EP4288499A1

EP4288499A1 - Microstructured dry adhesive for esd-safe handling

Info

Publication number: EP4288499A1
Application number: EP22707014.1A
Authority: EP
Inventors: Patrick MARSHALL; Abdias TELLEZ; Elijah PASCUAL
Original assignee: OnRobot AS
Current assignee: OnRobot AS
Priority date: 2021-02-03
Filing date: 2022-02-02
Publication date: 2023-12-13
Also published as: WO2022167499A1

Abstract

Provided are systems for comprising dry adhesive microstructures for electrostatic discharge (BSD) safe handling of BSD sensitive material. A conductive terminal film may be adjacent to the tips of of the microstructures to interface with the contact surface. In some aspects, a change in material composition of the microstructures in a dry adhesive may affect mechanical and electical properties to enhance or diminish overall adhesive performance and electical discharge performance.

Description

MICROSTRUCTURED DRY ADHESIVE FOR ESD-SAFE HANDLING

BACKGROUND

Artificial fibrillar microstructures have been shown to mimic the dry adhesive capabilities of micro-scale setae on the toes of the gecko lizard. In particular, individual fibrillar microstructures can be configured to conform to an adhering surface to improve real contact area and thereby increase attractive forces (e.g., intermolecular van der Waals forces) between the individual fibers and the contact surface. Dry adhesives, which are not dependent on liquid secretion, can adhere to and release from contact surfaces without leaving residue on the surfaces and with minimal contamination, allowing for repeated uses and longer lifetimes.

Physical characteristics and material properties of fibrillar microstructures can enhance or diminish their adhesive performance. For instance, synthetic fibrillar microstructures may be fabricated or post-treated to comprise tips having specific shapes, such as mushroom-like flaps, that can increase the real contact area between the individual fibers and the contact surface and significantly enhance the dry adhesive performance of these synthetic fibrillar microstructures. In another instance, the synthetic fibrillar microstructures may be fabricated or post-treated to comprise materials having different material properties. In some instances, different material properties, such as material conductivity, may allow for sensing systems to be integrated into the microstructures.

SUMMARY

In an aspect, there is provided an electrostatic discharge (ESD) safe adhesion system, comprising a substrate comprising a surface, wherein the surface comprises a plurality of microstructures. The plurality of microstructures may be configured to interface a target surface, such as to help the ESD-safe adhesion system grip or adhere to the target surface. One or more components of the ESD-safe adhesion system may be subject to, or be a part of, the transfer of electric charge.

Described herein is an ESD-safe dry adhesive system. ESD-safe dry adhesive system disclosed herein can comprise a substrate comprising a surface having a pluarility of microstructures, wherein the substrate and the plurality of microstructures comprises a conductive additive and the dry adhesive system can further comprise a terminal film adjacent to the plurality of microsctructures, wherein a surface of the terminal film is configured to interface a target surface, wherein the terminal film comprises the conductive additive or an additional conductive additive, and wherein the dry adhesive system comprises a ground circuit path from the target surface, wherein the ground circuit path is configured to dissipate build up of electricity when in contact with the target surface. In another aspect, the dry adhesive system can further comprise a conductive material in a backing layer. In some embodiments, the dry adhesive system can further comprise a metal backing layer.

Another aspect of the present disclosure provides a non-transitory computer readable medium comprising machine executable code that, upon execution by one or more computer processors, implements any of the methods above or elsewhere herein.

Another aspect of the present disclosure provides a system comprising one or more computer processors and computer memory coupled thereto. The computer memory comprises machine executable code that, upon execution by the one or more computer processors, implements any of the methods above or elsewhere herein.

Additional aspects and advantages of the present disclosure will become readily apparent to those skilled in this art from the following detailed description, wherein only illustrative embodiments of the present disclosure are shown and described. As will be realized, the present disclosure is capable of other and different embodiments, and its several details are capable of modifications in various obvious respects, all without departing from the disclosure. Accordingly, the drawings and description are to be regarded as illustrative in nature, and not as restrictive.

CROSS REFERENCE

This application claims the benefit of U.S. Provisional Application No. 63/145,295 filed February 3, 2021, which is incorporated herein by reference in its entirety.

INCORPORATION BY REFERENCE

All publications, patents, and patent applications mentioned in this specification are herein incorporated by reference to the same extent as if each individual publication, patent, or patent application was specifically and individually indicated to be incorporated by reference.

BRIEF DESCRIPTION OF THE DRAWINGS

The novel features of the disclosure are set forth with particularity in the appended claims. A better understanding of the features and advantages of the present disclosure will be obtained by reference to the following detailed description that sets forth illustrative embodiments, in which the principles of the disclosure are utilized, and the accompanying drawings of which:

FIG. 1 depicts a schematic view of a microsructured dry adhesive composed of electrostatic discharge (ESD) safe material. FIG. 2 depicts a cross-sectional schematic view of an example machine component utilizing an ESD-safe microstructure dry adhesive.

FIG. 3 depicts a cross-sectional view of the exemplary machine component of FIG. 2, highlighting the direction of electrical current for discharge.

FIG. 4 depicts a cross-sectional view of the exemplary machine component of FIG. 2, highlighting the important contact points / critical surfaces to facilitate prevention of anodization for ESD-safe handling.

FIG. 5A depicts a component of the exemplary machine of FIG. 4, highlighting contact point 303. FIG. 5B depicts a component of the exemplary machine of FIG. 4, highlighting contact point 301. FIG. 5C depicts a component of the exemplary machine of FIG. 4, highlighting contact point 302, 303, 304, and 305.

FIG. 6A depicts ribbed lock washers used to replace thread locks for critical surfaces of 305.

FIG. 6B depicts a cross-sectional view of the exemplary machine compontent, highlighting the location of the ribbed lock washers.

FIG. 7 depicts the component 400 and 401, wherein 401 connects to the top of the ESD-safe microstructure dry adhesive.

FIG. 8 depicts a schematic of component 401 side view, top view, bottom view, and an optical image of said component.

FIG. 9 illustrates a conceptual schematic of a computation system as provided in the present disclosure.

DETAILED DESCRIPTION

While various embodiments of the invention have been shown and described herein, it will be obvious to those skilled in the art that such embodiments are provided by way of example only. Numerous variations, changes, and substitutions may occur to those skilled in the art without departing from the invention. It should be understood that various alternatives to the embodiments of the invention described herein may be employed.

TERMINOLOGY

Various terms used throughout the present description may be read and understood as follows, unless the context indicates otherwise: “or” as used throughout is inclusive, as though written “and/or”; singular articles and pronouns as used throughout include their plural forms, and vice versa; similarly, gendered pronouns include their counterpart pronouns so that pronouns should not be understood as limiting anything described herein to use, implementation, performance, etc. by a single gender; “exemplary” should be understood as “illustrative” or “exemplifying” and not necessarily as “preferred” over other embodiments. Further definitions for terms may be set out herein; these may apply to prior and subsequent instances of those terms, as will be understood from a reading of the present description.

The term “elastomer” in the descriptions herein, refers to a material that changes properties in response to an applied force. Elastomers, in various formulations, respond to normal forces, compression, torque, or sheer stresses or forces. Some elastomers are also referred to as “rubber,” “polymer,” or “silicone.” Typically, but not always, an elastomer responds to an applied force with a physical deformation. Additionally, elastomers can be designed to change various properties such as impedance in response to applied force, stress, or torque. Elastomers can be configured to change properties when stressed in one dimension, or in multiple dimensions.

Elastomers can be formulated and produced with various properties that may be desirable for a given application, for example desired flexibility, stiffness (i.e. spring constant or dimensional change in response to pressure), conformability (i.e. ability to follow a curved or complex contour), thickness, color, or electrical or heat conductivity. Another property of an elastomer is “durometer,” which is its hardness or resistance to permanent deformation. An adhesive material of the present disclosure can comprise elastomeric material. Dry adhesive materials of the present disclosure can comprise dielectric elastomeric material, for example.

In the field of manufacturing, such as but not limited to manufacturing electronics and processors, many components and materials are sensitive to electrical discharge. Electrostatic discharge (ESD) can occur from two electically charged surfaces that come in contact or when a dielectic material receives voltage that exceeds the material’s dielectric strength. Unwanted electrostatic discharge can cause damage to ESD-sensitive components when moving the components around or during the manufacturing process that requires contact between two surfaces.

The present disclosure provides various systems for increasing adhesive strength of dry adhesives pads and mitigating electrostatic discharge. The present disclosure provides various systems for simultaneously optimizing adhesion of dry adhesive materials to various surfaces and preventing electrostatic discharge when the dry adhesive is contact with ESD sensitive materials. The present disclosure provides various systems comprising an ESD-safe, microstructured dry adhesive pad. The pad may comprise conductive additives (e.g., carbon nanotubes (CNTs)) for varying static disspative ranges for mitigation of ESD. The present disclosure provides various systems of ESD- safe microstructured dry adhesive pads further comprising a conductive backing layer (e.g., comprising conductive tape) to complete the circuit to ground.

An adhesive material of the present disclosure may comprise a substrate with any type of surface, such as a microstructured gripping surface, substantially planar gripping surface, patterned gripping surface, unpatterned gripping surface, textured gripping surface, untextured gripping surface, etc.

FIG.l illustrates an ESD-safe microstructure dry adhesive. An ESD-safe dry adhesive film 101 may comprise a microstructured composite polymer layer. The microstructures may be non- directional, such that a longitudinal axis of each microstructure is substantially normal (e.g., orthogonal) to the film layer. At the end of each microstructure comprise may comprise a ESD terminal film 100. For example, the terminal film 100 may comprise a single film that interfaces each microstructure tip of the dry adhesive film 101. Alternatively, the terminal film may comprise a plurality of sub-films that together interface each microstructure tip of the dry adhesive film. The sub-films may or may not overlap with each other. A double sided silicone tape 102 component can connect the ESD-safe dry adhesive film 101 to a silicone foam layer 103. A hole 106 allows for a conductive elastomeric via, connected to the ESD-safe dry adhesive film 101, to pass through the silicone foam 103 layer and double sided silicone tape 102. The hole may be a central hole. A foam adhesive layer 104, adjacent to the silicone foam layer 103, may be in contact with a conductive backing 105. The conductive backing may be a metal backing. When the conductive backing is connected to the main body of the gripper system 1000, e.g., by screwing the ESD-safe microstructure dry adhesive assembly on with a fastener through the hole 106, the fastener (e.g., screw) can meet the conductive via and complete the connection to the ground.

An ESD-safe dry adhesive material may comprise a component of a larger device or component. An ESD-safe dry adhesive material may be a component of a larger device or component. In some instances, the dry adhesive material may be utilized for a system such as a robotic gripping system. In some instances, a system comprising an ESD-safe dry adhesive material may comprise other elements of utility, such as, but not limited to, thermal elements, magnetic elements, electromagnetic elements, ultrasonic elements or rotational elements. FIG. 2 shows an exemplary system that employs the ESD-safe microstructure dry adhesive 1000. The exemplary components 1001, 1002, and 1003 are made of metal and houses 1000. In some embodiments, the components that houses the ESD-safe microstructure dry adhesive in FIG. 2 - 8 are made of aluminum. FIG. 3 depicts the pathway for grounding the electrical current of the exemplary system and ESD-safe microstructure dry adhesive. FIG. 4 highlights the important critical surfaces 300, 301, 303, and 304 where anodization may occur when metal components are in contact. In order to prevent anoidization, contact surfaces are insulated as seen in FIG. 5A, FIG. 5B, and FIG. 5C on 301, 302, 303, 304, and 305. Ribbed lock washers 500 as seen in FIG. 6A and FIG. 6B are used to replace thread lock and gaurentee contact between critical surfaces. FIG. 7 displays the printed circuit board aseembly (PCBA) 400, and the lOp quick change (QC) connector 401 that holds the ESD-safe microstructure dry adhesive assembly. In an example, the QC connector connected to the ESD-safe dry adhesive pad can be compressed from 1.8 milimeters (mm) to 1 mm. FIG. 8 shows a schematic of the QC connector with its dimensions and at different viewing points.

In some embodiments, the ESD-safe microstructure dry adhesives are composed of a substrate 101 and a terminal film 100 on top of a column(s). The base substrate has a microstructure of columns to increase contact area at the interface. An increased contact area at the interface can increase attractive forces (e.g., van der Waals interactions). Provided herein, the term column can be interchangeable with pillar or stalk.

Microstructures having different physical characteristics, such as in shape, size, and/or volume, can comprise different adhesive properties. In some aspects, physical characteristics, such as a shape, size, or volume, of microstructures in a dry adhesive may affect the degree of van der Waals interactions between the microstructures and a contact surface to enhance or diminish overall adhesive performance.

In some embodiments, the microstructure columns on the base substrate has a column height of about 20 pm to about 70 pm. In some embodiments, the height of the microstructure columns are about 50 pm.

In some embodiments, the microstructure columns have a length of about 10 pm to about 30 pm. In some embodiments, the microstructure columns length is about 20 pm.

In some embodiments, the microstructure column width is about 10 pm to about 30 pm. In some embodiments, the microstructure columns length is about 20 pm.

In some emboidments, the spacing between microstructure columns is about 10 pm to about 30 pm. In some embodiments, the spacing between microstructure columns is about 20 pm.

In some embodiments, the microstructure columns are cylindrical. In some embodiments, the columns are microstructure rectangular. In some embodiments, the microstructure columns are non-directional i.e. vertical with neglible angle to the column long axis. In some embodiments, the microstructure column is isotopic/uniform along the length axis. In some embodiments, the non- directional columns trap crack propogation from misalignments, irregularities of contact surface, and to cope with substract surface roughness. In some embodiments, the microstructures underneath help the terminal film conform to the microroughess on the target surface. In some embodiments, the microstructures underneath help the terminal film prevent crack proprogation created by microroughness on the target surface.

In some aspects, a change in material composition of the dry adhesive may affect mechanical properties, such as work of adhesion and modulus of elasticity (e.g., Young’s modulus), of the dry adhesive to enhance or diminish overall adhesive performance. An adhesive material may interface a target surface (e.g., that is to be adhered to). In some cases, the adhesive material comprises any solid material. In some cases, the adhesive material may demonstrate superior adhesion strength compared to a conventional material. The adhesive may comprise a dry adhesive (e.g., comprising microstructured surface(s)). The adhesive may comprise an electrostatic adhesive.

In some embodiments, the material composition of the base substrate, terminal film, or both, can be modified to Young’s modulus. In some embodiments, the material composition of the base substrate, terminal film, or both, has a low modulus for a rough surface. In some embodiments, the material composition of the base substrate, terminal film, or both, has a high modulus for a smooth surface.

For example, conductive additives can be added to the material to improve adhesive performance. For example, the conductive additives may comprise carbon nanotubes (CNTs) or carbon black. In other aspects, microstructures comprising conductive additives allow the microstructures to be conductive. In some embodiments, the base substrate is made of a polymer e.g. Sylgard 184, Dow Corning). In some embodiments, the base substrate comprises more than one polymer. In some embodiments, the base substrate comprises conductive additives e.g., Nanocyl NC7000 Multiwall carbon nanotubes (MWCNT)). In some embodiments, the base substrate composition comprises Sylgard 184 (10: 1 ratio, base polymer : catalyst), Dowsil 3-6559 at 3.33 % of total weight of Sylgard 184, and Nanocyl NC7000 MWCNT (dispersed in Chloroform 98% via sonication) at 0.733% weight of Sylgard 184.

In some embodiments, the terminal film of the ESD-safe microstructure dry adhesives comprises a polymer (e.g., Elastosil 629 rt A/B, Wacker) and a conductive additive (e.g., Nanocyl NC7000 MWCNT). In some embodiments, the material composition of the terminal film comprises Elastosil 629 rt A/B, Wacker (10: 1 ratio) and Nanocyl NC7000 MWCNT (dispersed in Chloroform 98% via sonication) at 1.2% total weight of Elastosil 629. In some embodiments, the terminal film doped with MWCNT has a conductivity of about 10⁵ ohm/cm².

In some embodiments, the terminal film has a thickness of 10 pm to about 30 pm. In some embodiments, the terminal film has a thickness of 20 pm.

In some embodiments, the ESD-safe microstructure dry adhesives is adhered to a conductive via material (silicone foam) 103. In some embodiments, the conductive via material comprises an elastomer (e.g., Ecoflex gel, Smooth-on) and a conductive additive (e.g., Nanocyl NC7000 MWCNT). In some embodiments, the conductive via material composition comprisies Ecoflex gel, Smooth-on (1 : 1 ratio) and Nanocyl NC7000 MWCNT (dispersed in Chloroform 98% via sonication) at 1.2% total weight of Ecoflex gel, Smooth-on. In some embodiments, the quantity and concentration of conductive additives (e.g., Nanocyl NC7000 MWCNT) in the base substrate, terminal film, and conductive via material (silicone foam) can be varied for desired disspative electrostatic range. In some embodiments, when the terminal film comes in contact with a substrate, the any built of electritcity immediately dissipates from the surface. In some embodiments, the terminal film interacts with a target substrate through Van der Waals forces.

In some embodiments, the the ESD-safe microstructure dry adhesive is in the form of a pad. In some embodiments, the pad size is about 35 mm to about 75mm. In some embodiments, the pad size is about 60 mm.

In some embodiments, the ESD-safe microstructure dry adhesives has an endurance lifetime of 200,000 cycles. In some embodiments, the cycle time is 0.3 s (preload, 0.1 second dwell-time, release).

DRY ADHESIVES

In some instances, the dry adhesive pad may be designed to have a particular surface roughness. Without wishing to be bound by theory, surface roughness may be defined as the average deviation in the form of a surface relative to its ideal form. In some examples, the surface roughness may represent the average height of surface structures above an average surface level. The surface roughness may be considered an intrinsic material property (i.e. artifactual of the material synthesis process) in comparison to the above-described engineering of microstructures in the dry adhesive material. Surface roughness may be determined by various surface metrology methods, including, but not limited to, confocal microscopy, interferometry, holography, scanning electron microscopy (SEM), and atomic force microscopy (AFM). A material for a dry adhesive may be chosen based upon the value of its surface roughness. A dry adhesive material may have a surface roughness of about 0.5 nanometers (nm), 1 nm, 2 nm, 3 nm, 4 nm, 5 nm, 6 nm, 7 nm, 8 nm, 9 nm, 10 nm, 15 nm, 20 nm, 25 nm, 50 nm or about 100 nm. A dry adhesive material may have a surface roughness of at least about 0.5 nanometers (nm), 1 nm, 2 nm, 3 nm, 4 nm, 5 nm, 6 nm, 7 nm, 8 nm, 9 nm, 10 nm, 15 nm, 20 nm, 25 nm, 50 nm or at least about 100 nm or more. A dry adhesive material may have a surface roughness of no more than about 100 nm, 50 nm, 25 nm, 20 nm, 15 nm, 10 nm, 9 nm, 8 nm, 7 nm, 6 nm, 5 nm, 4 nm, 3 nm, 2 nm, 1 nm, or no more than about 0.5 nm or less. A dry adhesive material may be chosen with a surface roughness in a range from about 0.5 nm to about 2 nm, about 0.5 nm to about 5 nm, about 0.5 nm to about 10 nm, about 0.5 nm to about 50 nm, about 0.5 nm to about 100 nm, about 2 nm to about 5 nm, about 2 nm to about 10 nm, about 2 nm to about 50 nm, about 2 nm to about 100 nm, about 5 nm to about 10 nm, about 5 nm to about 50 nm, about 5 nm to about 100 nm, about 10 nm to about 50 nm, about 10 nm to about 100 nm, or about 50 nm to about 100 nm.

In some instances, the dry adhesive pad may be designed to have a particular elastic modulus. In some instances, the elastic modulus may specifically refer to the Young’s modulus of a particular material. In other instances, the elastic modulus may refer to the shear modulus or bulk modulus. Without wishing to be bound by theory, the elastic modulus may be defined as the amount of deformation in a material due to an applied force or stress. In some instances, the elastic modulus may be defined as the ratio of stress to strain along an axis in a material experiencing deformation along the axis. An elastic modulus may be measured by any suitable instrument for the measurement of such mechanical properties. A material for a dry adhesive may be chosen based upon the value of its elastic modulus. A dry adhesive material may have an elastic modulus of about 0.5 megaPascals (MPa), 0.6 MPa, 0.7 MPa, 0.8 MPa, 0.9 MPa, 1.0 MPa, 1.1 MPa, 1.2 MPa,

1.3 MPa, 1.4 MPa, 1.5 MPa, 1.6 MPa, 1.7 MPa, 1.8 MPa, 1.9 MPa, 2.0 MPa, 2.1 MPa, 2.2 MPa,

2.3 MPa, 2.4 MPa, 2.5 MPa, 2.6 MPa, 2.7 MPa, 2.8 MPa, 2.9 MPa, 3.0 MPa, 5 MPa, 10 MPa, 50

MPa, or about 100 MPa. A dry adhesive material may have an elastic modulus of at least about 0.5 MPa, 0.6 MPa, 0.7 MPa, 0.8 MPa, 0.9 MPa, 1.0 MPa, 1.1 MPa, 1.2 MPa, 1.3 MPa, 1.4 MPa,

1.5 MPa, 1.6 MPa, 1.7 MPa, 1.8 MPa, 1.9 MPa, 2.0 MPa, 2.1 MPa, 2.2 MPa, 2.3 MPa, 2.4 MPa,

2.5 MPa, 2.6 MPa, 2.7 MPa, 2.8 MPa, 2.9 MPa, 3.0 MPa, 5 MPa, 10 MPa, 50 MPa, or at least about 100 MPa or more. A dry adhesive material may have an elastic modulus of no more than about 100 MPa, 50 MPa, 10 MPa, 5 MPa, 3.0 MPa, 2.9 MPa, 2.8 MPa, 2.7 MPa, 2.6 MPa, 2.5 MPa, 2.4 MPa, 2.3 MPa, 2.2 MPa, 2.1 MPa, 2.0 MPa, 1.9 MPa, 1.8 MPa, 1.7 MPa, 1.6 MPa, 1.5 MPa, 1.4 MPa, 1.3 MPa, 1.2 MPa, 1.1 MPa, 1.0 MPa, 0.9 MPa, 0.8 MPa, 0.7 MPa, 0.6 MPa, or no more than about 0.5 MPa or less. A dry adhesive material may be chosen with an elastic modulus in a range from about 0.5 MPa to about 1.0 MPa, about 0.5 MPa to about 1.5 MPa, about 0.5 MPa to about 2.0 MPa, about 0.5 MPa to about 2.5 MPa, about 0.5 MPa to about 3.0 MPa, about 0.5 MPa to about 10 MPa, about 1.0 MPa to about 1.5 MPa, about 1.0 MPa to about 2.0 MPa, about 1.0 MPa to about 2.5 MPa, about 1.0 MPa to about 3.0 MPa, about 1.0 MPa to about 10 MPa, about 1.5 MPa to about 2.0 MPa, about 1.5 MPa to about 2.5 MPa, about 1.5 MPa to about 3.0 MPa, about 1.5 MPa to about 10 MPa, about 2.0 MPa to about 2.5 MPa, about 2.0 MPa to about 3.0 MPa, about 2.0 MPa to about 10 MPa, about 2.5 MPa to about 3.0 MPa, about 2.5 MPa to about 10 MPa, or about 3.0 MPa to about 10 MPa.

In some instances, a dry adhesive may be characterized by a work of adhesion. Without wishing to be bound by theory, a work of adhesion may be defined as the free energy change when an interface is broken between two materials. A dry adhesive material may have a work of adhesion of about 0.5 milli Joules per square meter (mJ/m2), 1 mJ/m2, 2 mJ/m2, 3 mJ/m2, 4 mJ/m2, 5 mJ/m2, 6 mJ/m2, 7 mJ/m2, 8 mJ/m2, 9 mJ/m2, 10 mJ/m2, 11 mJ/m2, 12 mJ/m2, 13 mJ/m2, 14 mJ/m2, 15 mJ/m2, 16 mJ/m2, 17 mJ/m2, 18 mJ/m2, 19 mJ/m2, 20 mJ/m2, 30 mJ/m2, 40 mJ/m2, or about 50 mJ/m2. A dry adhesive material may have a work of adhesion of at least about 0.5 mJ/m2, 1 mJ/m2, 2 mJ/m2, 3 mJ/m2, 4 mJ/m2, 5 mJ/m2, 6 mJ/m2, 7 mJ/m2, 8 mJ/m2, 9 mJ/m2,

10 mJ/m2, 11 mJ/m2, 12 mJ/m2, 13 mJ/m2, 14 mJ/m2, 15 mJ/m2, 16 mJ/m2, 17 mJ/m2, 18 mJ/m2, 19 mJ/m2, 20 mJ/m2, 30 mJ/m2, 40 mJ/m2, or at least about 50 mJ/m2 or more. A dry adhesive material may have a work of adhesion of no more than about 50 mJ/m2, 40 mJ/m2, 30 mJ/m2, 20 mJ/m2, 19 mJ/m2, 18 mJ/m2, 17 mJ/m2, 16 mJ/m2, 15 mJ/m2, 14 mJ/m2, 13 mJ/m2, 12 mJ/m2,

11 mJ/m2, 10 mJ/m2, 9 mJ/m2, 8 mJ/m2, 7 mJ/m2, 6 mJ/m2, 5 mJ/m2, 4 mJ/m2, 3 mJ/m2, 2 mJ/m2, 1 mJ/m2, or no more than about 0.5 mJ/m2 or less.

In some instances, a dry adhesive material may be characterized by a work of separation. Without wishing to be bound by theory, a work of separation may be defined as the reversible work necessary to break an interface between two materials. A dry adhesive material may have a work of separation of about 50 mJ/m2, 75 mJ/m2, 100 mJ/m2, 110 mJ/m2, 120 mJ/m2, 130 mJ/m2, 140 mJ/m2, 150 mJ/m2, 160 mJ/m2, 170 mJ/m2, 180 mJ/m2, 190 mJ/m2, 200 mJ/m2, 250 mJ/m2, 300 mJ/m2, or about 400 mJ/m2. A dry adhesive material may have a work of separation of at least about 50 mJ/m2, 75 mJ/m2, 100 mJ/m2, 110 mJ/m2, 120 mJ/m2, 130 mJ/m2, 140 mJ/m2, 150 mJ/m2, 160 mJ/m2, 170 mJ/m2, 180 mJ/m2, 190 mJ/m2, 200 mJ/m2, 250 mJ/m2, 300 mJ/m2, or at least about 400 mJ/m2 or more. A dry adhesive material may have a work of separation of no more than about 400 mJ/m2, 300 mJ/m2, 250 mJ/m2, 200 mJ/m2, 190 mJ/m2, 180 mJ/m2, 170 mJ/m2, 160 mJ/m2, 150 mJ/m2, 140 mJ/m2, 130 mJ/m2, 120 mJ/m2, 110 mJ/m2, 100 mJ/m2, 75 mJ/m2, or no more than about 50 mJ/m2 or less.

The separation shear stress strength of a dry adhesive material may be correlated to one or more physical properties of the material. In some instances, the separation shear stress strength of a microstructured dry adhesive with a smooth surface, such as glass, may be predicted by a power law relationship. In a particular instance, the separation shear stress strength of a microstructured dry adhesive with a smooth glass surface may correlate with the square root of the product of the material’s work of separation and elastic modulus. In some instances, the separation shear strength of a dry adhesive material may agree with a predictive model, for example Kendall’s peeling model. Adhesion between a dry adhesive material and another material may be characterized by the stress required to break the interface between the two materials. In some instances, the adhesion strength between a dry adhesive material and another material may be characterized by a separation shear strength. A separation shear strength may be characterized by the load necessary to break the interface between two materials when the load is applied parallel to the interface. In other instances, the adhesion strength between a dry adhesive material and another material may be characterized by a normal strength. A normal strength may be characterized by the tension load necessary to break the interface between two materials when the load is applied in an orthogonal direction to the interface. The strength of adhesion may also be characterized by other methods, such as combined normal and shear stresses, e.g., via rotational loading around an axis parallel to the interface.

A normal stress strength may be measured to characterize the strength of adhesion of a dry adhesive material. The normal stress may be a function of the properties of the dry adhesive material and the properties of the material to which the adhesive is adhered. For example, a dry adhesive material may have a lower normal stress strength when adhered to a rough or non-planar surface than when adhered to a smoother or more planar surface. The normal stress strength of a dry adhesive material may be measured by mechanical testing. In some cases, the normal stress strength of the dry adhesive material adhered with another material may be about 0.01 kiloPascals (kPa), 0.1 kPa, 0.2 kPa, 0.3 kPa, 0.4 kPa, 0.5 kPa, 0.6 kPa, 0.7 kPa, 0.8 kPa, 0.9 kPa, 1 kPa, 2 kPa, 3 kPa, 4 kPa, 5 kPa, 6 kPa, 7 kPa, 8 kPa, 9 kPa, 10 kPa, 11 kPa, 12 kPa, 13 kPa, 14 kPa, 15 kPa, 16 kPa, 17 kPa, 18 kPa, 19 kPa, 20 kPa, 30 kPa, 40 kPa, or about 50 kPa. In some cases, the normal stress strength of the dry adhesive material adhered with another material may be at least about 0.01 kPa, 0.1 kPa, 0.2 kPa, 0.3 kPa, 0.4 kPa, 0.5 kPa, 0.6 kPa, 0.7 kPa, 0.8 kPa, 0.9 kPa, 1 kPa, 2 kPa, 3 kPa, 4 kPa, 5 kPa, 6 kPa, 7 kPa, 8 kPa, 9 kPa, 10 kPa, 11 kPa, 12 kPa, 13 kPa, 14 kPa, 15 kPa, 16 kPa, 17 kPa, 18 kPa, 19 kPa, 20 kPa, 30 kPa, 40 kPa, or at least about 50 kPa or more. In some cases, the normal stress strength of the dry adhesive material adhered with another material may be no more than about 50 kPa, 40 kPa, 30 kPa, 20 kPa, 19 kPa, 18 kPa, 17 kPa, 16 kPa, 15 kPa, 14 kPa, 13 kPa, 12 kPa, 11 kPa, 10 kPa, 9 kPa, 8 kPa, 7 kPa, 6 kPa, 5 kPa, 4 kPa, 3 kPa, 2 kPa, 1 kPa, 0.9 kPa, 0.8 kPa, 07 kPa, 0.6 kPa, 0.5 kPa, 0.4 kPa, 0.3 kPa, 0.2 kPa, 0.1 kPa, or no more than about 0.01 kPa or less.

The magnitude of a dry adhesive material’s normal stress strength may be altered by physical or chemical changes to the material. In some instances, accumulation of particulate matters, fouling by chemicals, physical damage, chemical degradation, or other changes to the dry adhesive material may alter (e.g., reduce) the ability of the dry adhesive to adhere to other materials. In other instances, electroactuation of the dry adhesive surface by an electric field may increase the normal stress strength of the dry adhesive material. The change in the normal stress strength of a dry adhesive material due to physical or chemical alteration may be expressed as a percentage change in the normal stress between the altered material and the pristine material. In some instances, the altered dry adhesive material normal stress strength may be about 5%, 10%, 20%, 30%, 40%, 50%, 60%, 70%, 80%, 90%, 100%, 110%, 120%, 150%, or about 200% of the pristine normal stress strength. In some instances, the altered dry adhesive material normal stress strength may be at least about 5%, 10%, 20%, 30%, 40%, 50%, 60%, 70%, 80%, 90%, 100%, 110%, 120%, 150%, or at least about 200% or more of the pristine normal stress strength. In some instances, the altered dry adhesive material normal stress strength may be no more than about 200%, 150%, 120%, 110%, 100%, 90%, 80%, 70%, 60%, 50%, 40%, 30%, 20%, 10%, or no more than about 5% or less of the pristine normal stress strength.

The magnitude of a dry adhesive material’s separation shear stress strength may be altered by physical or chemical changes to the material. In some instances, accumulation of particulate matters, fouling by chemicals, physical damage, chemical degradation, or other changes to the dry adhesive material may alter (e.g., reduce) the ability of the dry adhesive to adhere to other materials. In other instances, electroactuation of the dry adhesive surface by an electric field may increase the separation shear stress strength of the dry adhesive material. The change in the separation shear stress strength of a dry adhesive material due to physical or chemical alteration may be expressed as a percentage change in the shear stress between the altered material and the pristine material. In some instances, the altered dry adhesive material separation shear stress strength may be about 5%, 10%, 20%, 30%, 40%, 50%, 60%, 70%, 80%, 90%, 100%, 110%, 120%, 150%, or about 200% of the pristine separation shear stress strength. In some instances, the altered dry adhesive material separation shear stress strength may be at least about 5%, 10%, 20%, 30%, 40%, 50%, 60%, 70%, 80%, 90%, 100%, 110%, 120%, 150%, or at least about 200% or more of the pristine separation shear stress strength. In some instances, the altered dry adhesive material separation shear stress strength may be no more than about 200%, 150%, 120%, 110%, 100%, 90%, 80%, 70%, 60%, 50%, 40%, 30%, 20%, 10%, or no more than about 5% or less of the pristine separation shear stress strength.

A separation shear stress strength may be measured to characterize the strength of adhesion of a dry adhesive material. The separation shear stress may be a function of the properties of the dry adhesive material and the properties of the material to which the adhesive is adhered. For example, a dry adhesive material may have a lower separation shear stress strength when adhered to a rough or non-planar surface than when adhered to a smoother or more planar surface. The separation shear stress strength of a dry adhesive material may be measured by mechanical testing. The separation shear stress strength of a dry adhesive material adhered with another material may be about 1 kPa, 5 kPa, 10 kPa, 15 kPa, 20 kPa, 25 kPa, 30 kPa, 35 kPa, 40 kPa, 45 kPa, 50 kPa, 55 kPa, 60 kPa, 65 kPa, 70 kPa, 80 kPa, 85 kPa, 90 kPa, 100 kPa, 150 kPa, or about 200 kPa. The separation shear stress strength of a dry adhesive material adhered with another material may be at least about 1 kPa, 5 kPa, 10 kPa, 15 kPa, 20 kPa, 25 kPa, 30 kPa, 35 kPa, 40 kPa, 45 kPa, 50 kPa, 55 kPa, 60 kPa, 65 kPa, 70 kPa, 80 kPa, 85 kPa, 90 kPa, 100 kPa, 150 kPa, or at least about 200 kPa or more. The separation shear stress strength of a dry adhesive material adhered with another material may be no more than about 200 kPa, 150 kPa, 100 kPa, 90 kPa, 85 kPa, 80 kPa, 75 kPa, 70 kPa, 65 kPa, 60 kPa, 55 kPa, 50 kPa, 45 kPa, 40 kPa, 35 kPa, 30 kPa, 25 kPa, 15 kPa, 10 kPa, 5 kPa, or no more than about 1 kPa or less.

Computer systems

The present disclosure provides computer control systems that are programmed to implement methods of the disclosure. FIG. 9 shows a computer system 201 that is programmed or otherwise configured to dissipate electrostatic discharge by manipulating an ESD-safe dry adhesive. The computer system 201 can regulate various aspects of the present disclosure, such as, for example, varying the disspative range. The computer system 201 can be an electronic device of a user or a computer system that is remotely located with respect to the electronic device. The electronic device can be a mobile electronic device.

The computer system 201 includes a central processing unit (CPU, also “processor” and “computer processor” herein) 205, which can be a single core or multi core processor, or a plurality of processors for parallel processing. The computer system 201 also includes memory or memory location 210 (e.g., random-access memory, read-only memory, flash memory), electronic storage unit 215 (e.g., hard disk), communication interface 220 (e.g., network adapter) for communicating with one or more other systems, and peripheral devices 225, such as cache, other memory, data storage and/or electronic display adapters. The memory 210, storage unit 215, interface 220 and peripheral devices 225 are in communication with the CPU 205 through a communication bus (solid lines), such as a motherboard. The storage unit 215 can be a data storage unit (or data repository) for storing data. The computer system 201 can be operatively coupled to a computer network (“network”) 230 with the aid of the communication interface 220. The network 230 can be the Internet, an internet and/or extranet, or an intranet and/or extranet that is in communication with the Internet. The network 230 in some cases is a telecommunication and/or data network. The network 230 can include one or more computer servers, which can enable distributed computing, such as cloud computing. The network 230, in some cases with the aid of the computer system 201, can implement a peer-to-peer network, which may enable devices coupled to the computer system 201 to behave as a client or a server. The CPU 205 can execute a sequence of machine-readable instructions, which can be embodied in a program or software. The instructions may be stored in a memory location, such as the memory 210. The instructions can be directed to the CPU 205, which can subsequently program or otherwise configure the CPU 205 to implement methods of the present disclosure. Examples of operations performed by the CPU 205 can include fetch, decode, execute, and writeback.

The CPU 205 can be part of a circuit, such as an integrated circuit. One or more other components of the system 201 can be included in the circuit. In some cases, the circuit is an application specific integrated circuit (ASIC).

The storage unit 215 can store files, such as drivers, libraries and saved programs. The storage unit 215 can store user data, e.g., user preferences and user programs. The computer system 201 in some cases can include one or more additional data storage units that are external to the computer system 201, such as located on a remote server that is in communication with the computer system 201 through an intranet or the Internet.

The computer system 201 can communicate with one or more remote computer systems through the network 230. For instance, the computer system 201 can communicate with a remote computer system of a user (e.g., a user controlling a system implementing the ESD-safe dry adhesive for gripping an ESD-sensitive component). Examples of remote computer systems include personal computers (e.g., portable PC), slate or tablet PC’s (e.g., Apple® iPad, Samsung® Galaxy Tab), telephones, Smart phones (e.g., Apple® iPhone, Android-enabled device, Blackberry®), or personal digital assistants. The user can access the computer system 201 via the network 230.

Methods as described herein can be implemented by way of machine (e.g., computer processor) executable code stored on an electronic storage location of the computer system 201, such as, for example, on the memory 210 or electronic storage unit 215. The machine executable or machine readable code can be provided in the form of software. During use, the code can be executed by the processor 205. In some cases, the code can be retrieved from the storage unit 215 and stored on the memory 210 for ready access by the processor 205. In some situations, the electronic storage unit 215 can be precluded, and machine-executable instructions are stored on memory 210. The code can be pre-compiled and configured for use with a machine having a processor adapted to execute the code, or can be compiled during runtime. The code can be supplied in a programming language that can be selected to enable the code to execute in a pre-compiled or as- compiled fashion.

Aspects of the systems and methods provided herein, such as the computer system 201, can be embodied in programming. Various aspects of the technology may be thought of as “products” or “articles of manufacture” typically in the form of machine (or processor) executable code and/or associated data that is carried on or embodied in a type of machine readable medium. Machineexecutable code can be stored on an electronic storage unit, such as memory (e.g., read-only memory, random-access memory, flash memory) or a hard disk. “Storage” type media can include any or all of the tangible memory of the computers, processors or the like, or associated modules thereof, such as various semiconductor memories, tape drives, disk drives and the like, which may provide non-transitory storage at any time for the software programming. All or portions of the software may at times be communicated through the Internet or various other telecommunication networks. Such communications, for example, may enable loading of the software from one computer or processor into another, for example, from a management server or host computer into the computer platform of an application server. Thus, another type of media that may bear the software elements includes optical, electrical and electromagnetic waves, such as used across physical interfaces between local devices, through wired and optical landline networks and over various air-links. The physical elements that carry such waves, such as wired or wireless links, optical links or the like, also may be considered as media bearing the software. As used herein, unless restricted to non-transitory, tangible “storage” media, terms such as computer or machine “readable medium” refer to any medium that participates in providing instructions to a processor for execution.

Hence, a machine readable medium, such as computer-executable code, may take many forms, including but not limited to, a tangible storage medium, a carrier wave medium or physical transmission medium. Non-volatile storage media include, for example, optical or magnetic disks, such as any of the storage devices in any computer(s) or the like, such as may be used to implement the databases, etc. shown in the drawings. Volatile storage media include dynamic memory, such as main memory of such a computer platform. Tangible transmission media include coaxial cables; copper wire and fiber optics, including the wires that comprise a bus within a computer system. Carrier-wave transmission media may take the form of electric or electromagnetic signals, or acoustic or light waves such as those generated during radio frequency (RF) and infrared (IR) data communications. Common forms of computer-readable media therefore include for example: a floppy disk, a flexible disk, hard disk, magnetic tape, any other magnetic medium, a CD-ROM, DVD or DVD-ROM, any other optical medium, punch cards paper tape, any other physical storage medium with patterns of holes, a RAM, a ROM, a PROM and EPROM, a FLASH-EPROM, any other memory chip or cartridge, a carrier wave transporting data or instructions, cables or links transporting such a carrier wave, or any other medium from which a computer may read programming code and/or data. Many of these forms of computer readable media may be involved in carrying one or more sequences of one or more instructions to a processor for execution. The computer system 201 can include or be in communication with an electronic display 1135 that comprises a user interface (UI) 240 for providing, for example, parameters for mechanical movement (e.g., compressive force) of the ESD-safe dry adhesive pad. Examples of UEs include, without limitation, a graphical user interface (GUI) and web-based user interface.

Methods and systems of the present disclosure can be implemented by way of one or more algorithms. An algorithm can be implemented by way of software upon execution by the central processing unit 205. The algorithm can, for example, can regulate the amount of compression the lOp QC connector with ESD-dry adhesive pad contacting to ESD-sensitive surfaces.

Disclosed herein are systems for comprising dry adhesive microstructures for electrostatic discharge (ESD) safe handling of ESD sensitive material. A conductive terminal film may be adjacent to the tips of of the microstructures to interface with the contact surface. In some aspects, a change in material composition of the microstructures in a dry adhesive may affect mechanical and electical properties to enhance or diminish overall adhesive performance and electical discharge performance. While preferred embodiments of the present invention have been shown and described herein, it will be obvious to those skilled in the art that such embodiments are provided by way of example only. It is not intended that the invention be limited by the specific examples provided within the specification. While the invention has been described with reference to the aforementioned specification, the descriptions and illustrations of the embodiments herein are not meant to be construed in a limiting sense. Numerous variations, changes, and substitutions will now occur to those skilled in the art without departing from the invention. Furthermore, it shall be understood that all aspects of the invention are not limited to the specific depictions, configurations or relative proportions set forth herein which depend upon a variety of conditions and variables. It should be understood that various alternatives to the embodiments of the invention described herein may be employed in practicing the invention. It is therefore contemplated that the invention shall also cover any such alternatives, modifications, variations or equivalents. It is intended that the following claims define the scope of the invention and that methods and structures within the scope of these claims and their equivalents be covered thereby.

Claims

CLAIMS A dry adhesive system, comprising: a substrate comprising a surface having a plurality of microstructures, wherein the substrate and the plurality of microstructures comprises a conductive additive; a terminal film adjacent to the plurality of microstructures, wherein a surface of the terminal film is configured to interface a target surface, wherein the terminal film comprises the conductive additive or an additional conductive additive, and wherein the dry adhesive system comprises a ground circuit path from the terminal film to a ground, wherein the ground circuit path is configured to dissipate electrostatic charge when in contact with the target surface. The dry adhesive system of claim 1, wherein the substrate further comprises a conductive material in a backing layer. The dry adhesive system of claim 2, wherein the conductive material in the backing layer comprises a metal. The dry adhesive system of any one of claims 1-3, wherein the terminal film comprises a single film. The dry adhesive system of any one of claims 1-3, wherein the terminal film comprises a plurality of sub-films, wherein the sub-films together are configured to interface a target surface. The dry adhesive system of claim 5, wherein the sub-films overlap with each other. The dry adhesive system of claim 5, wherein the sub-films do not overlap with each other. The dry adhesive system of any one of claims 1-7, wherein the plurality of microstructures are oriented such that a longitudinal axis of each microstructure in the plurality of microstructures is substantially normal to the terminal film. The dry adhesive system of claim 1, wherein the plurality of microstructures forms one or more columns to increase contact area for interfacing the target surface. The dry adhesive system of claim 9, wherein the one or more columns have a height of between about 10 pm and about 30 pm. The dry adhesive system of claims 9 or 10, wherein the one or more columns have a width of between about 10 pm and about 30 pm. The dry adhesive system of any one of claims 9-11, wherein the one or more columns comprises a spacing of between about 10 pm and about 30 pm. The dry adhesive system of any one of claims 9-12, wherein the one or more columns are cylindrical. The dry adhesive system of any one of claims 9-12, wherein the one or more columns are rectangular. The dry adhesive system of any one of claims 9-14, wherein the one or more columns are substantially vertical with neglible angle to the long axis of the one or more columns. The dry adhesive system of any one of claims 9-15, wherein a cross-sectional shape of each column in the one or more columns is substantially uniform along the long axis of the one or more columns. The dry adhesive system of any one of claims 9-16, wherein the one or more columns are configured to trap crack propagation from misalignments or irregularities of the target surface. The dry adhesive system of any one of claims 9-17, wherein the plurality of microstructures are configured to conform to microstructures on the target surface. The dry adhesive system of any one of claims 9-18, wherein the plurality of microstructures are configured to prevent crack propagation created by microstructures on the target surface. The dry adhesive system of any one of claims 1-19, wherein the conductive additive comprises carbon nanotubes or carbon black. The dry adhesive system of any one of claims 1-20, wherein the terminal film comprises a polymer. The dry adhesive system of any one of claims 1-21, wherein the terminal film has a thickness of between about 10 pm and about 30 pm. The dry adhesive system of any one of claims 1-22, wherein the dry adhesive system is a pad. The dry adhesive system of claim 23, wherein the pad is about 35 mm to about 75 mm in one dimension. The dry adhesive system of any one of claims 1-23, wherein the dry adhesive system has an endurance lifetime of about 200,000 cycles. The dry adhesive system of claim 25, wherein the cycle time is about 0.3 seconds. The dry adhesive system of any one of claims 1-26, wherein the dry adhesive system has a surface roughness of between about 0.5 nm and 100 nm. The dry adhesive system of any one of claims 1-27, wherein the terminal film has a work of adhesion of between about 0.5 mJ/m² and 50 mJ/rn². The dry adhesive system of any one of claims 1-27, wherein the dry adhesive system has a work of separation of between about 50 mJ/m² and 400 mJ/m². The dry adhesive system of any one of claims 1-29, wherein a normal stress strength of the terminal film when the terminal film is adhered with the target surface is between about 0.01 kPa and 50 kPa. The dry adhesive system of claim 30, wherein the normal stress strength of the terminal film is substantially the same after at least 200,000 cycles. The dry adhesive system of claim 30, wherein the normal stress strength of the terminal film is substantially the same after at least 500,000 cycles. The dry adhesive system of any one of claims 1-32, wherein the separation shear stress of the terminal film when the terminal film is adhered with the target surface is between about 1 kPa and about 200 kPa.

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