow channel unit comprises a main flow channel and at least one reflux bypass which is in fluid communication with the main flow channel. In forward flow, the fluid is allowed to pass through the main flow channel mainly and there is no resident vortex in the bypass, and in reverse flow, the fluid is forced to enter the bypass and induce a vortex structure which has a tendency to be maintained. The generation, maintenance and decay process of the vortex structure has path dependence on the flow history, so that the flow-pressure characteristic of the Tesla valve flow channel unit under the driving of an alternating pressure difference presents a memristive pinched hysteresis loop. The application provides a fluid memristor which is extremely simple in structure, passive and full-flow.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of fluid transmission and microfluidics, and particularly relates to a fluid memristor based on a Tesla valve structure. BACKGROUND

[0002] As the fourth basic circuit element, the core characteristic of a memristor is that the resistance of the device depends on the historical charge or magnetic flux flowing through it. By extending the concept of memristor to fluid systems, a fluid memristor can be constructed to realize the memory, logic operation and adaptive adjustment of fluid without relying on electronic control. Most existing fluid memristors store flow history by integrating movable structures such as elastic membranes, flexible cavities or liquid-liquid interfaces, and use mechanical deformation or mass migration to store flow history, but there are problems such as complex structure, limited fatigue life and dynamic response restricted by material viscoelasticity.

[0003] A Tesla valve is a classic fluid diode without moving parts, which is composed of a main flow channel and a bypass in series. When the fluid enters in the forward direction, most of it advances along the main flow channel with a small pressure drop; when the fluid enters in the reverse direction, it is forced to enter the curved bypass due to geometric induction, and a strong separation vortex is formed in the bypass, causing significant energy dissipation and high pressure drop. This bidirectional asymmetric characteristic generated purely by the flow channel geometry and fluid inertia makes the structure extremely reliable, and it has been applied in the fields of micro-mixers and one-way valves. However, so far, the Tesla valve has only been regarded as a two-terminal element without memory, and the flow history dependence of its internal vortex structure has not been used to construct a memristor function.

[0004] If the vortex generated in the reverse flow of the Tesla valve can be used as a kind of "internal state" that can be retained and changed, and the hysteresis effect in the generation and annihilation process is used, then the Tesla valve can be given the characteristic of a memristor without introducing any moving parts or heterogeneous materials, which will greatly expand its application potential in all-fluid intelligent systems. SUMMARY

[0005] The purpose of the present application is to overcome the limitation that existing fluid memristors must rely on elastic or movable parts, and to provide a fluid memristor based on a Tesla valve structure. The device is composed only of a Tesla valve unit, and relies on the inertial vortex dynamics of the fluid itself to achieve stable memristor effect, thereby maintaining the inherent advantage of no moving parts.

[0006] The specific technical solution is as follows:

[0007] A fluid memristor based on a Tesla valve structure, comprising: a rigid base body, at least one Tesla valve flow channel unit is arranged in the rigid base body, the wall surfaces of the flow channel base body and the Tesla valve flow channel unit are all rigid structures that cannot be deformed; the flow channel base body is made of rigid materials such as silicon, glass, metal, hard polymer or ceramic, and the entire device does not have any elastic deformable parts.

[0008] The Tesla valve flow channel unit includes a main flow channel and at least one return bypass connected to the main flow channel. The geometry of the return bypass is configured such that when the fluid flows forward along the inlet to outlet direction of the main flow channel, the main flow channel preferentially guides the flow, and the return bypass basically does not generate stagnant vortices; when the fluid flows backward along the outlet to inlet direction, the return bypass forces the fluid to turn sharply and induces at least one vortex structure with significant intensity and a tendency to be maintained.

[0009] During the generation, enhancement, and decay of the vortex structure, there exists a hysteresis path that depends on the flow history and fluid inertia effect. This results in the transient flow resistance being related to the flow direction and rate of change when alternating positive and negative pressure differentials are applied. The overall flow-pressure relationship of the device exhibits a hysteresis loop that passes through zero, thus demonstrating memristor characteristics.

[0010] Furthermore, the walls of the recirculation bypass are entirely rigid and non-deformable, and the memory effect is entirely achieved by the dynamic hysteresis of the vortex structure itself. Preferably, the geometric parameters and operating Reynolds number of the Tesla valve flow channel unit satisfy the following: during reverse flow, at least one separation vortex is formed in the recirculation bypass, and when the reverse pressure difference decreases or is removed, the separation vortex does not disappear immediately, but is maintained for a period of time with decaying angular momentum, thus constituting a "memory" of the fluid state. When a forward pressure difference is subsequently applied, the residual vortex is pushed into the main flow channel and temporarily increases the forward flow resistance until the vortex energy is completely dissipated. In this way, under periodic pressure drive, the flow resistance values ​​are different during pressure increase and decrease, and during forward and reverse transitions, forming a loop of memristor characteristics.

[0011] The connection angle, bypass length, and cross-sectional dimensions of the main flow channel and the return bypass of the Tesla valve flow channel unit are configured such that, within the range of the fluid used and a predetermined Reynolds number, at least one separation vortex is generated in the bypass during reverse flow, and the decay time constant of the separation vortex after the removal of the reverse driving force is greater than the time scale of the driving pressure change.

[0012] In a preferred embodiment, the main flow channel and the return flow bypass can be obtained through micromachining in a plane, and the entire flow channel is a rigid structure. The material can be silicon, glass, hard polymer, or metal. The main flow channel and the return flow bypass have micron- or millimeter-level feature dimensions and are formed through micromachining, precision machining, or additive manufacturing processes.

[0013] To enhance the timescale and hysteresis area of ​​the memory effect, multiple Tesla valve flow channel units can be integrated into the same flow channel matrix in series, parallel, or a combination of series and parallel connections, so that the multi-stage eddies work together to enhance the intensity of the memristor effect or adjust the shape of the hysteresis curve.

[0014] The recirculation bypass is arc-shaped, zigzag-shaped, or stepped to facilitate the stability and maintenance of the eddy current.

[0015] The present invention also provides a fluid logic circuit comprising at least one fluid memristor based on a Tesla valve structure.

[0016] The present invention also provides a fluid oscillator comprising a fluid memristor based on the Tesla valve structure described above and a fluid capacitive or inductive element connected in series or parallel therewith.

[0017] This invention discloses a fluid memristor based on a Tesla valve structure, consisting solely of the Tesla valve flow channel, requiring no moving parts or elastic deformation elements. It utilizes the unique bidirectional asymmetric flow channel configuration of the Tesla valve: during forward flow, the fluid primarily flows along the low-resistance main channel; during reverse flow, the fluid is forced into the return bypass, generating a strong and persistent vortex structure. The generation, maintenance, and annihilation of these vortices exhibit path dependence on the flow history, resulting in a hysteresis loop-like memristor behavior in the flow-pressure characteristics of the device under alternating flow conditions. This invention fully inherits the advantage of the Tesla valve in achieving complex fluid manipulation without moving parts, providing an extremely simple, fully passive, full-channel fluid memristor that can be widely applied in pure fluid logic circuits, adaptive flow distribution networks, and soft robot control.

[0018] Compared with the prior art, the present invention has the following outstanding advantages:

[0019] Completely without moving parts: The entire fluid memristor is just a rigid cavity with a specific shape, without any elastic membrane, cantilever beam or moving interface, inheriting the high reliability, unlimited life and maintenance-free characteristics of Tesla valve.

[0020] Intrinsic full-channel memory: For the first time, inertial eddy current hysteresis within an indeformable channel is used as a physical memory mechanism to realize memristor functionality in pure fluid dynamics, laying the component foundation for full-fluid computing and storage.

[0021] The structure and process are highly simplified: the flow channel can be formed in one step by processes such as planar photolithography, wet etching, micro-injection molding or 3D printing, without the need to align the bonding elastic layer or fill special media, resulting in extremely low manufacturing cost and excellent repeatability.

[0022] The system offers a wide range of designable characteristics: by changing the bypass length, bend curvature, cross-sectional aspect ratio, and the number of parallel / series flow channels, the threshold pressure, memory retention time, and on / off ratio of the memristor loop can be systematically adjusted to adapt to different application scenarios.

[0023] Wide compatibility with working media: Since there are no special material limitations, it can be used with a variety of Newtonian fluids such as water, oil, and air, and the memristor effect can be achieved within a certain Reynolds number range. Attached Figure Description

[0024] Figure 1 This is a top view of a single Tesla valve memristor unit in the first embodiment of the present invention.

[0025] Figure 2 One of the schematic diagrams showing the streamline distribution of a single Tesla valve memristor unit during forward flow;

[0026] Figure 3 The second schematic diagram shows the streamline distribution of a single Tesla valve memristor unit during forward flow.

[0027] Figure 4 One of the schematic diagrams showing the streamline distribution of a single Tesla valve memristor unit during reverse flow;

[0028] Figure 5 The second schematic diagram shows the streamline distribution of a single Tesla valve memristor unit during reverse flow.

[0029] Figure 6 This study examines the variation of the flow-pressure curve with frequency obtained from numerical simulation under periodic alternating pressure difference. Detailed Implementation

[0030] Example 1:

[0031] like Figure 1 As shown, the Tesla valve-based fluid memristor of this embodiment comprises a silicon substrate in which a closed Tesla valve channel is formed by deep reactive ion etching. The channel height is 80 micrometers and the width is 100 micrometers. The Tesla valve channel includes a straight main channel and four arc-shaped return bypasses at approximately 45° angles to the main channel. All walls are rigid silicon surfaces. The inlet and outlet are connected to external fluid lines. The working fluid is deionized water, and the pressure difference ΔP and flow rate Q between the inlet and outlet are controlled.

[0032] In forward flow (from inlet to outlet), such as Figure 2 and Figure 3 As shown in the schematic diagram of streamline distribution during forward flow, numerical simulation results show that there are no eddies in the recirculation bypass, and the resistance to liquid flow is small. Under the influence of fluid inertia, most of the water flows smoothly along the main channel, and a very weak induced flow is formed in the recirculation bypass, but no stable eddies exist. The flow resistance of the entire device is low and close to constant, and the corresponding flow-pressure curve is approximately linear.

[0033] In reverse flow (flowing in from the outlet and out from the inlet), such as Figure 4 and Figure 5As shown in the schematic diagram of streamline distribution during reverse flow, numerical simulation results reveal the formation of a strong vortex structure within the recirculation bypass, resulting in significant resistance to liquid flow. The main flow in the reverse channel is intercepted, forcing the water into each recirculation bypass. Within each recirculation bypass, abrupt expansion of the channel cross-section and sharp directional changes induce large-scale separation vortices. These vortices cause intense energy dissipation, making the reverse flow resistance significantly higher than the forward flow resistance, exhibiting the classic diode characteristics of a Tesla valve.

[0034] The key to this invention lies in the transient operating condition: after the reverse pressure difference ΔP_rev is maintained for a period of time to allow the vortex to fully develop, the pressure difference is quickly switched to the forward direction. At this time, the vortex does not disappear immediately, but as an inertial structure with momentum and angular momentum, it requires a finite amount of time for viscous decay to completely annihilate. Applying a forward pressure difference during the vortex residue period will drive the residual vortex into the main flow channel, disturbing the forward flow field and causing a temporary increase in forward flow resistance; after the vortex is completely dissipated, the forward flow resistance gradually decreases to a steady state. Conversely, directly reversing from the forward steady state, the establishment of reverse flow resistance is also delayed because it takes time to build up a sufficiently strong vortex in the bypass.

[0035] When an alternating pressure differential with periodically varying amplitude (e.g., sinusoidal pressure) is applied, the hysteresis of eddy generation / annihilation causes the transient flow-pressure points to not coincide during pressure rise and fall, and during forward and reverse transitions, resulting in conditions such as... Figure 6 The stable hysteresis loop is shown. The flow-pressure curve measured by numerical simulation under periodic alternating pressure difference exhibits the following variation with frequency: Under quasi-static pressure conditions, the system behaves like a fluid diode with rectification function; under mid-frequency conditions, the system exhibits a typical memristor hysteresis loop, and the flow extremum decreases with increasing external pressure frequency; under high-frequency conditions, the system behaves like a fluid capacitor. This loop passes through the origin, and its shape and area vary with the driving frequency and amplitude, conforming to the definition characteristics of a memristor. Therefore, this fully rigid Tesla valve structure constitutes a novel fluid memristor.

[0036] Example 2:

[0037] To further improve memory strength and loop-on ratio, this embodiment arranges multiple identical Tesla valve memristor units in a series array according to their flow channels. The outlet of each stage serves as the inlet of the next stage, and all flow channels are micro-milled onto a single rigid polymethyl methacrylate (PMMA) substrate. After cascading, the vortex groups generated by the reverse flow at each stage superimpose, significantly enhancing the overall hysteresis effect. The measured hysteresis curve area increases to several times that of a single stage, making it suitable for constructing fluid oscillators and memory units.

[0038] It should be noted that the above embodiments are for illustrative purposes only and do not constitute a limitation on the scope of protection. For those skilled in the art, based on the principles of this invention, various equivalent structures can be derived by optimizing the geometry, flow channel topology, and fluid properties.

Claims

1. A fluid memristor based on a Tesla valve structure, characterized in that, include: The flow channel matrix has at least one Tesla valve flow channel unit formed within it, and the walls of both the flow channel matrix and the Tesla valve flow channel unit are rigid structures that cannot be deformed. The Tesla valve flow channel unit includes a main flow channel and at least one return bypass fluidly connected to the main flow channel. The geometry of the return bypass is configured such that, during forward flow, the fluid is allowed to pass mainly through the main flow channel and there are no stagnant vortices in the bypass, while during reverse flow, the fluid is forced into the bypass and induces a vortex structure with a tendency to sustain. The generation, maintenance, and decay processes of the vortex structure are path-dependent on the flow history, causing the flow-pressure characteristics of the Tesla valve flow channel unit under alternating pressure differential to exhibit a memristor hysteresis loop.

2. A fluid memristor based on a Tesla valve structure according to claim 1, characterized in that, The flow channel matrix is ​​made of silicon, glass, metal, hard polymer or ceramic.

3. A fluid memristor based on a Tesla valve structure according to claim 1, characterized in that, The connection angle, bypass length, and cross-sectional dimensions of the main flow channel and the return bypass of the Tesla valve flow channel unit are configured such that, within the range of the fluid used and a predetermined Reynolds number, at least one separation vortex is generated in the bypass during reverse flow, and the decay time constant of the separation vortex after the removal of the reverse driving force is greater than the time scale of the driving pressure change.

4. A fluid memristor based on a Tesla valve structure according to claim 1, characterized in that, The Tesla valve flow channel units are multiple and are integrated in the same flow channel matrix in a series, parallel, or mixed series-parallel manner.

5. A fluid memristor based on a Tesla valve structure according to claim 1, characterized in that, The reflux bypass is arc-shaped, zigzag-shaped, or stepped.

6. A fluid memristor based on a Tesla valve structure according to claim 1, characterized in that, The main flow path and the return flow bypass have micron- or millimeter-level feature dimensions and are formed through micromachining, precision machining, or additive manufacturing processes.

7. A fluid logic circuit, characterized in that, It includes at least one fluid memristor based on a Tesla valve structure according to any one of claims 1 to 6.

8. A fluid oscillator, characterized in that, It includes a fluid memristor based on a Tesla valve structure according to any one of claims 1 to 6, and a fluid capacitive or inductive element connected in series or parallel therewith.

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