Transferring Microelectromechanical Devices to Breathable Fabric Carriers with Strain-Engineered Grippers

MRS Advances ◽  
2019 ◽  
Vol 4 (23) ◽  
pp. 1327-1334 ◽  
Author(s):  
Sushmita Challa ◽  
Canisha Ternival ◽  
Shafquatul Islam ◽  
Jasmin Beharic ◽  
Cindy Harnett
Keyword(s):  
Mechanical Strain ◽  
Soft Materials ◽  
Fine Tuning ◽  
Stretchable Electronics ◽  
Conductive Heat ◽  
Adhesion Forces ◽  
Fiber Networks ◽  
Microelectromechanical Devices ◽  
Carrier Materials ◽  
Breathable Fabric

ABSTRACTStretchable electronics fabrication generally relies on fine-tuning adhesion forces, putting some restrictions on what the carrier layer can be. In contrast to adhesion, mechanical tangling makes more kinds of carrier materials available. Antibacterial, conductive, heat-responsive and other functions can be brought in by fiber networks as long as they are compatible with the highly selective silicon etch process. Mechanical grippers can also bring electronic contacts from one side of a mesh to the other, which is difficult to do on continuous thin films of other soft materials like silicone or polyimide. Our solution uses mechanical strain to produce large arrays of redundant grippers from planar thin-film designs.

Mechanical Testing for Stretchable Electronics

2017 ◽  
Vol 139 (2) ◽  
Author(s):  
Steven A. Klein ◽  
Aleksandar Aleksov ◽  
Vijay Subramanian ◽  
Pramod Malatkar ◽  
Ravi Mahajan
Keyword(s):  
Mechanical Testing ◽  
Failure Modes ◽  
Mechanical Strain ◽  
Electrode Array ◽  
Expansion Method ◽  
Thin Metal Film ◽  
Thin Metal ◽  
Test Method ◽  
Stretchable Electronics ◽  
And Performance

Stretchable electronics have been a subject of increased research over the past decade (Lacour, S., et al., 2006, “Mechanisms of Reversible Stretchability of Thin Metal Films on Elastomeric Substrates,” Appl. Phys. Lett., 88(20), p. 204103; Lacour, S., et al., 2004, “Design and Performance of Thin Metal Film Interconnects for Skin-Like Electronic Circuits,” IEEE Electron Device Lett., 25(4), pp. 179–181; and Maghribi, M., et al., 2005, “Stretchable Micro-Electrode Array,” International IEEE-EMBS Conference on Microtechnologies in Medicine and Biology, pp. 80–83.). Although stretchable electronic devices are a relatively new area for the semiconductor/electronics industries, recent market research indicates that the market could be worth more than $900 million by 2023 (PR Newswire, 2015, “Stretchable Electronics Market Worth $911.37 Million by 2023,” PR Newswire, Albuquerque, NM.). This paper investigates mechanical testing methods designed to test the stretching capabilities of potential products across the electronics industry to help quantify and understand the mechanical integrity, response, and the reliability of these devices. Typically, the devices consist of stiff modules connected by stretchable traces (Loher, T., et al., 2006, “Stretchable Electronic Systems,” Electronics Packaging Technology Conference (EPTC '06), pp. 271–276.). They require electrical and mechanical connectivity between the modules to function. In some cases, these devices will be subject to biaxial and/or cyclic mechanical strain, especially for wearable applications. The ability to replicate these mechanical strains and understand their effect on the function of the devices is critical to meet performance, process, and reliability requirements. In this paper, methods for simulating biaxial and out-of-plane strains similar to what may occur in a wearable device on the human body are proposed. Electrical and/or optical monitoring (among other methods) can be used to determine cycles to failure depending on expected failure modes. Failure modes can include trace damage in stretchable regions, trace damage in functional component regions, or bulk stretchable material damage, among others. Three different methods of applying mechanical strain are described, including a stretchable air bladder method, membrane test method, and lateral expansion method.

scholarly journals Softer is Harder: What Differentiates Soft Robotics from Hard Robotics?

MRS Advances ◽  
2018 ◽  
Vol 3 (28) ◽  
pp. 1557-1568 ◽  
Author(s):  
Gursel ALICI
Keyword(s):  
Smart Materials ◽  
Control Algorithm ◽  
Soft Materials ◽  
Power Source ◽  
Stretchable Electronics ◽  
Power Requirement ◽  
Soft Robots ◽  
Hard Materials ◽  
Morphological Computation ◽  
Bulk Elastic Modulus

ABSTRACTThis paper reports on what differentiates the field of soft (i.e. soft-bodied) robotics from the conventional hard (i.e. rigid-bodied) robotics. The main difference centres on seamlessly combining the actuation, sensing, motion transmission and conversion mechanism elements, electronics and power source into a continuum body that ideally holds the properties of morphological computation and programmable compliance (i.e. softness). Another difference is about the materials they are made of. While the hard robots are made of rigid materials such as metals and hard plastics with a bulk elastic modulus of as low as 1 GPa, the monolithic soft robots should be fabricated from soft and hard materials or from a strategic combination of them with a maximum elasticity modulus of 1 GPa. Soft smart materials with programmable mechanical, electrical and rheological properties, and conformable to additive manufacturing based on 3D printing are essential to realise soft robots. Selecting the actuation concept and its power source, which is the first and most important step in establishing a robot, determines the size, weight, performance of the soft robot, the type of sensors and their location, control algorithm, power requirement and its associated flexible and stretchable electronics. This paper outlines how crucial the soft materials are in realising the actuation concept, which can be inspired from animal and plant movements.

Mechanical Testing for Stretchable Electronics

2016 ◽  
Author(s):  
Steven A. Klein ◽  
Aleksandar Aleksov ◽  
Vijay Subramanian ◽  
Rajendra Dias ◽  
Pramod Malatkar ◽  
...  
Keyword(s):  
Mechanical Testing ◽  
Human Body ◽  
Failure Modes ◽  
Mechanical Strain ◽  
Cardiac Activity ◽  
Sun Exposure ◽  
Consumer Electronics ◽  
Test Method ◽  
High Rate ◽  
Stretchable Electronics

Stretchable electronics have been a subject of increased research over the past decade [1–3]. Although stretchable electronic devices are a relatively new area for the semiconductor/electronics industries, recent market research indicates the market could be worth more than 900 million dollars by 2023 [4]. At CES (Consumer Electronics Show) in January 2016, two commercial patches were announced which attach to the skin to measure information about the user’s vitals and environmental conditions [5]. One of these measures the sun exposure of the user with a UV sensitive dye — which can communicate with the user’s cell phone to track the user’s sun exposure. Another device is a re-usable flexible patch which measures cardiac activity, muscle activity, galvanic skin response, and user’s motion. These are just two examples of the many devices that will be developed in the coming years for consumer and medical use. This paper investigates mechanical testing methods designed to test the stretching capabilities of potential products across the electronics industry to help quantify and understand the mechanical integrity, response, and the reliability of these devices. Typically, the devices consist of stiff modules connected by stretchable traces [6]. They require electrical and mechanical connectivity between the modules to function. In some cases, these devices will be subject to bi-axial and/or cyclic mechanical strain, especially for wearable applications. The ability to replicate these mechanical strains and understand their effect on the function of the devices is critical to meet performance, process and reliability requirements. There has been a test method proposed recently for harsh / high-rate testing (shock) of stretchable electronics [7]. The focus of the approach presented in the paper aims to simulate expected user conditions in the consumer and medical fields, whereas earlier research was focused on shock testing. In this paper, methods for simulating bi-axial and out-of-plane strains similar to what may occur in a wearable device on the human body are proposed. Electrical and / or optical monitoring (among other methods) can be used to determine cycles to failure depending on expected failure modes. Failure modes can include trace damage in stretchable regions, trace damage in functional component regions, or bulk stretchable material damage, among others. Three different methods of applying mechanical strain are described, including a stretchable air bladder method, membrane test method, and lateral expansion method. This work will describe a prototype of the air bladder method with initial results of the testing for example devices. The system utilizes an expandable bladder to roughly simulate the expansion of muscles in the human body. Besides strain and # of cycles, other variables such as humidity, temperature, ultraviolet exposure, and others can be utilized to determine their effect on the mechanical and electrical reliability of the devices.

Mechanism of Surface Wrinkle Modulation for a Stiff Film on Compliant Substrate

2017 ◽  
Vol 84 (5) ◽  
Author(s):  
Yilun Liu ◽  
Mengjie Li ◽  
Jingran Liu ◽  
Xi Chen
Keyword(s):  
Soft Materials ◽  
Stretchable Electronics ◽  
Cosmetic Products ◽  
Modulus Ratio ◽  
Surface Wrinkle ◽  
Theoretical Predictions ◽  
Parallel Finite Element ◽  
And Performance ◽  
Film Substrate ◽  
Good Agreement

In this work, the surface wrinkle modulation of the film/substrate system caused by eigenstrain in the film is studied. A theoretical model is proposed which shows the change of the wrinkle amplitude is completely determined by four dimensionless parameters, i.e., the eigenstrain in the film, the plane strain modulus ratio between the film and the substrate, the film thickness to wrinkle wavelength ratio, and the initial wrinkle amplitude to wavelength ratio. The surface wrinkle amplitude becomes smaller (even almost flat) for the contraction eigenstrain in the film, while for the expansion eigenstrain it becomes larger. If the expansion eigenstrain exceeds a critical value, secondary wrinkling on top of the existing one is observed for some cases. In general, the deformation diagram of the wrinkled film/substrate system can be divided into three regions, i.e., the change of surface wrinkle amplitude, the irregular wrinkling, and the secondary wrinkling, governed by the four parameters above. Parallel finite element method (FEM) simulations are carried out which have good agreement with the theoretical predictions. The findings may be useful to guide the design and performance of stretchable electronics, cosmetic products, biomedical engineering, soft materials, and devices.

Microfabricated Instrumented Composite Stamps for Transfer Printing

2015 ◽  
Vol 3 (2) ◽  
Author(s):  
Numair Ahmed ◽  
John A. Rogers ◽  
Placid M. Ferreira
Keyword(s):  
Vantage Point ◽  
Strain Gauges ◽  
Stretchable Electronics ◽  
Adhesion Forces ◽  
Transfer Printing ◽  
Single Cycle ◽  
Flexible Displays ◽  
Materials Integration ◽  
Substrate Interaction ◽  
Nano Scale

Transfer printing is an emerging process that enables micro- and nano-scale heterogeneous materials integration for applications such as flexible displays, biocompatible sensors, stretchable electronics, and others. It transfers prefabricated micro- and nano-scale functional structures, referred to as “ink,” from growth or fabrication donor substrates to functional receiver substrates using a soft polymeric “stamp,” typically made from polydimethylsiloxane (PDMS) with patterned posts for selectively engaging the ink. In high throughput implementations of the process, where several structures or inks are transferred in a single cycle, the ability to detect contact and monitor localized forces at each post during critical events in the printing process allows for the development of a robust and reliable manufacturing process. It also provides a unique vantage point from which to study fundamental issues and phenomena associated with adhesion and delamination of thin films from a variety of substrate materials. In this paper, we present a new composite stamp design consisting of SU-8 cantilevers instrumented with strain gauges, embedded in a thin film of PDMS patterned with posts, and supported by a backing layer. The fabrication of such a stamp, its testing and calibration are discussed. The use of the instrumented stamp in measuring adhesion forces between silicon and PDMS is demonstrated. New modes of programming the print cycle that monitor forces to control the stamp–substrate interaction are also demonstrated. Finally, a classifier-based approach to detecting failed pick-up or release of the ink is developed and demonstrated to work within a transfer printing cycle.

scholarly journals Simple and cost-effective microfabrication of flexible and stretchable electronics for wearable multi-functional electrophysiological monitoring

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Chae Hyun Kim ◽  
Dong Hyeon Lee ◽  
Jiman Youn ◽  
Hongje Lee ◽  
Joonsoo Jeong
Keyword(s):  
Flexible Electronics ◽  
Mechanical Strain ◽  
Cost Effective ◽  
Stretchable Electronics ◽  
Microelectromechanical System ◽  
Sensor Platforms ◽  
Monitoring Applications ◽  
Mems Technology ◽  
Critical Requirement ◽  
Flexible And Stretchable Electronics

AbstractThe fabrication of flexible and stretchable electronics is a critical requirement for the successful application of wearable healthcare devices. Although such flexible electronics have been commonly fabricated by microelectromechanical system (MEMS) technologies, they require a specialised equipment for vacuum deposition, photolithography, and wet and dry etching. A photolithography-free simple patterning method using a desktop plotter cutter has been proposed; however, the metal formation and electrode opening still rely on the MEMS technology. To address this issue, we demonstrate a simple, rapid, cost-effective, and a complete microfabrication process for flexible and stretchable sensor platforms encompassing conductor formation and patterning to encapsulate and open sensing windows, which only require an economic plotter cutter and readily available supplies. Despite its simplicity, the proposed process could stably create microscale features of 200 μm wide conductor lines and 1 mm window openings, which are in the useful range for various wearable applications. The feasibility of the simple fabrication of multi-functional sensors for various physiological monitoring applications was successfully demonstrated in electrochemical (glucose), electrical (electrocardiogram), mechanical (strain), and thermal (body temperature) modalities.

Microengineering of Supramolecular Soft Materials by Design of the Crystalline Fiber Networks

2010 ◽  
Vol 10 (6) ◽  
pp. 2699-2706 ◽  
Author(s):  
Jing-Liang Li ◽  
Bing Yuan ◽  
Xiang-Yang Liu ◽  
Hong-Yao Xu
Keyword(s):  
Soft Materials ◽  
Fiber Networks ◽  
Materials By Design

Extremely Stretchable Supercapacitors Based on Buckled Single-Walled Carbon Nanotube Macro-Films

2009 ◽  
Author(s):  
Cunjiang Yu ◽  
Hanqing Jiang
Keyword(s):  
Carbon Nanotube ◽  
Energy Storage ◽  
Mechanical Strain ◽  
Storage Device ◽  
Stretchable Electronics ◽  
Energy Storage Device ◽  
Single Walled Carbon Nanotube ◽  
Single Walled Carbon ◽  
Cyclic Stretching ◽  
Power Densities

Flexible and stretchable electronics have attracted extensive attention and research efforts recently. As an indispensible component, energy storage device that is able to bear large mechanical strain and be integrated with the stretchable electronics makes the whole system stretchable. Here we report reversibly stretchable supercapacitors using buckled single-walled carbon nanotube (SWNT) macro-films as the electrodes, which have controllable wavy geometries and show extremely high mechanical stretchability with the utility of polydimethylsiloxane (PDMS) as the elastomeric substrates. The stretchable supercapacitors exhibit very stable capacitance under cyclic stretching and releasing, and comparable energy and power densities with those using pristine SWNT macro-films as electrodes.

scholarly journals Straining soft colloids in aqueous nematic liquid crystals

2016 ◽  
Vol 113 (20) ◽  
pp. 5564-5569 ◽  
Author(s):  
Peter C. Mushenheim ◽  
Joel S. Pendery ◽  
Douglas B. Weibel ◽  
Saverio E. Spagnolie ◽  
Nicholas L. Abbott
Keyword(s):  
Liquid Crystals ◽  
Lipid Membrane ◽  
Membrane Surface ◽  
Mechanical Strain ◽  
Thermal Quenching ◽  
Soft Materials ◽  
Shape Transformation ◽  
Membrane Pore ◽  
Aspect Ratios ◽  
Soft Colloids

Liquid crystals (LCs), because of their long-range molecular ordering, are anisotropic, elastic fluids. Herein, we report that elastic stresses imparted by nematic LCs can dynamically shape soft colloids and tune their physical properties. Specifically, we use giant unilamellar vesicles (GUVs) as soft colloids and explore the interplay of mechanical strain when the GUVs are confined within aqueous chromonic LC phases. Accompanying thermal quenching from isotropic to LC phases, we observe the elasticity of the LC phases to transform initially spherical GUVs (diameters of 2–50 µm) into two distinct populations of GUVs with spindle-like shapes and aspect ratios as large as 10. Large GUVs are strained to a small extent (R/r < 1.54, where R and r are the major and minor radii, respectively), consistent with an LC elasticity-induced expansion of lipid membrane surface area of up to 3% and conservation of the internal GUV volume. Small GUVs, in contrast, form highly elongated spindles (1.54 < R/r < 10) that arise from an efflux of LCs from the GUVs during the shape transformation, consistent with LC-induced straining of the membrane leading to transient membrane pore formation. A thermodynamic analysis of both populations of GUVs reveals that the final shapes adopted by these soft colloids are dominated by a competition between the LC elasticity and an energy (∼0.01 mN/m) associated with the GUV–LC interface. Overall, these results provide insight into the coupling of strain in soft materials and suggest previously unidentified designs of LC-based responsive and reconfigurable materials.

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