Micro-gripper

Abstract

A micro-gripper (1) is provided comprising a support (2) defining a longitudinal axis (2a) and developing at least transversely to the longitudinal axis (2a); a linear piezoelectric actuator (3) connected to the support (2), developing along the longitudinal axis (2a) and configured to deform along the longitudinal axis (2a) in response to external electrical impulses; a driving head (4) integral with the actuator (3) at a side of the actuator (3) opposite to the support (2) such that the head (4) defines different positions along the longitudinal axis (2a) proportional to deformations of the actuator (3); a pair of arms (5) connected to the support (2), mutually specular with respect to the longitudinal axis (2a), alongside the actuator (3) and the head (4), so as to define an opening direction (5a) perpendicular to the longitudinal axis (2a) and each comprising a lever (50) developing transversely to the longitudinal axis (2a), defining a first end (50a) proximal to the actuator (3) and a second end (50b), and constrained to the support (2) by means of a fulcrum (6) placed between the ends (50a, 50b) and defining a rotation axis (6a), and a bar (51) developing transversely to the lever (50) from the second end (50b) and comprising at least one jaw (51a); wherein each said lever (50) is constrained to the head (4) from its respective first end (50a) exclusively by means of an elastically yielding main connecting rod (7) so that a movement of the head (4) along the longitudinal axis (2a) is directly transmitted to the first end (50a) and the lever (50) directly transmits the movement to the bar (51).

Description

[0001] DESCRIPTION

[0002] MICRO-GRIPPER

[0003] The present invention relates to a micro-gripper of the type specified in the preamble of the first claim.

[0004] In particular, the present invention relates to a miniaturised gripping member suitable for enabling the gripping of small-sized objects, such as for example microelectronic components, by piezoelectric actuation.

[0005] As is known, in the present historical period there is growing interest in miniaturisation, for example in the field of microelectronics, in particular the manufacture of mobile phones, biomedical devices and especially fibre optic sensors. The field of fibre optic sensors is, in fact, in continuous development due to the advantages that this new type of sensors offers compared with conventional ones.

[0006] The assembly of small-sized components in the above-mentioned fields requires the use of increasingly miniaturised gripping members, in particular the use of micro-grippers whose operation is regulated by piezoelectric-type means.

[0007] Among all products, piezoelectric micro-grippers are the most suitable for the precise handling of small components.

[0008] The micro-grippers of the known art generally define mostly two types of deformation mechanisms.

[0009] A first deformation mechanism is, for example, described in patent application CN-A-1110788834.

[0010] The latter describes a gripper, shown in Fig. 5, with non-parallel opening, which couples piezoelectric elements to a deformation mechanism configured to amplify the movement of the piezoelectric element and contains a pair of jaws, i. e. , the means of the gripper suitable for gripping objects.

[0011] The mechanism is defined as a parallelogram mechanism in which the elongation of a central piezoelectric strip determines the inclination of four connecting rods placed at the sides of the strip so as to control a proportional rotation of the corresponding arm of a jaw.

[0012] A second deformation mechanism is, instead, described in patent application CN- A-105619377.

[0013] The latter describes a gripper, shown in Fig. 7, with non-parallel opening, which, similarly to the previous gripper, couples piezoelectric elements to a deformation mechanism configured to amplify the movement of the piezoelectric actuator and contains the jaws, i.e. , the means of the gripper suitable for gripping objects.

[0014] However, the mechanism is, in this case, defined as a lever mechanism in which essentially the piezoelectric element pushes the arm relating to a jaw along a direction so as to impose on the arm a rotation around a fulcrum.

[0015] The lever and parallelogram mechanisms just described summarise almost all the solutions adopted in piezoelectric micro-grippers, as well as almost all of the so-called compliant mechanisms for amplifying piezoelectric actuators in any field.

[0016] Despite widespread use, the known art described includes some significant drawbacks.

[0017] In particular, in the parallelogram mechanism, when one tries to obtain a high transmission ratio, i.e., attempts are made to increase the amplification of the displacement of the piezoelectric component by reducing the value of the inclination angle of the connecting rods, the latter are subjected to a high reaction force, tending towards infinity for very small angles, and therefore, their elongation compromises the correct functioning of the mechanism.

[0018] Moreover, when a parallelogram mechanism is used, there are normally at least four yielding elements, acting as fulcrums, between the arms and the mechanism. Evidently, the higher the number of deformable elements, the greater the force subtracted from the piezoelectric component and, therefore, the less it deforms and the mechanism may result in smaller displacement, and consequently a smaller opening.

[0019] If, in an attempt to improve the behaviour of the deformable elements, a configuration with more slender redundant elements is preferred, the mechanisms of the known art are prone to easy breakage and a greater structural complexity.

[0020] With regard to lever mechanisms, instead, it must first be considered that, in order for the lever effect to work, the arms must necessarily be sized within predetermined limits. This, of course, does not allow, for example, to slim down some parts by reducing the dimensions of the parts of the gripper.

[0021] In fact, the lateral bulk of grippers with a lever mechanism is generally greater than that of grippers with a parallelogram mechanism.

[0022] It should also be added that the deformable elements in lever mechanisms are also comparable in number to those in parallelogram mechanisms and can easily reach even ten in number.

[0023] This implies greater structural complexity and lower resistance of the gripper with a lever mechanism even compared to the gripper with a parallelogram mechanism.

[0024] Considering all mechanisms in general, moreover, when one intends to make grippers with parallel opening, it is necessary to introduce redundant elements, for example overlapping pairs of arms, so as to limit the rotation of the jaws around the rotation axis of the arms and guide their movement in parallel.

[0025] In addition to what has already been described, it should also be noted that, when it is necessary to preload the piezoelectric actuator inserted in a deformation mechanism to adjust the opening of the jaws, screws are used, as for example described in CN-A-1110788834, which when applied may permanently alter the mutual distance of the jaws, different from the design distance, introducing a significant factor of indeterminacy concerning the size of the object that can be manipulated with the micro-gripper.

[0026] In conclusion, another limitation of the screws, or set screws, for adjustment is that, by resting directly on the piezoelectric actuator, they constitute an inadequate base and, when means are interposed to adapt the irregularity of the screw or set screw to the necessary regularity required by a support base for a piezoelectric actuator, the mechanism becomes more expensive and complex than others.

[0027] In this situation, the technical task underlying the present invention is to devise a micro-gripper capable of substantially overcoming at least part of the above- mentioned drawbacks.

[0028] Within said technical task, an important object of the invention is to obtain a micro-gripper that allows to ensure a good amplification ratio with high structural simplicity.

[0029] Another important object of the invention is to make a micro-gripper not prone to breakage and, therefore, long-lasting so as to maintain suitable rigidity to enable firm gripping of objects.

[0030] Furthermore, a further object of the invention is to make a micro-gripper that allows, in at least one embodiment, a parallel opening of the jaws so as to further increase the gripping capacity.

[0031] Therefore, a further object of the invention is to make a micro-gripper that is easily adjustable, i.e., allows for the adjustment of the opening of the jaws without introducing modifications that lead to problems of indeterminacy in the characteristic dimensions compared with those of the design.

[0032] The technical task and the specified objects are achieved by a micro-gripper as claimed in the annexed claim 1 .

[0033] Preferred technical solutions are highlighted in the dependent claims.

[0034] The characteristics and advantages of the invention are clarified below by the detailed description of preferred embodiments of the invention, with reference to the accompanying drawings, in which:

[0035] Fig. 1 shows a longitudinal view of a micro-gripper according to the invention in a first embodiment;

[0036] Fig. 2a illustrates a longitudinal view of a micro-gripper according to the invention in a second embodiment in which an adjusting element is present for modifying the opening of the jaws;

[0037] Fig. 2b is a longitudinal view of the micro-gripper of Fig. 2a in which the position of the adjusting element has been modified and the opening of the jaws has been reduced;

[0038] Fig. 3 represents a longitudinal view of a micro-gripper according to the invention in a third embodiment in which interchangeable jaws are present;

[0039] Fig. 4a shows a graph, in which the abscissa represents the activation steps and the ordinate the elongation in pm, relating to the behaviour of the mechanism of a micro-gripper according to the invention evaluated by FEM analysis, in which the stiffness of the mechanism is highlighted, in this case equal to 2 N / mm, and the elongation of the free piezoelectric actuator, shown by the upper line with a maximum of 23.76 pm, and when inserted in the mechanism, shown by the lower line with a maximum of 17.68 pm and maximum force developed equal to 244.06 N;

[0040] Fig. 4b illustrates a graph, in which the abscissa represents the activation steps and the ordinate the opening in mm, relating to the behaviour of the mechanism of a micro-gripper according to the invention evaluated by FEM analysis, in which the maximum amplitude of the mechanism is highlighted, given by the maximum of the upper line equal to 1.2 mm, which, compared with the elongation of the piezoelectric actuator, allows determining an amplification factor equal to 65.11 and a bending stiffness, evaluated considering the imposed rotation defined by the lower line, in this case equal to 2.07 N / mm;

[0041] Fig. 5 is a perspective view of a micro-gripper of the known art comprising a double parallelogram mechanism;

[0042] Fig. 6a represents a graph, in which the abscissa represents the activation steps and the ordinate the elongation in pm, relating to the behaviour of the parallelogram mechanism of a micro-gripper of the known art evaluated by FEM analysis, in which the stiffness of the mechanism is highlighted, in this case equal to 2 N / mm, and the elongation of the free piezoelectric actuator, shown by the upper line with a maximum of 23.76 pm, and when inserted in the mechanism, shown by the lower line with a maximum of 17.98 pm and maximum force developed equal to 232.04 N;

[0043] Fig. 6b shows a graph, in which the abscissa represents the activation steps and the ordinate the opening in mm, relating to the behaviour of the parallelogram mechanism of a micro-gripper of the known art evaluated by FEM analysis, in which the maximum amplitude of the mechanism is highlighted, given by the maximum of the upper line equal to 0.92 mm, which, compared with the elongation of the piezoelectric actuator, allows determining an amplification factor equal to 51 .02 and a bending stiffness, evaluated considering the imposed rotation defined by the lower line, in this case equal to 2.07 N / mm; and

[0044] Fig. 7 illustrates a perspective view of a micro-gripper of the known art comprising a lever mechanism.

[0045] In the present document, the measurements, values, shapes and geometric references (such as perpendicularity and parallelism), when associated with words like "approximately" or other similar terms such as "almost" or "substantially", are to be understood as subject to measurement errors or inaccuracies due to production and / or manufacturing errors and, above all, to a slight deviation from the value, measurement, shape or geometric reference with which they are associated. For example, such terms, if associated with a value, preferably indicate a deviation not exceeding 10% of the value itself.

[0046] Furthermore, when used, terms such as “first”, “second”, “upper”, “lower”, “main” and “secondary” do not necessarily identify an order, priority of relation or relative position, but may simply be used to more clearly distinguish different components from one another.

[0047] Unless otherwise specified, as appears from the following discussions, terms such as “processing”, “computing”, “determination”, “calculation”, or similar are considered to refer to the actions and / or processes of a computer or similar electronic computing device that manipulates and / or transforms data represented as physical quantities, such as electronic signals within registers of a computing system and / or memories into other data similarly represented as physical quantities within computing systems, registers or other information storage, transmission or display devices.

[0048] The measurements and data reported herein are to be considered, unless otherwise indicated, as taken in International Standard Atmosphere ICAO (ISO 2533:1975).

[0049] With reference to the Figures, the micro-gripper according to the invention is globally denoted by the number 1.

[0050] The micro-gripper 1 is a tool useful for handling microscopic objects, i.e. , in the field of miniaturisation, such as microelectronics, the manufacture of mobile phones, biomedical devices and especially fibre optic sensors.

[0051] The micro-gripper 1 thus has an extremely reduced structure that is not comparable to conventional grippers.

[0052] The micro-gripper 1 comprises at least one support 2.

[0053] The support 2 is the static portion of the micro-gripper 1 , i.e., the portion that holds the various components of the micro-gripper 1 .

[0054] In particular, the support 2 defines at least one longitudinal axis 2a. The longitudinal axis 2a is the axis along which the micro-gripper 1 develops. Moreover, the longitudinal axis 2a is substantially transverse to the opening and, therefore, it is the axis with respect to which the micro-gripper 1 can overall expand or contract to grip an external object.

[0055] The support 2 also develops at least transversely to the longitudinal axis 2a. Therefore, the support 2 may be made, for example, from a plate or strip developing transversely to the longitudinal axis 2a, for example perpendicularly.

[0056] The micro-gripper 1 thus also comprises an actuator 3. The actuator 3 is substantially the portion of the micro-gripper 1 configured to operate it to produce an expansion or contraction to release or engage an object. The actuator 3 is of linear type. Moreover, as in most micro-grippers, the actuator 3 is of piezoelectric type. This means that the actuator 3 is configured to deform, producing elongations or contractions, in response to external electrical impulses.

[0057] In detail, preferably, the actuator 3 develops along the longitudinal axis 2a. Furthermore, the actuator 3 is configured to deform along the longitudinal axis 2a. Therefore, the actuator 3 is connected to the support 2. Preferably, the actuator 3 is at least partially integral with the support 2 so that it can expand relative thereto. The micro-gripper 1 thus also comprises a driving head 4.

[0058] The head 4 may be distinct from or integrated with the actuator 3. In fact, the head 4 may be an end portion of the actuator 3.

[0059] More generally, the head 4 is at least integral with the actuator 3 at a side of the actuator 3 opposite to the support 2. Therefore, the head 4 is configured, with respect to the actuator 3, so as to define different positions relative to the support 2 along the longitudinal axis 2a. The positions reached by the head 4 with respect to the support 2 are, naturally, proportional to the deformations of the actuator 3.

[0060] In detail, preferably, contractions of the actuator 3 result in an approach of the head 4 to the support 2, whereas elongations of the actuator 3 result in a movement of the head 4 away from the support 2.

[0061] The micro-gripper 1 thus also comprises a pair of arms 5.

[0062] The arms 5 are the elements that determine the gripping of the external object. Therefore, they define the movable part, relative to the support 2, of the microgripper 1 suitable for interacting with the external object.

[0063] The arms 5 are thus connected to the support 2. In particular, the arms 5 are preferably connected to the support 2 in a configuration that is mutually mirrored with respect to the longitudinal axis 2a. In particular, the arms 5 are preferably placed alongside the actuator 3 and the head 4.

[0064] Therefore, the arms 5 form the opening of the micro-gripper 1 and, in fact, define an opening direction 5a. The opening direction 5a is preferably perpendicular to the longitudinal axis 2a. Therefore, the opening direction 5a is precisely the direction along which the micro-gripper 1 defines its own opening.

[0065] Preferably, each of the arms 5 comprises at least one lever 50 and one bar 51.

[0066] The lever 50 develops transversely to the longitudinal axis 2a. In at least one configuration of the micro-gripper 1 , as described more fully below, the lever 50 develops perpendicularly to the longitudinal axis 2a.

[0067] Furthermore, the lever 50 defines a first end 50a. The first end 50a is proximal to the actuator 3. Therefore, the first end 50a is the portion of the lever 50 closest to the actuator 3.

[0068] Moreover, the lever 50 also defines a second end 50b.

[0069] The second end 50b is preferably opposite to the first end 50a.

[0070] Therefore, the second end 50b is substantially the portion of the lever 50 farthest from the actuator 3, that is, from the longitudinal axis 2a.

[0071] Thus, the lever 50 is constrained to the support 2. In particular, preferably, the lever 50 is constrained to the support 2 by means of a fulcrum 6.

[0072] The fulcrum 6 is placed between the ends 50a, 50b. The fulcrum 6 may be made by a mechanical hinge, for example a device equipped with two mutually rotating movable portions, or by a bearingless device, for example a beam element configured to flex to allow relative rotations between the lever and the support 2.

[0073] In general, the fulcrum 6 defines a rotation axis 6a. The rotation axis 6a is preferably perpendicular to a plane defined between the main axis 2a and the opening direction 5a. Moreover, each arm 5 preferably comprises a bar 51. The bar 51 is an elongated element, for example a beam. Furthermore, the bar 51 preferably develops transversely to the lever 50. The bar 51 is thus integral with the lever 50. In this regard, the bar 51 may be constrained to the lever 50 or, more appropriately, made in one piece therewith.

[0074] Even more in detail, the bar 51 develops transversely to the lever 50 starting from the second end 50b. This means that a movement around the rotation axis 6a through the fulcrum 6 of the lever 50 also results in a corresponding movement of the bar 51 around the rotation axis 6a.

[0075] The micro-gripper 1 also comprises further features.

[0076] Indeed, advantageously, each lever 50 is constrained to the head 4. In particular, each lever 50 is constrained to the head 4 from its respective first end 50a.

[0077] Furthermore, the lever 50 and the head 4 are constrained exclusively by means of a main connecting rod 7. The main connecting rod 7 is an elongated element that enables the connection of the first end 50a and the head 4. In particular, the main connecting rod 7 is elastically yielding. The yielding capacity of the main connecting rod 7 may be achieved in one or more ways. For example, the main connecting rod 7 may flex to allow relative movement between the lever 50 and the head, or, more appropriately, the main connecting rod 7 may be configured not to flex but to move, relative to the head and / or lever 50, at its own ends while maintaining the direction of its own axis unchanged. In general, the main connecting rod 7 is configured to transmit the translational motion imposed on the head 4 by the actuator 3 and, at the same time, to allow relative movements, such as rotations, between the lever 50 and the head 4 in a controlled manner.

[0078] Advantageously, a movement of the head 4, which is determined by the passage between positions along the longitudinal axis 2a, is therefore directly transmitted to the first end 50a of the lever 50. In turn, the lever 50 behaves as a first-degree lever and transmits the movement directly to the bar 51 by rotating about the rotation axis 6a.

[0079] Therefore, in general, the support 2, the actuator 3, the head 4 and the arms 5 together form a hybrid mechanism, partly similar to a parallelogram mechanism and partly to a lever mechanism. However, advantageously, the mechanism of the micro-gripper 1 defines a single transmission stage of the movement imposed by the actuator 3.

[0080] Preferably, among the various configurations that may be achieved by the actuator 3, the latter preferably defines at least one rest configuration. The rest configuration is substantially an initial or reference zero configuration. In fact, the rest configuration is realised in the absence of external stresses. In the rest configuration, preferably, each of the main connecting rods 7 lies parallel to the longitudinal axis 2a. Furthermore, preferably, the lever 50 lies perpendicular to the main axis 2a.

[0081] In addition, the mechanism may also define further specific geometric characteristics identifiable in the rest configuration.

[0082] For example, in the rest configuration, the bar 51 is perpendicular to the lever 50 such that, when the actuator 3 is in the rest configuration, the bar 51 is parallel to the main axis 2a.

[0083] In any case, preferably, the bar 51 comprises at least one jaw 51a.

[0084] The jaw 51a is substantially suitable for contacting an object to determine its grip. Therefore, the jaw 51 a defines at least one contact zone with said object, which in turn defines a surface chosen among smooth, knurled, and shaped.

[0085] The bar 51 may be a one-piece element in which the jaw 51 a may be formed from a free end zone of the bar 51 .

[0086] Alternatively, one or more of the arms 5 may be configured as follows.

[0087] In a further preferred embodiment, as shown in Figs. 2a-2b, in one or more of the arms 5, the bar 51 comprises a body 51b in addition to the jaw 51 a.

[0088] The body 51 b is preferably connected to the lever 50. Therefore, the jaw 51 a is distinct and separate from the body 51 b. In addition, advantageously, the jaw 51a is constrained to the body 51 b by means of a pair of secondary connecting rods 52. The secondary connecting rods 52 are similar to the main connecting rod 7. Therefore, the secondary connecting rods 52 are also configured to allow mutual movement between the body 51 b and the jaw 51a in a controlled manner. They are, in fact, elastically yielding; furthermore, in detail, the secondary connecting rods 52 are configured to form an articulated parallelogram, being mutually parallel, such that the jaw 51a may roto-translate with respect to the body 51 b while maintaining its orientation with respect to the longitudinal axis 2a and / or the opening direction 5a.

[0089] Therefore, the jaw 51 a, by virtue of the movement allowed by the secondary connecting rods 52 with respect to the body 51 b, may define at least one translation along the opening direction 5a with respect to the body 51 b.

[0090] Therefore, one or more of the arms 5 also preferably comprises an adjusting device 53

[0091] The adjusting device 53 is integral with the body 51 b. Furthermore, advantageously, the adjusting device 53 is configured to exert a thrust on the jaw 51 a transversely to the longitudinal axis 2a, with respect to the body 51 b, in order to achieve the translation along the opening direction 5a.

[0092] This therefore makes it possible to adjust the overall opening of the micro-gripper 1 independently of the movement of the actuator 3, i.e., independently of the movement of the head 4.

[0093] The adjusting device 53, in more detail, may comprise a base 53a and an adjusting element 53b.

[0094] The base 53a is preferably integral with the body 51 b. The adjusting element 53b is, instead, movable transversely to the longitudinal axis 2a with respect to the base 53a.

[0095] Therefore, the adjusting element 53b is preferably movable in proportion to a relative rotation between the adjusting element 53b and the base 53a.

[0096] For example, the adjusting element 53b may comprise, or be constituted by, a screw defining a first peripheral thread. Therefore, the base 53a may comprise a hole defining a second thread compatible with the first thread so as to operatively and compatibly accommodate the screw.

[0097] This means that the adjusting device 53 does not interfere in any way with the actuator 3.

[0098] In particular, furthermore, considering the actuator 3 in the rest configuration, the adjusting device 53 preferably exerts the thrust on the jaw 51a parallel to the opening direction 5a. Therefore, the jaw 51 a preferably develops perpendicularly to the opening direction 5a when the actuator 3 is in the rest configuration, independently of the thrust, i.e., of its position with respect to the body 51 b. This means that the configuration of the adjusting device 53 and of the secondary connecting rods 52 makes it possible to always keep the jaw 51a parallel to the longitudinal axis 2a, when the actuator 3 is in the rest configuration, independently of the position assumed by the jaw 51a transversely to the longitudinal axis 2a, i.e. , independently of the opening imposed on the micro-gripper 1 .

[0099] In a further preferred embodiment, as shown in Fig. 3, in one or more arms 5, the jaw 51 a may comprise a first portion 510 and a second portion 511.

[0100] The first portion 510 is preferably constrained to the body 51 b by the secondary connecting rods 52.

[0101] Moreover, the second portion 511 is removably constrained to the first portion 510 so that it can be replaced. If the second portion 511 is present, it preferably defines the contact zone with the external object.

[0102] Furthermore, the constraint between the portions 510, 511 may be made by mechanical means, such as screws or the like, widely known in the current state of the art.

[0103] It should be noted that the presence or absence of the portions 510, 511 is independent of the presence of the adjusting device 53. In fact, one or more of the bars 51 may comprise a first portion 510 and a second portion 511 in the absence of the secondary connecting rods 52. In this case, for example, the first portion 510 may be integral with the lever 50, in particular made in one piece with it, while the second portion 511 may be removably constrained to the first portion 510.

[0104] In general, the fact that the second portion 511 is replaceable also allows for the realisation of a handling kit.

[0105] The invention therefore also comprises a kit for handling a microscopic object.

[0106] The kit comprises at least one micro-gripper 1 as previously described. Furthermore, preferably, the kit also comprises a jaw 51 a which, in one or more arms 5, comprises a first portion 510 and a plurality of second portions 511 .

[0107] Each of the second portions 511 is, as described, suitably removably constrainable to the first portion 510. Furthermore, advantageously, the second portions 511 define respective contact zones with the object which are mutually different so that the second portions 511 are interchangeable and the micro-gripper 1 may be adapted to different objects.

[0108] The operation of the micro-gripper 1 previously described in structural terms is similar to that of conventional micro-grippers.

[0109] However, the micro-gripper 1 according to the invention achieves significant advantages.

[0110] As is evident from the comparison of Figs. 4a-4b with Figs. 6a-6b, the micro-gripper 1 defines, with substantially equal elongation of the actuator 3, actuation force, and mechanism stiffness, compared to a parallelogram mechanism of the known art, achieving an amplification factor that is significantly grater, in particular approximately 27% greater.

[0111] Therefore, clearly, the micro-gripper 1 makes it possible to ensure a good amplification ratio with high structural simplicity.

[0112] The fact of including few yielding elements, mainly consisting of main connecting rods 7 and fulcrums 6, makes the micro-gripper 1 less prone to breakage and therefore long-lasting, so as to maintain suitable rigidity allowing firm and efficient gripping of objects over time.

[0113] Therefore, the micro-gripper 1 makes it possible to ensure, in at least one embodiment, an almost parallel opening of the jaws 51 a so as to further increase the gripping capacity.

[0114] The adjusting device 53, which does not interfere with the actuator 3, ultimately makes the micro-gripper 1 easily adjustable in its opening without introducing modifications that could lead to problems of indeterminacy in the characteristic dimensions compared to the design ones.

[0115] The invention is susceptible to variants falling within the scope of the inventive concept defined by the claims.

[0116] For example, the lever 50 preferably defines the same distance between each end 50a, 50b and the fulcrum 6. However, these distances could be varied to change the transmission ratio of the movement from the head 4 to each bar 51 .

[0117] In this context, all parts may be replaced by equivalent elements and the materials, shapes and dimensions may be any.

Claims

CLAIMS1. Micro-gripper (1 ) comprising:- a support (2) defining a longitudinal axis (2a) and developing at least transversely to said longitudinal axis (2a);- a linear piezoelectric actuator (3) connected to said support (2) developing along said longitudinal axis (2a) and configured to deform along said longitudinal axis (2a) in response to external electrical impulses;- a driving head (4) integral to said actuator (3) at a side of said actuator (3) opposite to said support (2) such that said head (4) defines different positions relative to said support (2) along said longitudinal axis (2a) proportional to deformations of said actuator (3);- a pair of arms (5) connected to said support (2) mirroring each other with respect to said longitudinal axis (2a), alongside said actuator (3) and said head (4), so as to define an opening direction (5a) perpendicular to said longitudinal axis (2a) along which said micro-gripper (1 ) defines its own opening and comprising each:- a lever (50) developing transversely to said longitudinal axis (2a), defining a first end (50a) proximal to said actuator (3) and a second end (50b) opposite to said first end (50b) and constrained to said support (2) by means of a fulcrum (6) placed between said ends (50a, 50b) and defining a rotation axis (6a) perpendicular to a plane defined between said main axis (2a) and said opening direction (5a), and- a bar (51 ) developing transversely to said lever (50) integral with said lever (50) from said second end (50b) and comprising at least one jaw (51 a) suitable for contacting an object to determine its grip; and characterised in that- each said lever (50) is constrained to said head (4) from said relative first end (50a) exclusively by means of an elastically yielding main connecting rod (7) so that a movement of said head (4), determined by passing between said positions along said longitudinal axis (2a) is directly transmitted to said first end (50a) of said lever (50) and that, in turn, said lever (50) behaves as a lever of the first degree and transmits said movement directly to said rod (51 ) by rotating about said rotation axis (6a).

2. Micro-gripper (1 ) according to claim 1 , wherein in one or more of said arms (5) said rod (51 ) comprises a body (51 b) connected to said lever (50) and said jaw (51 a) is distinct, separated from said body (51 b) and constrained to said body (51 b) by a pair of elastically yielding secondary connecting rods (52) configured to form an articulated parallelogram such that said jaw (51a) can roto-translate with respect to the body (51 b) while maintaining its orientation with respect to said longitudinal axis (2a) and defining at least one translation along said opening direction (5a) with respect to said body (51 b); one or more of said arms (5) further comprising an adjusting device (53) integral with said body (51 b) and configured to exert a thrust on said jaw (51 a) transversely to said longitudinal axis (2a), with respect to said body (51 b), to accomplish said translation along said opening direction (5a) so as to enable said opening to be adjusted independently of said movement of said head (4).

3. Micro-gripper (1 ) according to the preceding claim, wherein said adjusting device (53) comprises at least a base (53a) integral with said body (51 b) and an adjusting element (53b) movable with respect to said base (53a) transversely to said longitudinal axis (2a) in proportion to a relative rotation between said adjusting element (53b) and said base (53a).

4. Micro-gripper (1 ) according to the preceding claim, wherein said adjusting element (53b) is a screw defining a first perimeter thread and said base (53a) includes a hole defining a second thread compatible with said first thread so that said screw can be operatively accommodated.

5. Micro-gripper (1 ) according to any one of the preceding claims, wherein in one or more of said arms (5) said jaw (51 a) comprises a first portion (510) constrained to said body (51 b) by said secondary connecting rods (52) and a second portion (511 ) detachably joined to said first portion (510) in such a manner that it can be replaced.

6. Micro-gripper (1 ) according to the preceding claim, wherein said second portion (511 ) defines a contact zone with said object defining a surface of choice between smooth, knurled and shaped.

7. Micro-gripper (1 ) according to any of the preceding claims, wherein said actuator (3) defines at least one rest configuration in which, in the absence of external stresses, each of said main connecting rods (7) lies parallel to said longitudinal axis (2a) and said lever (50) lies perpendicular to said main axis (2a).

8. Micro-gripper (1 ) according to at least the preceding claim, wherein each said rod (51 ) is perpendicular to said lever (50) such that when said actuator (3) is in said rest configuration, said rod (51 ) is parallel to said main axis (2a).

9. Micro-gripper (1 ) according to at least claims 2 and 8, wherein adjusting device (53) exerts, when said actuator (3) is in said rest configuration, said thrust on said jaw (51 a) parallel to said opening direction (5a); said jaw (51a) developing perpendicular to said opening direction (5a), when said actuator (3) is in said rest configuration, independently of said thrust, i.e. , of its own position with respect to said body (51 b).

10. A kit for manipulating a microscopic object comprising at least one microgripper (1 ) according to any of the preceding claims, wherein in one or more of said arms (5) said jaw (51 a) comprises a first portion (510), a plurality of second portions (511 ) each detachably joined to said first portion (510) so as to be replaceable, defining respective mutually different contact zones with said object so that said second portions (511 ) are interchangeable and said micro-gripper (1 ) can be adapted to different said objects.

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