Millimeter Thin and Rubber‐Like Solid‐State Lighting Modules Fabricated Using Roll‐to‐Roll Fluidic Self‐Assembly and Lamination

Park, Se-Chul; Biswas, Shantonu; Fang, Jun; Mozafari, Mahsa; Stauden, Thomas; Jacobs, Heiko O.

doi:10.1002/adma.201500839

Cited by 31 publications

(25 citation statements)

References 35 publications

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“…A onestep process for directly writing conductive, ductile metal wires and complex 3D architectures, such as freestanding spiral motifs, onto low-cost plastic and rigid substrates would enable highperformance, customizable electronic and other devices to be manufactured in a cost-effective and space-efficient manner. To date, several printing approaches have been developed to directly deposit conductive features, including roll-to-roll (17)(18)(19), inkjet printing (20,21), meniscus printing (8), and direct ink writing (DIW) (1,22). Although DIW has demonstrated spanning linear traces or short arcs printed out-of-plane, only meniscus-based electrodeposition printing has been used to generate freestanding 3D solid metal structures in arbitrary geometries.…”

mentioning

confidence: 99%

Laser-assisted direct ink writing of planar and 3D metal architectures

Skylar‐Scott

Gunasekaran

Lewis

2016

Proc. Natl. Acad. Sci. U.S.A.

276

199

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The ability to pattern planar and freestanding 3D metallic architectures at the microscale would enable myriad applications, including flexible electronics, displays, sensors, and electrically small antennas. A 3D printing method is introduced that combines direct ink writing with a focused laser that locally anneals printed metallic features "on-the-fly." To optimize the nozzle-to-laser separation distance, the heat transfer along the printed silver wire is modeled as a function of printing speed, laser intensity, and pulse duration. Laser-assisted direct ink writing is used to pattern highly conductive, ductile metallic interconnects, springs, and freestanding spiral architectures on flexible and rigid substrates. T he ability to create planar and freestanding 3D metal structures on demand at the microscale would enable myriad applications, including electronics (1-8), microelectromechanical systems (MEMS) (9, 10), metamaterials (11-13), and biomedical devices (14-16). For example, many electronic devices, such as inductors and antennas (4, 7), operate more efficiently in 3D form. However, that format is not well suited to standard photolithographic techniques. A onestep process for directly writing conductive, ductile metal wires and complex 3D architectures, such as freestanding spiral motifs, onto low-cost plastic and rigid substrates would enable highperformance, customizable electronic and other devices to be manufactured in a cost-effective and space-efficient manner. To date, several printing approaches have been developed to directly deposit conductive features, including roll-to-roll (17-19), inkjet printing (20, 21), meniscus printing (8), and direct ink writing (DIW) (1,22). Although DIW has demonstrated spanning linear traces or short arcs printed out-of-plane, only meniscus-based electrodeposition printing has been used to generate freestanding 3D solid metal structures in arbitrary geometries. However, its ultralow print speed (<1 μm/s) coupled with the need for a conductive substrate have limited its widespread adoption (8).Here, we introduce laser-assisted direct ink writing (laser-DIW), which combines printing of concentrated silver nanoparticle inks with focused infrared laser annealing to rapidly create high conductivity, ductile metallic wires and 3D architectures "on-the-fly" in a one-step, additive process. Laser-DIW offers three key advantages over other 3D printing techniques. First, by combining patterning and annealing in a single step, the printed metallic features exhibit the requisite mechanical properties needed to precisely fabricate arbitrary objects in midair, enabling complex curvilinear structures to be generated without the need for support material. Due to localized annealing, such features can be printed on low-cost plastic substrates, such as poly(ethylene terphthalate) (PET). Finally, the patterned features exhibit high electrical conductivity approaching that of bulk silver. Results and DiscussionDuring laser-DIW, an 808-nm IR laser is focused to a 100-μm spot adjacent ...

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confidence: 99%

Laser-assisted direct ink writing of planar and 3D metal architectures

Skylar‐Scott

Gunasekaran

Lewis

2016

Proc. Natl. Acad. Sci. U.S.A.

276

199

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“…The required strong adhesion to the rubber matrix and metallization layer is achieved by plasma activation of the polyimide surface (30 SCCM, O 2 , 100 W for 2 min). (ii) Stretchable Metal Track Layer : For the metallization layer we used a 20 nm/200 nm thick sputter‐coated seed layer of Ti/Cu, which is patterned by photolithography. We used a 10 µm thick layer of electroplated Cu to increase the mechanical robustness of the metal tracks (reddish layer); thick metal tracks (>5 µm) were found to be more robust than previously used thin (<1 µm) metallization layers . Our previous attempts to produce the demonstrator using thin metallization layers failed. (iii) Reinforcing Metal Track Cladding : A second 10 µm thick PI layer (PI 2611) is spin‐coated on top of the metal tracks and patterned by photolithography.…”

Section: Methodsmentioning

confidence: 99%

3D Metamorphic Stretchable Microphone Arrays

Biswas

Reiprich

Cohrs

et al. 2017

Adv Materials Technologies

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and form factor. To the best of our knowledge, a metamorphic microphone array has not been reported. Within the field of metamorphic electronics, two fabrication strategies are commonly used. The first uses electronic devices in combination with a bendable carrier and bendable interconnects. Here origami- [2] and kirigami [3] like methods are used to fold the structure into a desired shape. The topological complexity dictates the number of folds that are required and certain topologies, for example, a sphere, and are difficult to fabricate. The microphone arrays discussed in this communication morph from a (i) concave to a (ii) planar to a (iii) convex and a (iv) cone-like topology, which would be very difficult to achieve using the origami/kirigami approach.An alternative to the origami-inspired method is to build on recent advancements in the field of stretchable electronics. Stretchable electronics incorporates electronic functions (in our case, microphones and other active and passive devices) inside or on top of a stretchable elastomeric membrane. One essential element is the requirement of stretchable electrical interconnects between the device elements. Different interconnect solutions are known today. Most of the solutions go back to the original work by Lacour, [4] Chen, [5] and Whitesides [6] and their respective co-workers who reported (i) metallization layers with topological wrinkles, [4] (ii) meander or horse-shoe designs, [5] and (iii) liquid metals, [6] as the stretchable interconnecting metal layers, respectively. A large set of applications have been demonstrated, which include smart clothing, [7] conformable photo voltaics, [8] optoelectronics, [9] digital cameras, [10] artificial electronic skins, [11] stretchable batteries, [12] robotics, [13] and mechanically soft and conformable health-monitoring devices [14] to give a few recent examples. However, considering the current state of the art, the number of interconnects to the isolated device elements has been small (2-4 connections per device), and the total number of devices continues to be limited (5-22 devices). [15] This points to scaling and robustness challenges.As a result, the desired microphone array has been difficult to fabricate using the reported methods. The array has a total number of 60 interconnects, contains 5 different device types, and a total of 25 commercially available surface mount devices (SMDs). This goes beyond the metrics previously reported in the field of stretchable electronics.This article describes the realization of a metamorphic microphone array. The array morphs from a concave to a planar and then to a convex shape. The morphing array enables a better (12×) sound source localization when compared to existing static and planar arrangements. To enable the realization, a novel stretchable (elongated up to 320% of the original length) printed circuit board fabrication process is reported. The fabrication process enables high-temperature processing, alignment, and registration. Moreover, conventional and otherw...

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“…The device was used for thermotherapy, wherein non-stretchable islands of copper coils interconnected with stretchable lateral springs heat upon the application of voltage for pain relief. Various other studies have used copper as a metal layer on either polyimide, polyethylene naphthalate or PDMS for various applications, such as thermotherapy [165] , EEG recording [166] , RF interconnects [167] , lighting modules [168] and thin film inductors [169] . This design has also been successfully applied using other metal thin films, such as gold [170] , aluminum [171] , silver [172] , AgNWs [173] and ITO [174,175] .…”

Section: Fractal Serpentine Structuresmentioning

confidence: 99%