Metal-organic frameworks (MOFs) are typically highlighted for their potential application in gas storage, separations and catalysis. In contrast, the unique prospects these porous and crystalline materials offer for application in electronic devices, although actively developed, are often underexposed. This review highlights the research aimed at the implementation of MOFs as an integral part of solid-state microelectronics. Manufacturing these devices will critically depend on the compatibility of MOFs with existing fabrication protocols and predominant standards. Therefore, it is important to focus in parallel on a fundamental understanding of the distinguishing properties of MOFs and eliminating fabrication-related obstacles for integration. The latter implies a shift from the microcrystalline powder synthesis in chemistry labs, towards film deposition and processing in a cleanroom environment. Both the fundamental and applied aspects of this two-pronged approach are discussed. Critical directions for future research are proposed in an updated high-level roadmap to stimulate the next steps towards MOF-based microelectronics within the community.

/pdf/an-updated-roadmap-for-the-integration-of-metal-organic-4ryw3jm11n.pdf

An updated roadmap for the integration of metal–organic frameworks with electronic devices and chemical sensors

Flexible and stretchable electronics and optoelectronics configured in soft, water resistant formats uniquely address seminal challenges in biomedicine. Over the past decade, there has been enormous progress in the materials, designs, and manufacturing processes for flexible/stretchable system subcomponents, including transistors, amplifiers, bio-sensors, actuators, light emitting diodes, photodetector arrays, photovoltaics, energy storage elements, and bare die integrated circuits. Nanomaterials prepared using top-down processing approaches and synthesis-based bottom-up methods have helped resolve the intrinsic mechanical mismatch between rigid/planar devices and soft/curvilinear biological structures, thereby enabling a broad range of non-invasive, minimally invasive, and implantable systems to address challenges in biomedicine. Integration of therapeutic functional nanomaterials with soft bioelectronics demonstrates therapeutics in combination with unconventional diagnostics capabilities. Recent advances in soft materials, devices, and integrated systems are reviewes, with representative examples that highlight the utility of soft bioelectronics for advanced medical diagnostics and therapies.

Recent Advances in Flexible and Stretchable Bio-Electronic Devices Integrated with Nanomaterials.

Memristors are two-terminal passive circuit elements that have been developed for use in non-volatile resistive random-access memory and may also be useful in neuromorphic computing. Memristors have higher endurance and faster read/write times than flash memory and can provide multi-bit data storage. However, although two-terminal memristors have demonstrated capacity for basic neural functions, synapses in the human brain outnumber neurons by more than a thousandfold, which implies that multi-terminal memristors are needed to perform complex functions such as heterosynaptic plasticity. Previous attempts to move beyond two-terminal memristors, such as the three-terminal Widrow-Hoff memristor and field-effect transistors with nanoionic gates or floating gates, did not achieve memristive switching in the transistor. Here we report the experimental realization of a multi-terminal hybrid memristor and transistor (that is, a memtransistor) using polycrystalline monolayer molybdenum disulfide (MoS2) in a scalable fabrication process. The two-dimensional MoS2 memtransistors show gate tunability in individual resistance states by four orders of magnitude, as well as large switching ratios, high cycling endurance and long-term retention of states. In addition to conventional neural learning behaviour of long-term potentiation/depression, six-terminal MoS2 memtransistors have gate-tunable heterosynaptic functionality, which is not achievable using two-terminal memristors. For example, the conductance between a pair of floating electrodes (pre- and post-synaptic neurons) is varied by a factor of about ten by applying voltage pulses to modulatory terminals. In situ scanning probe microscopy, cryogenic charge transport measurements and device modelling reveal that the bias-induced motion of MoS2 defects drives resistive switching by dynamically varying Schottky barrier heights. Overall, the seamless integration of a memristor and transistor into one multi-terminal device could enable complex neuromorphic learning and the study of the physics of defect kinetics in two-dimensional materials.

Multi-terminal memtransistors from polycrystalline monolayer molybdenum disulfide

As one member of the emerging class of ultrathin two-dimensional (2D) transition-metal dichalcogenide (TMD) nanomaterials, the ultra-thin MoS2 nanosheet has attracted increasing research interest as a result of its unique structure and fascinating properties. Solution-phase methods are promising for the scalable production, functionalization, hybridization of MoS2 nanosheets, thus enabling the widespread exploration of MoS2 -based nanomaterials for various promising applications. In this Review, an overview of the recent progress of solution-processed MoS2 nanosheets is presented, with the emphasis on their synthetic strategies, functionalization, hybridization, properties, and applications. Finally, the challenges and opportunities in this research area will be proposed.

Solution-Processed Two-Dimensional MoS2 Nanosheets: Preparation, Hybridization, and Applications.

Extensive research on two-dimensional (2D) materials has triggered the renaissance of an old topic, that is, the intercalation and exfoliation of layer materials. Such top-down exfoliation produced 2D materials and their dispersions have several advantages including low cost, scalable production capability, solution processability, and versatile functionalities stemming from the large number of species of layer materials, and show promising potential in many applications. In recent years, many new methods have been developed for exfoliating layer materials to 2D materials for different application purposes. In this review the different exfoliation approaches are first systematically analyzed from the viewpoint of methodology, and the advantages and disadvantages of each method are compared. Second, the assembly of exfoliated 2D materials into macrostructures by solution-based techniques is summarized. Third, the state-of-the-art applications of 2D material dispersions and their assemblies in electronics and optoelectronics, electrocatalysis, energy storage, etc., are discussed. Finally, insights and perspectives on current research challenges and future opportunities regarding the exfoliation and applications of 2D materials in dispersions are considered.

Preparation of 2D material dispersions and their applications

Memristors promise to emulate the appealing characteristics of biological neural systems. Solution-processed heterostructures are now shown to behave as memristive and memcapacitive switches compatible with printed electronics applications.

Layered memristive and memcapacitive switches for printable electronics

The present invention may relate to provision of a mechanism to join together the various substrate layers of a flexible display with optically clear adhesives that permit improved flexibility of the substrate layer stack and may also optically guide images to locations on a display surface that are not aligned with the display layer of a substrate layer stack. Embodiments of the present invention may provide for an improved user interface which may include enhanced flexibility and enhanced optical characteristics.

Method and apparatus for joining together multiple functional layers of a flexible display

According to aspects of the present disclosure there is provided an apparatus and method for sensing. The apparatus comprisesa sensor circuit which comprises:a first output terminal, a second output terminal anda sensor that is provided in a bridge circuit arrangement. The sensor circuit is configured such that a sensor measurement can be determined based on a voltage difference between first and second output terminals. The apparatus is configured so as to prevent a current from being able to flow from the first output terminal through the sensor circuit to the second output terminal.

An apparatus and method for sensing

An apparatus comprising: a flexible substrate; and an overhanging electronic component island, the electronic component island configured to be less flexible than the flexible substrate and comprising one or more electronic components, wherein the electronic component island comprises a substrate-face with a connection portion and an overhang portion, the connection portion being mechanically coupled to a surface of the flexible substrate via a single connection-support pad and the overhang portion configured to overhang and be substantially free of the underlying flexible substrate such that the underlying flexible substrate can be strained independently from the overhang portion under operational strains of the flexible substrate.

Mark Allen

Papers

Layered memristive and memcapacitive switches for printable electronics

Method and apparatus for joining together multiple functional layers of a flexible display

An apparatus and method for sensing

Flexible electronics apparatus and associated methods

66-4: Invited Paper: Graphene Enhanced QD Image Sensor Technology