WO2011012741A2

WO2011012741A2 - Microscopy device with tuning fork and rectilinear tip

Info

Publication number: WO2011012741A2
Application number: PCT/ES2010/000297
Authority: WO
Inventors: Manuel Puig Vidal; Jorge OTERO DÍAZ
Original assignee: Universidad De Barcelona
Priority date: 2009-07-31
Filing date: 2010-07-12
Publication date: 2011-02-03
Also published as: ES2354795B1; ES2354795A1; WO2011012741A3

Abstract

The device has a tuning fork and a rectilinear tip attached to one tine of the fork, a surface for supporting objects to be analysed and means for holding and moving the fork, said means being positioned so that the tip is inclined with respect to the support surface, at an angle that enables exploration with a rectilinear tip without the fork coming into contact with the objects or the liquid in which said object may be submerged, at the same time allowing visual access to the position of the end of the rectilinear tip from above said support surface, and makes it possible to use a plurality of tuning fork/tip assemblies, thereby enabling simultaneous measurement of several physical parameters of the surface of the object.

Description

Microscopy device provided with a resonant fork and a rectilinear tip

The invention relates to an atomic force microscopy (AFM) device equipped with a resonant fork and a tip that allows to explore submerged objects, visually control their movement and obtain high quality factors.

STATE OF THE TECHNIQUE

In a manner already known to those skilled in the art, certain scanning microscopes, mainly near-field scanning microscopes (SNOM), are based on devices provided with at least one resonant fork and a tip fixed to one of its legs.

These devices are provided with means to support the resonant fork by its base and move it to explore objects placed on a support surface that supports the objects to be analyzed, for example tissues, cells, etc.

An example of this technique is described in patent application WO 03019238, which describes a microscope with reconfigurable scanning probe for multi-point scanning with a transparent interface of near-field optical microscopes, in which several tips are used. AFM, preferably fixed to resonant forks.

In WO 03019238 the tips are curved so that they come in contact perpendicularly with the surface to be analyzed and so that it is possible to keep the horizontal resonant fork and sufficiently far from the object to be analyzed, preventing the resonant fork from coming into contact with the surface. . Simultaneously, it allows visually access from above the end of the tip, making it possible to monitor its position and therefore control its movement.

However, these features have the following drawbacks: - The bent tips are much more expensive and fragile than the rectilinear ones, which means higher costs, even prohibitive considering that it is a fungible material necessary in AFM laboratories that must be replaced very frequently.

- The operation of the resonant tip / fork with bent tips is poor because most of it is submerged in the liquid, which provides a low quality factor.

EP 791,802 describes a scanning near field interatomic force microscope similar to that of the Lewis patent and presenting the same drawbacks.

Another example of these techniques is described in US 6,094,971, which describes a scanning probe microscope provided with non-optical means for the detection of normal sample-tip interactions. This device employs an atomic force detection tip disposed attached to a leg of a resonator whose other leg can vibrate freely. As described in the patent and can be seen in the figures, the tip is arranged perpendicular to the surface to be explored, the resonator being perpendicular or parallel to it according to the application. However, it presents the

disadvantages that it does not allow guidance of the tip with the optical microscope nor does it allow cooperation between several tips operating

simultaneously on the same area.

Finally, US 6,515,279 describes a near-field scanning optical microscope provided with a high quality factor piezoelectric sensor element, in which a tip attached to a resonator is also used. However, the resonator operates parallel to the surface whereby the tip should be bent to make measurements that have the same drawbacks as the object of the Lewis patent.

Therefore, despite these proposals, the problem of providing a low-cost device that allows visually accessing the tip for monitoring, which allows cooperation between a plurality of points that operate simultaneously, but that allows to operate remains unresolved. in liquids with a high quality factor, problem that solves the present invention with a simple and effective solution.

Throughout the entire description and the claims the term "comprises" and its derivatives, in any case imply the exclusion of other technical characteristics, additives, components, or stages.

EXPLANATION OF THE INVENTION

The present invention provides a microscopy device provided with at least one resonant fork and a fixed rectilinear tip.

longitudinally to one leg of said resonant fork, a support surface for supporting objects to be analyzed and means for holding and displacing the resonant fork, said means holding the fork by its base so that the other leg of the resonant fork can vibrate freely, characterized in that said means for supporting and displacing the resonant fork are arranged so that said resonant fork and the rectilinear tip are inclined at an angle with respect to said support surface, said angle being such that it allows exploration with a rectilinear tip while preventing the resonant fork from coming into contact with the objects or a liquid where said object is submerged, allowing simultaneously access visually to the position of the end of the rectilinear tip from above said support surface and allowing Ia cooperation between a plurality of operating tips

simultaneously on the same area.

Therefore, these characteristics simultaneously solve the

inconveniences mentioned above, because:

- Allows the use of long, straight tips to access objects to be analyzed immersed in liquids. These tips are inexpensive, do not require any specific form and their fixation to resonant forks in the longitudinal direction is easy.

- Prevents the resonant fork from coming into contact with the liquid containing the sample to be analyzed, allowing at the same time to see the end of the tip from above to control its position and movement, that is, allows to use an optical microscope arranged on the tips.

- Finally, it allows a plurality of resonant fork / tip assemblies to be arranged with the ends of the tips arranged very close to each other, which allows simultaneous cooperation between the tips. By

Simultaneous cooperation should be understood that the tips can measure simultaneously in an area of 100x100 μm ² and, for example, measure the elasticity, impedance or capacity of a cell membrane.

According to preferred embodiments of the invention, the device may comprise the following optional features:

- The tip is inclined with respect to said support surface with an angle between 30 and 60 °, and preferably between 50 and 55 ° in order to place the tip as vertical as possible but still visible.

- The tip protrudes from the end of the leg of the resonant fork a distance between 3.8 and 4.2 mm, preferably 4 mm.

- The resonant fork has a length between 5 and 7 mm.

- The tip is a fiber optic tip, for example to measure Ia

vibration propagation with a view to determining its elasticity constant, or a metal tip, to measure electrical parameters

(impedances, conductances, capacities, etc.).

Finally, the microscopy device of the invention allows the cooperation of a plurality of tips operating simultaneously on the same area. As an example, a particularly useful configuration presented schematically comprises a second resonant fork and a second rectilinear tip similar to the first resonant fork assembly and tip facing it, in which both assemblies are arranged so that the two tips can make measurements on the same area simultaneously and, more preferably, the two points are arranged in the same vertical plane facing each other.

Other objects, advantages and characteristics of the invention will appear for the expert in the field from the reading of the invention and the practical implementation of the invention. The following examples and drawings are offered by way of illustration and are not intended to limit the scope of the present invention. In addition, the present invention covers all possible combinations described below.

BRIEF DESCRIPTION OF THE DRAWINGS

Fig. 1 shows a schematic drawing of the essential elements of the device of the invention.

Fig. 2 shows a schematic drawing of a preferred embodiment of the invention comprising two resonant fork / tip assemblies arranged under an optical microscope.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

As shown in Fig. 1, the invention relates to a type of microscopy device 1 known, already described, for example in US 6,094,971, provided with a resonant fork 3 and a rectilinear tip 2 fixed longitudinally to a of its legs 3a, a support surface 4 for supporting objects 5 to be analyzed and means for supporting and displacing the resonant fork 3.

In general, the means support the fork by its base 3c, that is, the opposite end to that on which the tip is fixed, so that the other leg 3b of the resonant fork 3 can vibrate freely.

Specifically, the microscopy device of the invention is characterized in that the means for holding and displacing the resonant fork 3 are arranged so that the rectilinear tip 2 is inclined an angle α with respect to the support surface 4.

This angle is such that it allows to explore with a rectilinear tip 2 while avoiding that the resonant fork 3 comes into contact with the objects 5, or a liquid 6 in which they are immersed, allowing simultaneously, to visually access the position of the end 2a of the rectilinear tip 2 from above the support surface 4.

According to a preferred embodiment of the invention, the tip 2 is inclined with respect to the support surface 4 with an angle α between 30 and 60 °, and preferably between 50 and 55 °, the tip 2 protrudes from the end of the leg of The resonant fork 3a a distance I between 3.8 and 4.2 mm, preferably 4 mm, and the resonant fork 3 has a length L between 5 and 7 mm. It has been proven that these dimensions provide good quality factors in the exploration of objects immersed in liquids. For example, to explore objects 5 submerged in a 2 mm layer of water, with a tip protruding 4 mm from the resonant fork, a minimum angle of 30-40 ° is sufficient.

According to the parameters to be measured, the tip 2 is a fiber optic tip or a metal tip.

As shown in Fig. 2, in which a second embodiment of the invention is shown, the microscopy device 1 comprises a second resonant fork 3 'and a second rectilinear tip 2' similar to the other set of resonant fork and tip 2, 3 and arranged in front of the latter, in which both assemblies are arranged so that both tips 2, 2 'can carry out measurements on the same area

simultaneously. Obviously, the characteristics of the invention allow a plurality of resonant fork / tip assemblies to be arranged, which in turn allows several physical parameters of the object surface to be measured simultaneously. If more points were to be arranged, the resonant forks could be arranged with both legs inscribed in a plane perpendicular to the surface.

As can be seen in Fig. 2, the microscopy device of the invention allows an optical microscope 7 to be placed on the sample with its axis 7a substantially perpendicular to said support surface 4, to control the movement of the tips on the surface to explore The dimensions described above allow the use of an optical microscope (x50) with a focal length F of approximately 8 mm. In this case, with a tip protruding 4 mm from the resonant fork, an angle of 50-55 ° is available to avoid the collision with the objective of the microscope.

Claims

1. Microscopy device (1) provided with at least one resonant fork (3) and a rectilinear tip (2) fixed longitudinally to a leg (3a) of said resonant fork (3), a support surface (4) to support objects (5) to be analyzed and means for supporting and displacing the resonant fork (3), holding said means to the fork by its base (3c) so that the other leg (3b) of the resonant fork (3) can vibrate freely, characterized in that said means for supporting and displacing the resonant fork (3) are arranged so that said rectilinear tip (2) is inclined an angle (α) with respect to said support surface (4), said angle being such which allows to explore with a rectilinear tip (2) while avoiding that the resonant fork (3) comes into contact with the objects (5) or a liquid (6) where said object is submerged, simultaneously making it possible to visually access the end position (2a) of The rectilinear tip (2) from above said support surface (4) and which allows to place a plurality of resonant fork / tip assemblies, which in turn allows to measure several physical parameters of the surface of the object simultaneously.

2. Device according to claim 1, wherein said tip (2) is inclined with respect to said support surface (4) with an angle (α) between 30 and 60 °, preferably between 50 and 55 °.

3. Device according to any of the preceding claims, wherein said tip (2) protrudes from the end of the leg of the resonant fork (3a) a distance (I) between 3.8 and 4.2 mm, preferably 4 mm .

Device according to any one of the preceding claims, wherein said resonant fork (3) has a length (L) between 5 and 7 mm.

5. Device according to claim 1, wherein said tip (2) is a fiber optic tip or a metal tip.

6. Device according to any of the preceding claims, which it comprises a second resonant fork (3 ') and a second rectilinear tip (2') similar to the other set of resonant fork and tip (2, 3) and arranged opposite it, in which both assemblies are arranged so that both tips (2, 2 ') can simultaneously perform measurements on the same sample area.

7. Device according to the preceding claim, in which the two tips (2, 2 ') are arranged in the same vertical plane facing each other.