Devices and methods involving microstructured structures and force sensors

Abstract

In certain examples, methods and semiconductor structures are directed to a force-sensing apparatus (e.g., synthetic skin) comprising an electrode layer and a plurality of deformation-recoverable microstructures in a dielectric region adjacent the electrode layer. In various examples, the deformation-recoverable microstructures are at randomly configured (e.g., in terms of morphology and / or spatial distribution) and, as in a capacitive-type sensor, the dielectric region may include a dielectric layer between a pair of electrode layers and with the dielectric layer and / or at least one of the electrode layers having such deformation- recoverable microstructures integrated into a surface and extending in a direction to sense forces applied towards or against the force-sensing apparatus.

Description

STFD.466PCT (S21-329) 1DEVICES AND METHODS INVOLVING MICROSTRUCTURED STRUCTURES AND FORCE SENSORSBACKGROUND[0001 J Aspects of various embodiments are directed to apparatuses, systems and methods involving microstructured structures integrated as part of force sensors. In exemplary7contexts, aspects of the present disclosure concern microstructured structures for and / or integrated as part of force sensors involving applications including (but not limited to) industrial production, automobile safety, robotic interfaces, virtual and augmented reality, health monitoring, and medical diagnostics and therapies. Pressure sensors have been widely used in such applications. Among these applications, imparting robots and prosthetics with human-like touch sensation has been of significant interest. Sensors involving human-like touch sensation are important for advancing attributes for promoting safer interactions between humans and robots, enhancing teleoperation performance, enabling interactive learning, and supporting elderly care and patient rehabilitation.(0002) Despite notable recent advancements in robotic control and learning using optical-based technologies, such as cameras and Lidar (e.g., light detection and ranging) devices, performing natural and dexterous operation remains challenging, which limits adoption and widespread use of robots in non-structured human-centric environments. Indeed, the interaction between robots and their surroundings is often constrained by the lack of adequate tactile sensing, where only scarce force information at limited locations is available through contact. On the contrary, biological human skin represents a highly- distributed sensing network with mechanoreceptors spread over large areas, providing unparalleled spatiotemporal tactile awareness for complex actions. 0003] For many applications, it is highly desirable to better quantify, understand, and emulate human touch sensation, thereby rendering large-scale electronic skin capable of sensing dynamic tactile interactions. For example, advancements might be realized if such electronic skin could conformally cover large areas and possess characteristics, such as skinlike softness, tailorable performance, broad dynamic ranges, high sensitivities, low hysteresis, fast response and recovery, cyclic stability, and / or three-dimensional (3D) sensing capability on curvilinear surfaces. However, practicable realization of such large-scale sensory systems has proven difficult due to stringent requirements posed on material preparation, device fabrication, and system-level integration. Furthermore, rapid adjustment of electronic skinSTFD.466PCT (S21-329) 2 designs (e.g., sensor distribution and density) for vanous applications has been challenging due to the lack of easily-adaptable manufacturing methods.

[0004] One ty pe of high-performance sensor is known as a capacitive pressure sensor. Capacitive pressure sensors are attractive due to their simple device configuration, fast response, high sensitivity, temperature insensitivity, and low power consumption. The sensor’s capacitance (C) is governed as a function of the electrode area (capacitive pressure sensor), the relative permittivity7(s) of the dielectric between the electrodes, and the separation distance (d) between the electrodes. The equation C=A&d is sometimes applicable in characterizing certain exemplary capacitive pressure sensors. Upon receiving a pressure in such sensors, the dielectric is deformed, causing a decrease in d, sometimes accompanied with increase in e and / or A, which leads to an increase in the sensor’s capacitance (C).

[0005] While various manufacturing methods have been pursued to improve the sensitivities of such capacitive pressure sensors, these methods have fallen somewhat short of expectations as they cannot be rapidly prototy ped and / or achieve high resolution for large- scale personalized e-skins. For example, it has remained extremely challenging to apply a single manufacturing approach for microstructural engineering of soft capacitive pressure sensor components with highly customizable characteristics. This is of particular importance for understanding human-human and human-robot interactions, where personalized e-skin may be required for individuals or meet the demands of changing requirements.

[0006] Accordingly, there are real needs for materials and manufacturing methods which would lead to high-performance materials and / or customizable pressure-sensitive electronic skins for use in large-scale implementations.SUMMARY OF VARIOUS ASPECTS AND EXAMPLES

[0007] Various aspects and examples according to the present disclosure (including the Appendices) are directed to issues such as those addressed above and / or others which may become apparent from the following disclosure. 0008] Exemplary7aspects of the present disclosure are related to methods, materials and semiconductor structures in the form of a force-sensing apparatus (e.g., synthetic skin), with the force-sensing apparatus being implemented as one or more of a capacitive pressure sensor, a piezoresistive pressure sensor, and more generally a force sensor to sense: pressure forces (e.g., largely involving a downw ard or orthogonally-directed force), shear forces, and / or vibrations. According to the present disclosure, the apparatus includes: an electrode layer and a plurality of deformation-recoverable microstructures in a dielectric regionSTFD.466PCT (S21-329) 3 adjacent the electrode layer. In various more specific examples, the deformation-recoverable microstructures are randomly configured (e.g., pseudo-randomly in terms of morphology and / or spatial distribution) and, as in a capacitive-ty pe sensor, the dielectric region may include a dielectric layer between a pair of electrode layers and with the dielectric layer and / or at least one of the electrode layers having such deformation-recoverable microstructures integrated into a surface and extending in a direction to sense forces applied towards or against the force-sensing apparatus.

[0009] Certain specific example embodiments and aspects of the present disclosure are directed to capacitive pressure sensors which provide fast response, high sensitivity’, temperature insensitivity, and / or low power consumption. In such example embodiments, the sensor’s capacitance (C) is governed by the equation: C=As / d, where A is the electrode area, eis the relative permittivity of the dielectric, and d is the electrode separation distance. Upon receiving a pressure, the dielectric is deformed, causing a decrease in d. sometimes accompanied with increase in s mA! x A. which leads to an increase in the sensor’s capacitance (C). To improve the sensitivity' and reduce the hysteresis, microstructured dielectrics and / or electrodes are implemented in accordance with certain example embodiments and aspects of the present disclosure, by one or more of several methods, including (1) photolithography (e.g., micro-patterned pyramids, ridges, and domes), (2) replicating pre-existing surface textures (e.g., lotus leaves, sandpapers, and micro-lenses), (3) forming micropores using sacrificial agents (e.g., removable particles upon dissolution, and foams), and (4) direct 3D printing (e.g., lattices). 0010] In certain other (related) specific example embodiments, aspects of the present disclosure involve a digital laser writing, sometimes referred to as laser-assisted direct ink writing (or DiLW), which is a 3D printing method that combines direct ink writing with laser annealing to create desired structures as exemplified by the electrode and / or dielectric layers of FIG. 1A. According to the present disclosure, a DiLW approach may be used for manufacturing large-scale capacitive pressure-sensing electronic skin with low modulus, excellent stretchability, high sensing performance, and customizability for personalization. In connection with the experimental efforts leading to the present disclosure, it has been discovered that a previously unexplored feature of DiLW (i.e., its ability to generate surface textures under high-speed rastering) can be used for producing microstructured dielectric and electrodes for making highly sensitive components for capacitive pressure sensors with tunable sensitivity, size and distribution on-demand.STFD.466PCT (S21-329) 4

[0011] In another example, the present disclosure is directed to an apparatus (e.g., system, circuitry, etc.) and methods involving such an apparatus, that includes DiLW- produced microstructured capacitive pressure sensors which exhibit favorable characteristics including broad dynamic ranges (over 560 kPa = 5.7 kg / cm2) while having high sensitivity in small-pressure regime (up to approximately 0.0443 kPa'1down to xx Pa = xx g / cm2), with nearly instantaneous response and recovery, low hysteresis comparable to commercial plastic rigid sensors (approximately 5%), and negligible performance drift after repeated cycles (>9,000 cycles), with the sensors’ performance easily tailorable by controlling laser parameters. Digital fabrication, consistent with examples of the present disclosure, allows quick iteration for development of multiplexed soft pressure sensor arrays with distributed sensing capabilities at very low costs (from both materials and equipment aspects), and can be further extended for sensor designs with high spatial density (approximately 5,057 pixels / cm2, exceeding human fingertip mechanoreceptors density of up to 250 units / cm2) and across a broad size range (e.g., greater than 25 meters).

[0001] In other, related specific example embodiments, aspects of the present disclosure involve two straightforward routes to achieve large-scale electronic skin for full-hand tactile perception (DigiSkin), which has previously been a challenge in robotics and prosthetics. In one example, large-area wearable electronic skin is digitally manufactured in one go with high customizability (e.g., of pixel size, density, arrangement, and pattern), enabling the wearer to freely grasp objects while gathering spatiotemporal tactile information. In another example, full-hand sensor coverage is achieved on a humanoid robotic hand via 3D modular fabrication, allowing the detection of sub-millimeter small features and facilitating dynamic social interactions with unprecedented 3D tactile awareness.

[0013] The above discussion is not intended to describe each aspect, embodiment or every implementation of the present disclosure. The figures and detailed description that follow also exemplify various embodiments.STFD.466PCT (S21-329) 5BRIEF DESCRIPTION OF FIGURES

[0014] Various example embodiments, including experimental examples, may be more completely understood in consideration of the following detailed description in connection with the accompanying drawings, each in accordance with the present disclosure, in which: [0015 J FIG. 1 A is a perspective view of an electronic- or synthetic-skin example embodiment including deformation-recoverable microstructures integrated into a layered structure, according to the present disclosure;

[0016] FIG. IB is another perspective view of an electronic-patch or synthetic-skin example embodiment including deformation-recoverable microstructures integrated into a layered structure, also according to the present disclosure

[0017] FIG. 2A is a set of exemplary structures (SI, S2 and S3), the latter two of which are example embodiments, according to the present disclosure;

[0018] FIGs. 2B-2H are respective graphs showing attributes of the example embodiments shown in FIG. 2A, according to certain aspects and embodiments of the present disclosure;

[0019] FIGs. 3 A, 3B and 3C showing exemplary7engineering attributes consistent with certain embodiments of the present disclosure, and FIGs. 3D and 3E show certain example embodiments of the present disclosure for spanning different exemplary areas to be sensed;

[0020] FIGs. 4A-4D show exemplary attributes, consistent with certain embodiments of the present disclosure, of deformation-recoverable microstructures;

[0021] FIGs. 5A-5B also show exemplary' attributes, consistent with certain embodiments of the present disclosure, of deformation-recoverable microstructures;

[0022] FIGs. 6A-6D show exemplary aspects, consistent with certain embodiments of the present disclosure, involving the fabrication of deformation-recoverable microstructures for production of an electrode layer;

[0023] FIGs. 7A-7F show exemplary aspects, consistent with certain embodiments of the present disclosure, involving the fabrication of deformation-recoverable microstructures for production of a dielectric layer;

[0024] FIGs. 8A-8D show exemplary' attributes, consistent with certain embodiments of the present disclosure, of a multiplexed type of capacitive pressure sensor including deformation-recoverable microstructures in electrode material and / or dielectric material;

[0025] FIGs. 9A-9C show exemplary aspects, consistent with certain embodiments of the present disclosure, of capacitive pressure sensors including different configurations of multilayered dielectric portions having deformation-recoverable microstructures;STFD.466PCT (S21-329) 6{0026] FIGs. 10A-10C show exemplary attributes, consistent with certain embodiments of the present disclosure, of piezoresistive pressure sensors including different configurations of deformation-recoverable microstructures in electrode material; and

[0027] FIGs. 11A-11C show exemplary' feature-size attributes, consistent with certain embodiments of the present disclosure, of piezoresistive pressure sensors.

[0028] While various embodiments discussed herein are amenable to modifications and alternative forms, aspects thereof have been show n by w ay of example in the drawings and will be described in detail. It should be understood, however, that the intention is not to limit the disclosure to the particular embodiments described. On the contrary, the intention is to cover all modifications, equivalents, and alternatives falling within the scope of the disclosure including aspects defined in the claims. In addition, the term “example” as used throughout this application is only by way of illustration, and not limitation.DETAILED DESCRIPTION

[0029] Aspects of the present disclosure are believed to be applicable to a variety of different types of apparatuses, systems and methods involving force-sensing devices characterized at least in part by microstructures integrated within such devices as part of one or multiple electrodes, for example, in a dielectric region and / or material between electrode layers. While the present disclosure is not necessarily limited to such aspects, an understanding of specific examples in the following description may be understood from discussion in such specific contexts.

[0030] Accordingly, in the following description various specific details are set forth to describe specific examples presented herein. It should be apparent to one skilled in the art, however, that one or more other examples and / or variations of these examples may be practiced without all the specific details given below. In other instances, well known features have not been described in detail so as not to obscure the description of the examples herein. For ease of illustration, the same connotation and / or reference numerals may be used in different diagrams to refer to the same elements or additional instances of the same element. Also, although aspects and features may in some cases be described in individual figures, it will be appreciated that features from one figure or embodiment can be combined with features of another figure or embodiment even though the combination is not explicitly shown or explicitly described as a combination. As one of many examples, it is appreciated that aspects, according to the present disclosure, for implementing a capacitive force sensor may be combined with aspects for implementing a vibration and / or piezo-electric sensor, soSTFD.466PCT (S21-329) 7 as to form a force sensor designed to sense pressure (e.g., vertical) forces as well as forces associated with a vibration and / or piezo-electric sensor.

[0031] Exemplary' aspects of the present disclosure are related to methods, materials and semiconductor structures for implementing a force-sensing apparatus (e.g., synthetic skin), with the apparatus comprising an electrode layer and a plurality of deformation-recoverable microstructures in a dielectric region adjacent the electrode layer. In various more specific examples, the deformation-recoverable microstructures are randomly configured (e.g., in terms of morphology and / or spatial distribution) and, as in a capacitive-ty pe sensor, the dielectric region may include a dielectric layer between a pair of electrode layers and with the dielectric layer and / or at least one of the electrode layers having such deformation- recoverable microstructures integrated into a surface and extending in a direction to sense forces applied towards or against the force-sensing apparatus.

[0032] In more specific contexts, exemplary aspects of the present disclosure are directed to example approaches to fabricate soft and stretchable microstructured electrodes and dielectrics with deformation-recovery attributes for force sensor applications. Such approaches (e.g., using computer-aided design and laser printing) rely on surface microstructures (“microstructures” encompassing sizes that are micro-sized and smaller such as nanostructures) that can be generated by rastering a laser beam (e.g.. either IR laser or other wavelength) to produce, via at least pseudo-randomly (if not entirely random), a configuration of materially -based structures on and / or integrated into the surfaces of various substrates. As examples, such materially-based structures may be configured into arbitrary- shapes, linewidths, sizes, and / or distributed patterns, for example, with at least one or more of these attributes being formed and / or configured via a degree of arbitrary selection or randomness. Physical properties of these laser-generated structures (e.g., height, size, periodicity7, and randomness) could be tuned by changing laser writing parameters (e.g., to change the morphology of such structures, the degree of random differentiation, and / or the degree of spacings between such structures (aka periodicities)). In addition, such approaches may involve preparing soft and stretchable microstructured electrodes and dielectrics from laser-manufactured structures and, as in certain examples, may involve designs incorporating microstructured electrodes and / or dielectrics for both standalone and multiplexed force sensing applications. In specific implementations such applications may include: (1) capacitive pressure sensors featuring different structural configurations for tunable sensing performance; (2) piezoresistive pressure and shear sensors featuring different microstructures for tunable sensing performance; (3) vibration sensors for dynamic vibration detection; (4)STFD.466PCT (S21-329) 8 dynamic tactile perception systems for robotic applications; (5) force-mapping devices for medical diagnostic and therapeutical applications; (6) wearable devices and sensors for physical and physiological monitoring; and (7) force-sensing devices for interactive humanmachines interfaces.

[0033] Accordingly, in the following description various specific details are set forth to describe specific examples presented herein. It should be apparent to one skilled in the art, however, that one or more other examples and / or variations of these examples may be practiced without all the specific details given below. In other instances, well-known features have not been described in detail so as not to obscure the description of the examples herein. For ease of illustration, the same reference numerals may be used in different diagrams to refer to the same elements or additional instances of the same element. Also, although aspects and features may in some cases be described in individual figures, it will be appreciated that features from one figure or embodiment can be combined with features of another figure or embodiment even though the combination is not explicitly shown or explicitly described as a combination. Further (and especially in connection with the following discussion and the discussion presented in the Appendices), unless otherwise indicated ranges (of any, and all metrics) are merely exemplary of ranges and use of “approximate” or “approximately” refers to a range from 10-to-20 percent and. in the context of comparison to an improvement over a previously-reported effort, by a degree of improvement of at least 20 percent.

[0034] Consistent with the above aspects, such a manufactured device or method of such manufacture may involve aspects presented and claimed in U.S. Provisional Application Serial No. 63 / 702,585 filed on October 2, 2024 (STFD.466P1 / S21-329) with Appendices A- C, to which priority is claimed. To the extent permitted, such subject matter is incorporated by reference in its entirety generally and to the extent that further aspects and examples (such as experimental and / more-detailed embodiments) may be useful to supplement and / or clarify.

[0035] FIG. 1 A is a perspective view of an exemplary type of sensor embodiment, and is used to represent different exemplary types of sensor embodiments, according to the present disclosure. In each of these types of sensor embodiments, common aspects include, for example: a dielectric region; an electrode layer including a dielectric-facing side that faces the dielectric region; and a plurality of deformation-recoverable microstructures, between or integrated the layers and extending into the dielectric region, that are arbitrarily, or at least pseudo-randomly, configured in terms of at least one of morphology and spatial distribution. The deformation-recoverable microstructures are cooperatively arranged with the electrodeSTFD.466PCT (S21-329) 9 layer to respond to pressure applied against or towards the apparatus by becoming compressed into a compressed state and, upon a release of the pressure applied against or towards the apparatus, by recovering into an uncompressed (e.g., pre-force) state.

[0036] Among such different exemplary types represented by FIG. 1A, a one specific type corresponds to a capacitive force sensor in which, as depicted in FIG. 1 A. a multilayered structure includes: a dielectric layer including an electrode-facing side (e g., middle layer of FIG. 1A); a first electrode layer (upper or lower layer of FIG. 1 A) including a dielectricfacing side that is secured to or against electrode-facing side of the dielectric layer; a second electrode layer (lower or upper of layer of FIG. 1A) including a dielectric-facing side that is secured to or against electrode-facing side of the dielectric layer; and a plurality of deformation-recoverable microstructures (between middle and upper of layers of FIG. 1A) that may be integrated into at least one of the electrode-facing side and at least one of the dielectric-facing sides and that are at least pseudo-randomly configured in terms of at least one of morphology and spatial distribution.

[0037] A second specific type (generally represented with reference to FIG. 1 A) is a multi-electrode force sensor designed as a capacitive sensor, or designed as a vibration and / or piezo-electric sensor. In this design type, the multilayered structured includes: opposing electrode layers (e.g., upper and lower electrode layers as in FIG. 1A); a dielectric region between the electrode layers (providing space(s)) separating flat portions of the inner-facing surfaces of the electrode layers; and a plurality of arbitrarily or at least pseudo-randomly configured deformation-recoverable microstructures that are integrated into (or on) one or more of the inner surfaces of the multiple layers of the multi-electrode force sensor and that extend from such surface(s) to partially the dielectric region. In this manner, the space(s) and the deformation-recoverable microstructures separate the flat portions of the inner-facing surfaces. Depending on the design requirements, the space(s)) separating the flat portions of the inner-facing surfaces of the electrode layers the dielectric region may or may not include a solid dielectric material layer. For example, without a solid dielectric material layer, the dielectric region may be defined by ambient oxygen (or a gas) that surrounds the deformation-recoverable microstructures. Various examples in this regard are discussed further supra (e.g., in connection with FIGs. 10A-10C and FIGs. 11A-11C).

[0038] Another specific t pe (also generally represented with reference to FIG. 1A) is a single-electrode force sensor designed as a capacitive sensor, or designed as a vibration and / or piezo-electric sensor. In this design type, the multilayered structured includes: only one electrode layer (e.g., upper electrode layer in FIG. 1 A); a dielectric region adjacent theSTFD.466PCT (S21-329) 10 single electrode layer; and a plurality of arbitrarily or at least pseudo-randomly configured deformation-recoverable microstructures that are integrated into (or on) a surface of the electrode layer and extend from the surface of the electrode layer towards the dielectric region.

[0039] As shown in the form of a glove to the left of FIG. 1 A, each of these exemplary types of sensor embodiments can be implemented as an electronic- and / or synthetic-skin sensor embodiment. Alternatively, these exemplary types of sensor embodiments can also be implemented as electronic-patch and / or as small sections of synthetic-skin.

[0040] Also according to examples of the present disclosure. FIG. 2A is a set of exemplary structures (SI, S2 and S3), the latter two of which are example embodiments, according to the present disclosure, and FIGs. 2B, 2C. 2D, 2E, 2F, 2G and 2H are respective graphs showing attributes of these exemplary7force sensors that feature skin-like softness and can withstand various mechanical deformation such as bending, stretching, and twisting.

[0041] In experimental (and / or proof-of-concept) efforts associated with certain types of force sensors, the pressure sensors were constructed in a parallel-plate configuration, where a dielectric layer is sandwiched by a pair of electrodes. Different levels of microstructural engineering can be readily adjusted by incorporating microstructured electrodes and dielectrics prepared under varied laser powers. Consistent with such efforts and as part of a control study, a series of soft capacitive pressure sensors are fabricated with an increasing level of overall microstructuring, as shown via the three types (SI, S2 and S3) of multilayered structure of FIG. 2A.

[0042] For a non-microstructured type of design (SI type design at the left of FIG. 2A), the sensors showed only a small average increase in capacitance under a large pressure of approximately 560 kPa, with a low average sensitivity7. Such aspects are depicted, for example, by the lower group of plots (labeled SI) in FIG. 2B and left-most pair of bars in FIG. 2C. For the partially-microstructured designs consistent with the present disclosure (S2 type design, as in the middle group of FIG. 2B and sets of bars labeled S2 in FIG. 2C). the sensors exhibited much improved sensitivities, as the laser power used for electrode preparation increased. For fully -microstructured designs according to examples of the present disclosure (S3 type design), the sensors revealed the largest pressure-induced responses as also charted in FIGs. 2B and 2C, with high sensitivities on par with previously reported plastic capacitive sensors fabricated via photolithography -patterned micro-pyramidal dielectrics using a conventional non-arbitrary configuration. This improvement (e.g., as in S2 and more so in connection with S3) is believed to be due to a combined effect of improvedSTFD.466PCT (S21-329) 11 microstructural engineering within both electrodes and dielectrics, where soft elastic microstructures are more easily deformed due to a reduced degree of stiffness and due to increased free air volume in between the structures. As such, when compared to that of nonmicrostructured sensors, microstructured pressure sensors consistent with the present disclosure featured an average of more than a 140-fold increase in terms of low-pressure sensitivity and an average of more than a 38-fold increase in terms of high-pressure sensitivity. With such increased performance, such microstructured pressure sensors consistent with the present disclosure are capable of detecting small weights, as low as that of a single strand of hair (approximately 0.2 mg) as represented in FIG. 2D, as well as gentle dynamic stimuli such as hair poking. In addition, the soft sensors consistent with the present disclosure are highly reproducible across multiple independently fabricated devices of the same ty pes, in terms of their pressure response curves (FIG. 2E), and sensitivities (FIG. 2F). Taken collectively, these experimental efforts demonstrate the effectiveness and robustness of applying simple DiLW-assisted fabrication for high-performance soft capacitive pressure sensors with broad dynamic ranges and low limits of detection.(0043) To study the effects of microstructural engineering on the pressure-sensing performance of such examples of soft capacitive pressure sensors, seven different levels of device microstructural engineering were introduced to the sensors by incorporating various combinations of microstructured electrodes and dielectrics that were prepared under different laser powers from 15% to 50% (unless otherwise mentioned), as detailed in the below Table 1 for SI, S2 and S3 type designs.[0044 j Table 1:STFD.466PCT (S21-329) 12(0045 J The above-characterized sensors were named as E-X / D-Y’, where E-X’ denoted the percentage of laser power (X%) used to manufacture the electrode pairs and ‘D- Y’ denoted the percentage of laser power (Y%) used to manufacture the dielectric molds. The speed and resolution during the laser writing process were maintained constant at 30% and 600 dpi, and all the sensors were fabricated with the same procedure with the same device geometries (i.e., the same sensing and electrical lead areas as defined above).

[0046] In certain specific examples according to the present disclosure, the electrodes (e.g., as laser-induced cavitation (LIC) / SEBS material) are intrinsically microstructured on the surface, and a combination of 5-nm chromium (Cr) and 50-nm gold (Au) are used as flat planar electrodes (E-0) for the non-rmcrostructured sensor design (i.e., SI type). The Cr / Au electrodes are sequentially deposited at a rate of 0.1 nm / s and 1 nm / s onto a flexible support substrate made of polyethylene terephthalate (PET, McMaster Carr, 127 pm thick) using a thermal evaporator (e.g.. via Thermionics Laboratory).

[0047] In certain example specific embodiments of this type, such processing produces thin LIC / SEBS electrodes with skin-like softness approximately 6-8 MPa) and stretchability (>400% strain), as well as excellent pressure-insensitive electrical conductivity (approximately 700-1,400 Q / sq), making them suitable for capacitive pressure-sensing electrodes, and yielding high-design flexibility’ with DiLW, soft LIC / SEBS electrodes can be manufactured into arbitrary patterns from simple geometries to complex patterns. In some of these specific embodiments, microstructured surfaces of the soft LIC / SEBS electrodes resulted in having a typical peak-to-valley distance in a range from 20 to 40 pm, and / or with the surface morphology of the LIC / SEBS electrodes being controllable by adjusting the laser power, which can transition from sparsely distributed microstructures with relatively flat profiles under small powers into denser and rougher microstructures with much steeper profiles under large powers. This can be especially useful in digital laser writing for manufacturing soft elastic electrodes with tunable levels of microstructuring, which can be important in some examples and embodiments for tailoring the performance of capacitive pressure sensors (e.g., sensitivity’, hysteresis, and response). In this regard, it is noted that methods in accordance with certain examples of the present disclosure may provide significant advancements. These method include, for example: (1) photolithography to micropattern structures such as pyramids, ridges, and domes; (2) replicating pre-existing surface textures; (3) forming micropores using sacrificial agents; and (4) direct 3D printing). In connection with the present disclosure, such specific examples provide advancements as heretofore such methods either cannot be rapidly prototyped or cannot achieve highSTFD.466PCT (S21-329) 13 resolution for large-scale personalized e-skins; this follows as it has been significantly challenging to apply a single manufacturing approach for microstructural engineering of soft capacitive pressure sensor components with highly customizable characteristics. This is of particular importance for understanding human-human and human-robot interactions, where personalized e-skin may be required for individuals or meet the demands of changing requirements.

[0048] In comparison with soft SEBS, the rigid PET is a more reliable substrate for thin Au / Cr electrodes upon pressure and should offer better dynamic sensing performance due to the reduced viscoelasticity of PET. The flat dielectrics (i.e.. D-0) for the nonmicrostructured and partially microstructured sensor designs (i.e., SI and S2 types) were prepared by spin-coating 1 mL SEBS solution (Asahi Kasei Tuftec™ H- 1062, 150 mg / mL in toluene) onto a flat square-shaped glass substrate (1 x1 inch2) at a rate of 3000 rpm for 30 seconds with an acceleration of 3000 rpm / s, which were heated at 120 °C for 1 minute to remove any residual solvent and then easily delaminated from the glass substrate with the assistance of an adhesive-tape frame. In all cases, multiple independent devices were fabricated for each control group and successfully tested multiple times for each device in the subsequent benchtop sensor characterization experiments.

[0049] These experimental efforts also investigated the hysteresis of DiLW- manufactured soft capacitive pressure sensors. The hysteresis is defined as the ratio of a sensor’s capacitance difference (AC7) at a given pressure during a consecutive loading and unloading cycle to the full-scale capacitance change (ACfi). The fully-microstructured sensors (S3: E-50 / D-50) showed a much-reduced average hysteresis of only approximately 5.6% and much lower standard deviations across multiple independent devices compared to the non-microstructured sensors consistent with the SI type design (see FIG. 2G). The improvement with the fully microstructured S3 type sensors can be attributed to: the reduced interfacial adhesion due to increased surface roughness; and the abundance of free air volume within the micro- / nanostructures, which effectively decreases the relaxation time of the compressed structures and thus promote faster recovery upon pressure release. Notably, the low hysteresis of the S3 type sensors is comparable to commercial plastic (but rigid) pressure sensors (e.g., Tekscan FlexiForce WB201 :4.5% of full scale). Furthermore, both the SI and S3 sensor types show fast responses upon weight loading due to the instantaneous deformation of the sensors’ internal structures, and negligible difference was observed (see FIG. 2H at left). However, upon unloading, the S3 type sensors showed much faster recovery within a few hundreds of milliseconds, while the S 1 Wpe sensors were not able to fullySTFD.466PCT (S21-329) 14 recover even after six seconds (see FIG. 2H at right). This difference was consistently observed under different loads and was in good agreement with previous results obtain in connection with efforts leading up to the present disclosure. Taken together, these experiments highlight the advantages of partially and fully microstructural engineering, e.g., enabled by versatile DiLW to enhance dynamic sensing performance. The long-term cyclic performance of such DiLW-manufactured soft capacitive pressure sensors appeared highly consistent with almost no drift or decay over a course of 9,000 consecutive cycles that lasted for over 36 hours. In addition, these experiments demonstrate that such example sensors exhibit small changes in both the maximum capacitance (e.g.. increased by approximately 2.32%) and the minimum capacitance (increased by approximately 5.39%) after 9,000 cycles, as well as negligible variations in the small-pressure sensitivity and low-hysteresis performance. Notably, the pressure-sensing profiles of the beginning 10 cycles matched well with the last 10 cycles, indicating the reliable mechanical and electrical functionalities of each such sensors’ constituent electrodes and dielectrics manufactured by DiLW. These results showcased the extraordinary cycling stability and structural robustness of such DiLW- manufactured soft capacitive pressure sensors for extended use.[00501 FIGs. 3A, 3B and 3C (Appx A) show exemplary engineering attributes consistent with certain embodiments, according to the present disclosure, that also stem from such experimental efforts. For example, such experimental efforts included fabrication of multiplexed sensor arrays using a single-round DiLW process to give various designed levels of pressure-sensing performance by programming laser parameters, combined with sensor location, size, pattern, and routing for electrical interconnects.[0051 J As exemplified in FIG. 3 A, distributed sensing performance can be encoded within a single sensor array, with the pixels in the same rows (despite the presence of different geometrical shapes) exhibiting relatively consistent pressure-induced responses. More specifically, the left portion of FIG. 3 A shows that distributed sensor engineering according to the present disclosure can be enabled by a single round of DiLW process, and as such a single sensor array can be encoded with various shapes (e.g., circle, triangle, square, and / or star) along each row and with varied levels of microstructuring (e.g., E-20 / D-0, E- 20 / D-20, and E-40 / D-40) along each column). The right portion of FIG. 3 A is an image of a 3x4 soft capacitive pressure sensor array with distributed sensor engineering.

[0052] Still referring to the array of FIG. 3A, the pixels in the same columns (despite the presence of same geometrical shapes) displayed distinct responses adjustable by their microstructuring levels. FIG. 3B is a 3D bar plot of small-pressure sensitivities (0-10 kPa) ofSTFD.466PCT (S21-329) 15 individual pixels within the 3x4 sensor arrays. FIG. 3C is a 3D bar plot of the relative capacitance change ratio (AC / CO) of individual pixels within the same arrays at an applied pressure of 150 kPa. The statistics in FIG. 3B and in FIG. 3C were calculated from three independent devices.

[0053] FIGs. 3D and 3E show certain example embodiments of the present disclosure for covering different exemplar}' areas to be sensed. For example, such efforts were used to construct soft multiplexed sensor arrays in crossbar formats with unmatched design flexibility-. This is shown in FIG. 3D, which shows a distribution of soft multiplexed pressure sensor arrays across a human body, featuring a broad manufacturable size range. The illustrated sensor arrays are constructed in cross-bar configurations to reduce wires and can read force-induced responses using a custom-built readout circuit (see FIG. 3D insets).

[0054] As shown in FIG. 3E, a miniaturized 8x8 sensor array is placed on the fingertip. These multiplexed sensors in the example of FIG. 3E can be implemented to feature an ultrahigh density of approximately 5,057 pixels per cm2in an 8x8 array, with each pixel sized at approximately 90x90 um2 and a spacing of approximately 30 pm between adjacent pixels. Notably, the density' of this miniaturized sensor array is among the highest values reported in the literature and is 20 times higher than that of biological mechanoreceptors in human fingertips (approximately 240 units / cm2). In principle and consistent with such exemplary aspects, the manufacturable spatial resolution can be further increased by either applying shadow' masks or using a shorter wavelength ultraviolet laser source for electrode carbonization. Remarkably, from these experimental efforts it w as discovered that all 64 individual sensing pixels in the miniaturized array exhibited uniform pressure-sensing responses, including their low-pressure sensitivities, with little hysteresis over multiple consecutive cycles. Enabled by an inexpensive custom-built readout circuit, these specific examples of sensor arrays were able to clearly recognize 3D patterns, such as reading the entire alphabet, and visualize dynamic interactions in real-time, such as single touch, multitouch, and rolling motions, while maintaining their functionalities when conformally integrated onto a curvilinear surface. In addition, such soft sensor arrays may' be scaled up into w earable configurations with various shapes and coverage sizes, as shown by an arm sleeve, a headband, and a shoe insole, which can be comfortably fit on various body regions. Moreover, advanced sensor designs can be easily prototyped using DiLW, as shown by a 288-pixel spirally coiled sensor array that can be extended to over 25 meters in length and a soft expandable metastructure-based network with 83 embedded sensors at joints.STFD.466PCT (S21-329) 16

[0055] These experimental efforts also included demonstration of full-hand tactile perception. To this end, DiLW was used for customizable large-scale pressure-sensing electronic skin (DigiSkin) to achieve full-hand tactile perception for human wearers and humanoid robots. To date, full-hand sensor integration has been challenging due to the lack of accessible manufacturing processes, and which processes largely rely on manually- assembling (often commercial) sensors into wearable gloves. These sensorized gloves usually require use of rigid active components with low customizability and have limited performance and sensing ranges, low spatial resolution, and restricted to 2D (two- dimensional) planar sensing. A first example ensuing from these experimental efforts was demonstrated a full-hand wearable tactile electronic skin (DigiSkin-H) for human wearers to record interactions with surroundings. It is soft and stretchable and has a low profile with a total thickness of <400 pm, featuring 256 pressure-sensing pixels divided into 15 sub-regions (i.e., 14 finger phalanges and 1 palm) with a higher coverage (>56%) of sensors on the fingers. Multiple design variants of DigiSkin-H can be readily manufactured in a single batch with variable sensor sizes, distributions, densities, and local microstructuring characteristics of individual sensing pixels, allowing enormous design flexibility for personalization and application scenarios.

[0056] According to certain specific examples of the present disclosure, a typical automated process for fabrication of an adult-size DigiSkin-H was demonstrated as taking only about 15 minutes (at 200 dpi). The soft and stretchable DigiSkin-H can be comfortably attached to a human hand or a glove without hindering the wearer’s mobility and their own tactile experience. The individual pixels were 100% functional and showed uniform pressure- induced responses. Surprisingly, the DigiSkin-H allowed wearers to record large-scale tactile interactions during object grasps with negligible latency, capturing rich tactile information (e.g., contact location, pressure distribution, and relative magnitude) for various objects over sequences of actions. Based on the time-dependent tactile information collected from a library of 42 object classes (average of approximately 12.838 frames per class), an advanced machine learning model was constructed based on long short-term memory (LSTM) networks for human grasp analysis. Since DigiSkin-H does not change the wearer’s natural pattern of interactions with objects, it provides unprecedented opportunity to record and understand human interactions with surroundings. This will provide valuable information for both robotic skin and control algorithm design. For example, compared to fewer-finger configurations (where only parts of the full-hand tactile data were used), full-hand sensor design showed the highest average object recognition accuracy of approximately 92.37%, asSTFD.466PCT (S21-329) 17 shown by the confusion matrix, representing a significant increase from approximately 88.31% (5-finger design), approximately 76.58% (2-finger design), and approximately 62.85% (thumb-only design). This improvement was consistently observed across individual object classes. These results confirmed the necessity of acquiring large-scale tactile information from multiple fingers for improved grasp recognition performance and demonstrated the clear advantage of biomimetic full-hand sensor designs (i.e., five fingers with a palm) over two-finger grippers that are most commonly used in existing robots. In a second example, a bioinspired modular electronic skin for full sensory7coverage was successfully demonstrated on a humanoid robotic hand (DigiSkin-R). The bioinspired design features: (1) high-resolution sensing on the fingertips, (2) 3D spatial sensing on the phalangeal sides, and (3) large-area sensing on the palm and back regions. Based on the 3D geometry of the hand, separate patches of soft sensor arrays were designed to fit onto the irregularly -shaped hand. Such a modular design features a low maintenance burden as each patch can be individually replaced in case of failure or needs for performance tailoring. In other examples stemming from such efforts, a humanoid robotic hand was outfitted with DigiSkin-R features having as many as 2,496 functional pixels. By developing streamlined 3D electrical interconnections, 3D sensor integration was achieved with up to 270° spatial coverage around the finger phalanges. This fully sensorized robotic hand fingertip was capable of accurately recognizing sub-millimeter small features with linewidths as small as 500 pm. Additionally, extending tactile sensation into 3D space on the phalangeal sides provided the robotic hand with valuable environmental awareness during tool handling and tactile exploration, as exemplified by (1) the tracking of the rotation of a spatula held in between two fingers and (2) the differentiation of object softness through gentle finger pressing. Furthermore, the large-area palm region served as a dynamic interface for sensing social interactions and manipulative commands between the robotic hand and humans (or another robot), which has not been achieved previously in humanoid robotics. Given the high sensor counts, the robotic-type hand was capable of not only detecting various types of gestures (e.g., pinch, poke, knock, slap, pat, rub, twist, sweep, high five, shake hand) with a high average classification accuracy of approximately 97%, which may convey specific emotional and psychosocial cues, but also transforming its surface into an interactive interface for information input (e.g., a pressure-sensitive drawing pad with a gesture- controlled color dial).

[0057] Also consistent with such experimental efforts and certain example embodiments of the present disclosure, such experimental efforts produced images showing surfaceSTFD.466PCT (S21-329) 18 morphology of different replicated microstructured PDMS molds, with different surface- related attributes such as roughness and height aspects, relative to a reference surface of microstructured PDMS molds and as implemented at power levels respectively corresponding to 15%, 25%, 35% and 50%. In certain of these examples, the microstructured PDMS molds were templated using LIC / SEBS electrodes prepared under such varied laser powers (i.e., 15%, 25%, 35%, and 50%) and were subsequently used for fabrication of microstructured SEBS dielectrics. These surface-related attributes respectively correspond to sets of representative surface height profiles over a surface distance of about 250 microns. For the 15% laser power (E-15),the height profile was in a range from -5 microns to +5 microns. For the 25% laser power (E-25),the height profile was in a range from -3 microns to +11 microns. For the 35% laser power (E-35),the height profile was in a range from -5 microns to +14 microns. For the 50% laser power (E-50), the height profile was in a range from -10 microns to +20 microns. Accordingly, quantitative analysis of the microstructured PDMS molds according to such examples of the present disclosure shows that the surface morphological characteristics are a function of laser power. In certain instances, these experimental efforts employ a template-molding process to fabricate soft and deformable microstructured dielectrics (e.g., made of SEBS) by replicating the surfaces of LIC / SEBS electrodes, with resulting dielectric regions appearing optically opaque because of diffusive light scattering that occurs at irregular interfaces, and with the dielectrics’ surface microstructural characteristics being tunable and resembling their corresponding original LIC / SEBS templates, thereby indicating effective structural replication, and with the highly deformable soft microstructured dielectrics being high customizability’ (e.g., size, pattern, sensitivity, and sensing range) without the need for more expensive and slower throughput photolithography method.

[0058] FIGs. 4A-4D show exemplary' attributes or aspects, consistent with certain embodiments of the present disclosure, of deformation-recoverable microstructures, each showing a top-down view. In each of FIGs. 4A-4D. the darker areas between the depicted microstructures are regions not structured as such, for example, flat regions. FIG. 4A shows examples of different shapes of the formed structures (microstructured electrodes and / or dielectrics) in the forms of a four-sided shape (e.g., a square or rectangle). FIG. 4B shows examples of different linewidths (e.g., as electrodes and / or interconnecting structures) in terms of cross-sectional area, width and / or thickness. FIG. 4C shows examples of different sizes of such structures in terms of area and / or volume. FIG. 4D shows examples of different types of patterns of the formed structures in terms of area and / or volume.STFD.466PCT (S21-329) 19|(X)59 ] FIGs. 5A-5B illustrate aspects of exemplary deformation-recoverable microstructures, consistent with certain embodiments of the present disclosure. FIG. 5A shows a side view of exemplary deformation-recoverable microstructures, consistent with certain embodiments of the present disclosure, featuring differently sized microstructures, in terms of height, volume, shape and / or cross-sectional area, including such microstructures that are: large, medium, small and absent (e.g., flat).

[0060] FIG. 5B shows a top-down view of different arrangements (in regions depicted as i, ii, iii, and iv) of exemplary deformation-recoverable microstructures, with each such region corresponding to different types of patterned structures in the electrode and / or dielectric material. Such regions can be arranged in ordered fashion or random (e.g., pseudo-random or completely random) depending on design goals or requirements.

[0061] FIGs. 6A-6D show exemplary fabrication aspects and related attributes, consistent with certain embodiments of the present disclosure, of deformation-recoverable microstructures as fabricated in electrode material. As depicted, this may be accomplished by converting polyimide (or a polymer containing film) into electrically conductive microstructured material (e.g., carbon (LIC)) through direct laser writing by way of rastering (or raster scanning) a substrate as in FIG. 6A. This step is followed by transferring the LIC onto and / or into an elastomer (e.g., SEBS or PDMS) as in FIG. 6B. The next step, at FIG. 6C, involves casting such an elastomer (SEBS) solution over the formed (e.g., LIC) microstructured material. Finally at FIG. 6D, delamination is effected for removal of the layer including the SEBS solution shown in FIG. 6C. In a more specific example process, an uncured thermoplastic elastomer solution (e g., made of styrene-ethylene-butylene-styrene (SEBS)) is dropcasted onto the L1C / P1 substrate, which is then left overnight or sufficiently long to completely (or almost completely) remove any residual solvent. For example, the cured SEBS elastomer may be delaminated from the PI substrate by directly delaminating the cured SEBS elastomer from the PI substrate with the conductive LIC networks fully encapsulated and transferred to the SEBS matrix.

[0062] FIGs. 7A-7F show exemplary fabrication aspects and related attributes, consistent with certain embodiments of the present disclosure, of deformation-recoverable microstructures in dielectric material. This approach is to generate surface microstructures on substrates (e.g., suitable substrates including glass, acrylic, cellulose, wood, and many other laser-compatible plastics) through direct laser writing and then replicate the microstructures using a molding process. The steps shown in FIGs. 7A-7B correspond to steps shown in FIGs. 6A-6B. FIG. 7C shows a PDMS mixture in uncured form over the (laser-induced)STFD.466PCT (S21-329) 20 deformation-recoverable microstructured material (aka L1M material). As in FIG. 6D, the step of FIG. 7D involves delamination to isolate the cured form of the PDMS mixture for providing a mold. FIG. 7E shows casting of the SEBS solution into the PDMS-based mold. Finally, FIG. 7F shows the mold being separated to provide the SEBS-based dielectric material with the deformation-recoverable microstructures on one of its sides. For a SEBS- based dielectric material layer with two opposing sides having such deformation-recoverable microstructures, this process can be repeated for a pair of SEBS-based dielectric material having the flat side of one such material each being bonded to the flat side of the other material.

[0063] In connection with the above discussion of FIGs. 6A-6D and Figs. 7A-7F, more specific experimental embodiments and efforts have revealed a number of other important aspects and discoveries. For example, in connection with the present disclosure it has been discovered that randomly distributed (e.g., pseudo-randomly) microstructures of electrically conductive laser-induced carbon (LIC) with highly porous small structures formed in between the randomly-configured microstructures can be advantageous in reducing adhesion so that the sensor can rapidly return to original shape, thereby enhancing low hysteresis. Accounting for the microstructures and highly porous small structures between the microstructures, measuring along a plane of the surface, the peak-to-valley distances vary in one or more ranges on the order of a nanometer, a micron and in some instances as large as a millimeter. In some instances due to the randomness of microstructures’ morphology7, the peak-to-valley distances can vary7in a wide range, such as w ith the vertical distance range being set in a range from a nanometer to as high as a micron or on the order of a millimeter. Such aspects can be readily generated on the surface of a bare polyimide (PI) substrate (e.g., under the irradiation of an infrared CO2 laser) and used in force sensors such as exemplified herein according to the present disclosure. As an example, such aspects can be used with LIC for producing a microstructured dielectric enable designs with tunable responses and sensitivities.

[0064] FIGs. 8A-8D show exemplary attributes, consistent w ith certain embodiments of the present disclosure, of a multiplexed type of capacitive pressure sensor including deformation-recoverable microstructures in electrode material and / or dielectric material. FIGs. 8A and 8B respectively show a single sensor (or individual sensing pixel) and a multiplexed sensor array, the latter including a grid of individual sensing pixels. The grid is defined by row s and columns of electrodes with a dielectric material, as in each of FIGs. 8C and 8D, separating an area where each row7intersects with a column. At each intersection, theSTFD.466PCT (S21-329) 21 dielectric-facing side of one, or both, of the electrodes is microstructured as exemplified hereinabove.

[0065] One or both sides of the dielectric material is also microstructured as exemplified hereinabove, so that at each intersection the microstructures of the dielectric material can respond to a force (e.g., vertical and / or lateral) by engaging with the electrode microstructures that face the dielectric material. As depicted in FIG. 8C at the pixel of each grid intersection, without such a force (or pressure) the sensor manifests a low capacitance due to a relatively large separation distance between electrodes (e.g., with no engagement between the oppositely-facing microstructures). With pressure, engagement between the oppositely-facing microstructures causes the microstructures to deform, thereby resulting in reduced electrode separation and a corresponding increased (relatively high) capacitance. Laser-manufacturing the microstructures into the dielectrics and / or electrode(s) facilitates optimal pressure-responsive deformation and corresponding low-pressure sensitivity.

[0066] The pixel depicted in each of FIGs. 8C and 8D also exemplify that this forcecausing change in capacitance does not require that microstructures be on opposite-facing sides (e.g., for microstructure-to-microstructure engagement) in order for the pixel to respond to such a force. For example and as shown in FIGs. 8C and 8D, the engagement region between the lower electrode and the dielectric has only one set of microstructures. While such microstructures are shown in the example of FIGs. 8C and 8D as extending orthogonal from the material of the lower electrode upwardly to the dielectric, this arrangement can be altered (e.g., such microstructures can extend upwardly and / or downwardly from any of inner-facing surfaces of the dielectric / electrode material).

[0067] FIGs. 9A-9C illustrate further variations of such capacitive pressure sensors, also according to the present disclosure, each with a different configuration of deformation- recoverable microstructures in the electrode material and / or the dielectric material. As in FIG. 9A and as an alternative to the example of FIGs. 8C and 8D, the dielectric layer can be implemented as a plurality of immediately-adjacent dielectric-layer sections, with microstructures extending in the same direction for alignment with the force (as in FIG. 8D). Such dielectric-layer sections may be secured using a low-adhesion interfacial material (depicted by the line(s) delineating the edge of the surface(s)) where the dielectric-layer sections meet, and / or are secured by the same type of dielectric material (not shown) on the (left and right) side edges of the dielectric-layer sections. As noted above, the porousness of the surface areas between the microstructures facilitates such low-adhesion and aids in the low' hysteresis.STFD.466PCT (S21-329) 2210068 ] In each of FIG. 8C and FIGs. 9 A, 9B and 9C, the side-view depictions show an optional spacing (or optional gap) that defines separation, along a plane parallel to the surfaces and while there is zero pressure on the electrodes, between the tips of the inner- facing deformation-recoverable microstructures, and between the tips of each set of deformation-recoverable microstructures and the flat-like surfaces. In various examples using such a gap, in the non-zero state the gap between inner facing tips of oppositely-facing microstructures is an average distance within vertical distance range, which can be selected (e.g., as a function of attributes such as low-adhesion, low hysteresis and, more generally, recovery timing) to be in a range on the order of a nanometer, a micron to a millimeter. In some instances in which the heights of the microstructures are arbitrarily varied in a wide range, the vertical distance range can be set to be in a range from a nanometer to as high as a micron or on the order of a millimeter. In response to a pressure being applied towards or against the electrodes, the zero-pressure state of engagement changes to a non-zero pressure state wherein the engagement causes compression at the tips of each involved set of deformation-recoverable microstructures. Highly-flexible sidewalls (not shown in FIGs. 8C and 8D) on left and right sides of the depicted multilayered structures may be used to set the initial distance corresponding to the non-zero-pressure state. While each of FIG. 8C and FIGs. 9A, 9B and 9C depicting a non-zero-pressure state (with the optional separation), the transition to the non-zero-pressure state is shown in FIG. 8D, where the vertical force applied to the top of the upper electrode causes compression betw een the engaged microstructure tips between the upper electrode and the dielectric layers, and between the engaged microstructure tips of between the lower electrode and underside (flat) surface of the dielectric layer. Similarly, such a separation gap may be used in example embodiments which do not include a dielectric material layer (between the electrodes and / or the dielectric region), whether or not a capacitive-type force sensor; as examples, the multilayered designs in FIGs. 10A-10C and 11A-11C may be modified to include such a separation gap.

[0069] FIG. 9B shows yet another alternative example including immediately-adjacent dielectric-layer sections, each with microstructures extending in opposite directions and tow ards oppositely-facing electrodes. The flat (non-microstructured) sides of the dielectriclayer sections may be bonded together, for example, by using adhesion interfacial material along at least one of the flat surfaces where the dielectric-layer sections meet, and / or secured by the same type of dielectric material (not shown) on the (left and right) side edges of the dielectric-layer sections.STFD.466PCT (S21-329) 23{0070] FIG. 9C shows yet a third alternative example also including immediately - adjacent dielectric-layer sections, each with microstructures extending in opposite directions but with the microstructures directed inwardly and towards each other. The dielectric-layer sections may be bonded together, for example, by using low-adhesion interfacial material along at least one of the microstructured surfaces where the dielectric-layer sections meet, and / or secured by the same type of dielectric material (not shown) on the (left and right) side edges of the dielectric-layer sections.[007 I] As yet another alternative (not shown in combination), each of the immediately - adjacent dielectric-layer sections can have a microstructured surface on each side. For example, the multilayered dielectric of FIG. 9B can be replicated so as to be stacked between the upper and lower electrodes.

[0072] While many of the above example embodiments depict capacitive-type pressure sensors, FIGs. 10A-10C show exemplary attributes, consistent with certain embodiments of the present disclosure, of piezoresistive-type pressure sensors. Each of these depicted piezoresistive-type pressure sensors includes one of different configurations of deformation- recoverable microstructures in electrode material. Generally (and unless explicitly noted), related aspects of the piezoresistive-type pressure sensors of FIG. 10A-10C correspond to the capacitive-type pressure sensors of FIGs. 8A-8D. As examples, such related aspects correspond to the configurations of: the array; the pixels defined by the grid; the electrodes on the upper and lower sides of a dielectric region wherein the dielectric material of the examples in FIGs. 8A-8D may reside; and material (if any) that may be used on the left and right sides of the depicted structures to secure or enclose the dielectric region.

[0073] Consistent with the depictions of FIGs. 10A-10C, configuration examples of the dielectric region (between the electrodes in the piezoresistive-type pressure sensor): may be void of material such as occupied by a gas such as oxygen; may include a highly-flexible thin material (e.g., a non-binding polymer) that is sufficiently thin and non-binding to minimize interference while the microstructures of the electrodes engage while under pressure; may be implemented by using a highly -fluidic gel that is sufficiently thin and fluidic to minimize such interference while the microstructures engage under pressure; and may be implemented as a combination of the above two configurations (including in the dielectric region a highly- flexible thin material, a fluidic gel, and / or partially void). Such a thin material in the dielectric region is depicted as an option, using dashed lines between the inner-facing surfaces of the electrodes shown on the left of FIG. 10C.STFD.466PCT (S21-329) 2410074] As noted above, the microstructures of the electrodes are configured to engage while under pressure. Without pressure, the sensor will have a relatively -high resistance, due to a low number of pathways for electron conduction. With pressure, the piezoresisti ve-type pressure sensor manifests a relatively-low resistance, which is due to increased electrontransfer pathways and improved electrode contacts upon deformation.

[0075] FIGs. 11 A-l 1C show examples of different feature-size attributes, consistent with certain embodiments of the present disclosure, which may be used for piezoresistive-type pressure sensor such as depicted in FIGs. 10A-10C. FIG. 11A shows relatively-large-sized microstructures, FIG. 11B shows relatively-medium-sized microstructures, and FIG. 11C shows relatively-small-sized microstructures. One or a combination of such different sized microstructures may be integrated into one or both electrodes for fine tuning of the piezoresistive pressure sensors’ sensing performance (e.g., gauge factor, response, sensitivity', hysteresis, and / or detection limit).

[0076] The type of structures shown in FIGs. 10A-10C and FIGs. 11 A-l 1C may be used to detect pressure forces (e.g., downw ardly directed), shear forces (e.g., directed laterally along a plane aligned with the elongated layers), and vibration-type forces (e.g., in one or more such directions). One or more of these types of sensing is facilitated by if the microstructures and / or electrodes being patterned to have alignment along a certain direction or multiple electrode arrays are used to provide temporal information.

[0077] Accordingly, exemplary' aspects of the present disclosure are directed to example approaches (e.g., involving a laser-assisted digital manufacturing) to enable soft and stretchable microstructured electrodes and dielectrics for force sensor applications. These application may include, as examples: (1) capacitive pressure sensors featunng different structural configurations for tunable sensing performance; (2) piezoresistive pressure and shear sensors featuring different microstructures for tunable sensing performance; and (3) vibration sensors for dynamic vibration detection.

[0078] Many different types of processes and force-sensing devices may be advantaged by aspects such as at least pseudo-randomly-configured microstructures and / or other aspects as addressed above. Exemplary applications for such processes and force-sensing devices, according to the present disclosure, include (without limitation) robotics and prosthetics, a wide range of electronically-enabled wearables such as synthetic skin, as well as others (including the related examples in the above-identified U.S. Provisional Application).

[0079] It is recognized and appreciated that as specific examples, the abovecharacterized figures and discussion are provided to help illustrate certain aspects (andSTFD.466PCT (S21-329) 25 advantages in some instances) which may be used in the manufacture of such structures and devices. These structures and devices include the exemplary structures and devices described in connection with each of the figures as well as other devices, as each such described embodiment has one or more related aspects which may be modified and / or combined with the other such devices and examples as described hereinabove may also be found in the Appendices of the above-referenced Provisional.

[0080] The skilled artisan would also recognize various terminology as used in the present disclosure by w ay of their context. As one example, the terms “comprising”, “including”, “having” and the like, are synonymous with each such term being open ended (as opposed to a term such as “composed only of’). As other examples, the Specification may describe and / or illustrates aspects useful for implementing the examples by way of various semiconductor materials / circuits which may be illustrated as or using terms such as layers, regions, and circuit-type depictions such as blocks, modules, device, system, unit, controller, etc. Such semiconductor and / or semiconductive materials (including portions of semiconductor structure) and circuit elements and / or related circuitry may be used together with other elements to exemplify how certain examples may be carried out in the form or structures, steps, functions, operations, activities, etc. It would also be appreciated that terms to exemplify orientation, such as upper / lower. left / right, top / bottom and above / below, may be used herein to refer to relative positions of elements as shown in the figures. It should be understood that the terminology is used for notational convenience only and that in actual use the disclosed structures may be oriented different from the orientation shown in the figures. Thus, the terms should not be construed in a limiting manner.

[0081] Based upon the above discussion and illustrations, those skilled in the art will readily recognize that various modifications and changes may be made to the various embodiments without strictly following the exemplary' embodiments and applications illustrated and described herein. For example, methods as exemplified in the Figures may involve steps carried out in various orders, with one or more aspects of the embodiments herein retained, or may involve fewer or more steps. Such modifications do not depart from the true spirit and scope of various aspects of the disclosure, including aspects set forth in the claims.

Claims

STFD.466PCT (S21-329) 26What is Claimed:

1. An apparatus comprising: a dielectric region; an electrode layer including a dielectric-facing side that faces the dielectric region; and a plurality of deformation-recoverable microstructures: extending into the dielectric region, being at least pseudo-randomly configured in terms of at least one of morphology and spatial distribution, and cooperatively arranged with the electrode layer to respond to pressure applied against or towards the apparatus by compressing into a compressed state and, upon a release of the pressure applied against or towards the apparatus, by recovering into an uncompressed state.

2. The apparatus of claim 1, wherein the deformation-recoverable microstructures are able to recover to a pre-deformed state, after being deformed in response to two or more deforming-force types from among: a force that causes the deformation-recoverable microstructures to bend; a force that causes the deformation-recoverable microstructures to stretch; a force that causes the deformation-recoverable microstructures to compress; and a force that causes the deformation-recoverable microstructures to twist.

3. The apparatus of claim 1, wherein the deformation-recoverable microstructures are able to recover to a pre-deformed state, after being deformed in response to each of the following deforming-force types from among: a force that causes the deformation- recoverable microstructures to bend; a force that causes the deformation-recoverable microstructures to stretch; a force that causes the deformation-recoverable microstructures to compress; and a force that causes the deformation-recoverable microstructures to twist.

4. The apparatus of claim 1, wherein the deformation-recoverable microstructures define porous nanostructures respectively in betw een the plurality of deformation-recoverable microstructures.STFD.466PCT (S21-329) 275. The apparatus of claim 1, further comprising: an electronic-skin material that includes: the dielectric layer, the electrode layer, and the plurality of deformation-recoverable microstructures; and a dielectric material layer in the dielectric region, wherein the plurality of deformation-recoverable microstructures are integrated into at least one of the dielectricfacing side of the electrode layer and an electrode-facing side of the dielectric material layer.

6. The apparatus of claim 1, comprising two electrode layers including the above-recited electrode layer as a first one of the two electrode layers and including a second one of the two electrode layers, wherein the dielectric region is between the two electrode layers.

7. The apparatus of claim 1, including a capacitive pressure sensor that includes a dielectric material layer in the dielectric region, the electrode layer, and the plurality of deformation-recoverable microstructures, wherein the plurality of deformation-recoverable microstructures are integrated with at least one of the dielectric material layer and the electrode layer.

8. The apparatus of claim 1, wherein the deformation-recoverable microstructures are predominantly composed of one of: electrically conductive laser-induced carbon; and styrene-ethylene-butylene-styrene (SEBS) elastomer.

9. The apparatus of claim 1, wherein each of the plurality of deformation-recoverable microstructures has an end that, before the pressure applied against or towards the apparatus, is prevented by a separation gap in the dielectric region from being in contact with any other material layer of the apparatus.

10. The apparatus of claim 1 , wherein the deformation-recoverable microstructures include a first set of deformation-recoverable microstructures and a second set of deformation-recoverable microstructures, each of the first set and the second set being compressible to change a volume associated with the dielectric region.STFD.466PCT (S21-329) 2811. The apparatus of claim 1, further including a dielectric material layer in the dielectric region, wherein the plurality of deformation-recoverable microstructures are integrated into at least one of the dielectric-facing side of the electrode layer and an electrode-facing side of the dielectric material layer.

12. The apparatus of claim 1 , wherein the deformation-recoverable microstructures include: electrically conductive laser-induced carbon and styrene-ethylene-butylene-styrene (SEBS) elastomer; a first set of deformation-recoverable microstructures; and a second set of deformation-recoverable microstructures that is integrated with and facing and the first set.

13. The apparatus of claim 1, further including a dielectric material layer in the dielectric region, wherein the at least one of the dielectric-facing side of the electrode layer and an electrode-facing side of the dielectric material layer are to provide an interfacial engagement between the at least one of the dielectric-facing side and the electrode-facing side, that facilitates recovery of the plurality of deformation-recoverable microstructures upon a release of pressure applied to or towards the plurality of deformation-recoverable microstructures.

14. The apparatus of claim 1, wherein the plurality of deformation-recoverable microstructures are at least pseudo-randomly configured in terms of a plurality of attributes from among sizes, shapes, height and periodicity, softness and stretchability. and are configured to sense at least one of vibration and shear forces.

15. The apparatus of claim 1, wherein the plurality of deformation-recoverable microstructures are at least pseudo-randomly configured in terms of size, height and periodicity.STFD.466PCT (S21-329) 2916. A method comprising: sensing a force applied by a tangible object relative to a sensor arrangement including at least one electrode layer with a dielectric-facing side that faces a dielectric region and including a plurality of deformation-recoverable microstructures being at least pseudo- randomly configured in terms of at least one of morphology and spatial distribution, wherein in response to the force being applied, via the plurality of deformation- recoverable microstructures, the plurality of deformation-recoverable microstructures deform and cause at least one of: a change in capacitance involving the dielectric region and the electrode layer, and a vibration due to lateral movement, relative to a plane along which the at least one electrode layer is arranged, of the plurality of deformation-recoverable microstructures.

17. The method of claim 16, wherein each of the plurality of deformation-recoverable microstructures has an end that, before the pressure applied against or towards the apparatus, is prevented by a separation gap in the dielectric region from being in contact with any other material layer of the apparatus, and in response to the pressure being applied against or towards the apparatus, the pressure overcomes separation gap thereby causing each of the ends to deform.

18. The method of claim 1 , wherein the plurality of deformation-recoverable microstructures are at least pseudo-randomly configured in terms of one or more of a plurality of attributes from among sizes, shapes, height and periodicity, softness and stretchability, to realize a specified degree of sensing performance; and to provide an interfacial engagement involving the dielectric-facing side, to facilitate recovery of the plurality of deformation-recoverable microstructures upon a release of pressure applied to or towards the plurality of deformation-recoverable microstructures, wherein the interfacial engagement is a function of surface roughness and free air volume within the plurality of deformation-recoverable microstructures.STFD.466PCT (S21-329) 3019. The method of claim 16. further including forming an electrode layer including a dielectric-facing side that is to face a dielectric region; and converting into a plurality of deformation-recoverable microstructures, via operation of a light beam generated by a laser, at least one of the dielectric-facing side of the electrode layer and an electrode-facing side of an electrode-facing side of a dielectric material layer residing in the dielectric region.

20. An apparatus comprising: a dielectric layer including an electrode-facing side; a first electrode layer including a dielectric-facing side that is secured to or against electrode-facing side of the dielectric layer; a second electrode layer including a dielectric-facing side that is secured to or against electrode-facing side of the dielectric layer; and a plurality of deformation-recoverable microstructures that are integrated into at least one of the electrode-facing side and at least one of the dielectric-facing sides and that are at least pseudo-randomly configured in terms of at least one of morphology and spatial distribution.

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