WO2012136377A1

WO2012136377A1 - Probe shaped in order to move in a fluid-filled volume and process for moving such a probe

Info

Publication number: WO2012136377A1
Application number: PCT/EP2012/001537
Authority: WO
Inventors: Gilgueng Hwang; Dogan Sinan Haliyo; Stéphane Regnier
Original assignee: Universite Pierre Et Marie Curie (Paris 6); Centre National De La Recherche Scientifique
Priority date: 2011-04-07
Filing date: 2012-04-06
Publication date: 2012-10-11
Also published as: FR2973682A1

Abstract

The invention relates to a probe shaped in order to move in a fluid-filled volume, for example a blood vessel (10). According to the invention, the probe is at least partly covered with a layer of hydrophobic material (40). The invention also relates to a process for moving such a probe.

Description

Shaped probe for moving in a volume filled with fluid and method for moving such a probe

The invention relates to a probe shaped to move in a volume filled with fluid, for example a blood vessel. The invention also relates to a method for moving such a probe.

BACKGROUND OF THE INVENTION

In the medical field, many researches have been carried out for some years on probes intended to move in parts of the human body such as blood vessels, ducts of the digestive system ... It is envisaged to use these probes to perform acts localized medical conditions. For example, a probe travels to an area of the human body with cancerous cells and delivers directly to said cells a chemotherapy treatment. This would be more effective and less restrictive for a patient than a radiotherapy treatment or even a conventional chemotherapy treatment. Another example of application relates to the unblocking of a partially obstructed artery.

In general, these probes are shaped to mimic as much as possible the shape of a bacterium. Indeed, a bacterium moves very quickly in a fluid, even very viscous, especially thanks to its flagellum. Thus, as illustrated in Figure 1, a probe developed by the Institute of Robotics and Intelligent Systems IRIS (probe presented on a page of the IRIS website at http: // www.iris.ethz. ch / msrl / research / micro / helical_swimmer s /) comprises a magnetic head 1 and a tail 2 which is shaped in the form of a substantially circular helix, the tail 2 reproducing a flagellum of a bacterium. A rotating magnetic field causes a rotation of the tail 2 and thus causes a displacement of the probe in water.

It is recalled that a circular helix is included in a cylinder of revolution. A circular propeller is characterized by its axis and radius (those of the cylinder), its winding direction and pitch.

However, it turns out that current probes, including the IRIS probe, move with difficulty in viscous fluids. They could not move in the human body because of the viscous nature of body fluids.

Moreover, a large part of the probes of the prior art, including the IRIS probe, are displaced by a magnetic field. However, the probes must absolutely include a magnetic head.

OBJECT OF THE INVENTION

The object of the invention is to provide a shaped probe to be able to move easily in a volume filled with fluid even viscous.

BRIEF DESCRIPTION OF THE INVENTION

For the purpose of achieving this goal, there is provided a probe shaped to move in a volume filled with fluid, for example a blood vessel, the probe being covered at least in part with a layer of hydrophobic material. According to the invention, the hydrophobic material is graphene.

The inventors have thus found that the probe of the invention moved more easily in a very viscous fluid than a probe of the prior art. Indeed, the fluid slides more easily on a surface of the probe through the layer of hydrophobic material which reduces the friction forces to which the probe is subjected when it advances in the fluid.

In addition, extremely advantageously, graphene turns out to be a very stable material so that the probe, thus covered with a graphene layer, oxidizes very slowly. The probe is therefore significantly less toxic than a probe with no graphene layer or even a probe with only one layer hydrophobic material other than graphene. In addition, even in very thin layer, graphene has a large hydrophobic character. The probe of the invention can thus be of small size, the graphene layer being of a thickness of only a few atoms and still moving very easily in sometimes very viscous fluids.

A probe according to the invention covered at least in part with a layer of graphene hydrophobic material is thus particularly suitable for moving in a highly viscous fluid having a Reynolds number of less than 0.1.

The invention also relates to a method for moving such a probe. Said method comprises the step of creating in the fluid an electric field under the action of which the probe moves in the volume filled with fluid.

By a so-called electro-osmosis phenomenon, the application of an electric field moves free charges present in a diffuse layer of said fluid, the diffuse layer being the layer which is in contact with the surface of the probe. The movement of these free charges, via viscous bonds, then causes a corresponding movement of the diffuse layer. The probe is then propelled in a direction opposite to the movement of the diffuse layer. Thus, by controlling the electric field, it is possible to manage the direction and the speed of the displacement of the probe.

The inventors have observed that the hydrophobic material layer makes it possible to amplify the phenomenon of electroosmosis and thus facilitates the displacement of the probe in the fluid volume. In addition, the probe can be very simple to manufacture and be for example simply shaped in the form of warhead contrary to the probes of the prior art which must have a head to be movable by a magnetic field.

Experiments have thus shown that by combining the electric field and the hydrophobic material layer, the speed of the probe of the invention can rise up to twenty-four times the length of the probe per second in the water. No other probe of the prior art or even any known bacteria moves at such a rate.

BRIEF DESCRIPTION OF THE DRAWINGS

Figure 1 has already been described and illustrates a probe of the prior art.

The invention will be better understood in the light of the following description of a particular non-limiting embodiment of the invention with reference to the attached figures among which:

- Figure 2 is a schematic sectional view of a probe according to the invention in displacement in a conduit filled with fluid;

- Figure 3 is a schematic sectional view of a probe according to another embodiment of the invention moving in a conduit filled with fluid.

DETAILED DESCRIPTION OF THE INVENTION

According to the invention, a probe shaped to move in a volume filled with fluid is covered at least in part by a layer of hydrophobic material. To move said probe in the fluid volume, an electric field is created which sets free charges present in a diffuse layer of the fluid surrounding the probe. This causes a displacement of the diffuse layer in one direction and thus a displacement in the opposite direction of the probe.

The layer of hydrophobic material allows all of the following: Isolate the probe from surrounding fluid to delay and minimize oxidation of the probe by the fluid. Indeed, such oxidation causes destruction of the probe and contamination of the fluid by the probe.

Facilitate the displacement of the probe in the fluid volume by reducing the frictional forces to which the probe is subjected as it moves through the fluid.

Amplify the phenomenon of electroosmosis at the origin of the displacement of the probe and thus further facilitate the displacement of the probe in the fluid.

The table below compares various characteristics of a probe of the prior art comprising a helix and a probe according to the invention strictly identical to the probe of the prior art apart from the fact that its helix is coated with a layer of hydrophobic material.

Probe art Probe according

previous invention

about 20 to 60 nanometers (depending

Dimension

about 20 the transverse method of the

nanometers depositing the probe layer

hydrophobic material)

Amplitude of

oscillations of the

tail (for about 25 about 46 micrometers electric field micrometers

100 Volt / meter - 1

Hertz)

Frequency of Very low High frequency frequency rotation (or (up to about tail (for less than 20 Hertz) 50 Hertz) electric field of

100 Volt / meter - 1

Hertz)

No destruction

Lifetime (in

1 to 2 days of the probe by the water)

the water.

biocompatibility

with a fluid No Yes

organic

It is thus clearly visible that the layer of hydrophobic material facilitates the displacement of the probe (the amplitude of the oscillations and the frequency of rotation of the tail of the probe according to the invention being much better) and limits the destruction of the probe by the water. The values are given by way of example for a particular embodiment of the invention and are therefore not limiting.

According to the invention, the layer of hydrophobic material is graphene which has many advantages.

Graphene turns out to be a very stable material so that the probe, thus covered with a layer of graphene, oxidizes very slowly. The probe is therefore significantly less toxic than a probe having no layer of hydrophobic material or even a layer of hydrophobic material other than graphene.

Even in very thin layers, graphene has a great hydrophobic character. The probe of the invention can thus be of small size, the graphene layer being only a few atoms thick.

With reference to FIG. 2, a particular embodiment will now be described. A probe according to the invention is shaped to move here in a blood vessel 10 filled with blood under the action of a field electric. The electric field causes a displacement of the diffuse layer in one direction (as illustrated by the dashed arrows) and thus a displacement in the opposite direction of the probe.

The probe comprises a head 20 and a tail 30 in the form of a substantially circular helix. The tail 30 is relatively flexible and natural oscillations of the tail 30 thus participate in the movement of the probe in the blood vessel, said tail mimicking the natural behavior of a flagellum. Since a method of manufacturing such a probe is well known in the prior art, it will not be described in more detail here.

The entire probe is covered with a layer of hydrophobic material.

Various known methods can be employed to cover the probe with such a layer of material. The method can be chosen depending on the material with which it is desired to form the layer or on the thickness that it is desired to give to said layer. A first deposition process consists of depositing the layer of hydrophobic material 40 on the probe, for example before the creation of the tail 30, by a so-called spin coating (better known in English as "spin coating"). According to one variant, the layer of hydrophobic material 40 is directly adhered to the probe. According to another variant, the hydrophobic material layer 40 is formed by directly synthesizing said layer on the probe before creating the tail 30.

According to the invention, the layer of hydrophobic material 40 is graphene which has many advantages as already mentioned.

In a preferred manner, the graphene layer is only an underlayer of the probe and the probe comprises a layer of biocompatible material 50 which completely covers the head 20 of said probe. Of course, the layer of biocompatible material 50 is chosen not to degrade the graphene layer and in particular its hydrophobic character. Thus, even coated with a layer of biocompatible material 50, the graphene layer continues to facilitate movement of the probe in the blood vessel by reducing frictional forces and amplifying the electroosmosis phenomenon. The layer of biocompatible material 50 further isolates the probe from the blood and in particular to make the probe less toxic to the body in which it moves.

Preferably, the layer of biocompatible material 50 is gold.

The invention is not limited to what has just been described and encompasses any variant within the scope defined by the claims.

In particular, the probe of the invention may perform tasks more complex than a simple displacement. According to a preferred but non-limiting embodiment, the probe comprises means for performing a localized surgical procedure (sampling, injecting a drug, taking images, etc.).

In particular, although here the probe moves in a blood vessel, the probe is shaped to move in a volume filled with fluid as an element of the digestive system. In a preferred manner, the probe is shaped to move in a small volume and has a maximum length of a few tens of micrometers. Preferably, the probe has a length of between 10 and 100 micrometers. Preferably, the probe has a transverse dimension of a few tens of nanometers. Preferably, the probe has a transverse dimension of 20 nanometers.

Although in the embodiment described, the fluid is blood, the probe can be moved in any type of fluid even viscous. Although here the probe is displaced by a phenomenon of electro-osmosis caused by an electric field, the probe can be manipulated otherwise. For example, the probe may include a motor. In addition, the method for moving the probe according to the invention can be implemented for a probe covered at least in part with a layer of hydrophobic material which does not have a substantially circular helical tail. Indeed, the inventors have been able to demonstrate that covering the probe at least in part with a layer of hydrophobic material influences the movement of the probe more than the actual shape of the probe. It will be preferred, however, that the probe of the invention comprises a substantially circular helical tail, said tail facilitating the movement of the probe naturally. Preferably, the tail will have a radius of between 1 micrometer and 5 micrometers.

Moreover, the probe may have any absolutely any shape. The probe may be shaped simply in the shape of a warhead or may be only a substantially circular helical tail (as shown in Figure 3).

Although here the entire probe is covered with a layer of hydrophobic material, the probe may be only partially covered with a layer of hydrophobic material. According to a particular embodiment, if the probe comprises a tail shaped substantially circular helix, at least the tail will be covered with a layer of hydrophobic material.

Two main factors must influence the choice of the hydrophobic material: the amplification of the electroosmosis phenomenon by the hydrophobic material and the thickness of the layer of hydrophobic material necessary for said layer to have a high hydrophobic character. The layer of hydrophobic material may for example be Teflon (trademark).

Although here the layer of biocompatible material covers only part of the probe, the layer of biocompatible material may cover the entire probe. The layer of biocompatible material may be of a different material than gold. For example, the layer of biocompatible material is of polymeric material. The probe may also be covered with a gold layer and a layer of polymer material in addition to the layer of hydrophobic material.

Claims

A conformal probe for moving in a volume filled with fluid, for example a blood vessel (10), the probe being at least partially covered with a layer of hydrophobic material (40) and characterized in that the hydrophobic material is graphene.

2. Probe according to claim 1, furthermore covered at least in part with a layer of biocompatible material (50).

The probe of claim 2, wherein the biocompatible material is gold.

The probe of claim 2, wherein the biocompatible material is a polymeric material.

5. Probe according to claim 1, comprising a substantially circular helical tail (30).

The probe of claim 5, wherein at least the tail (30) of the probe is covered with the layer of hydrophobic material (40).

7. A method for moving a probe according to one of the preceding claims, the method comprising the step of creating in the fluid an electric field under the action of which the probe moves in the volume filled with fluid.

8. Use of the probe according to claims 1 to 6 in a filled volume of fluid having a Reynolds Number less than 0.1.