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Wafer‐scale and layered MoS2 films are grown by sulfurizing amorphous MoS2 films deposited on sapphire substrates by using a radio‐frequency sputtering system. To verify the layer numbers of the multi‐layer MoS2 films, atomic layer etchings are adopted. Wafer‐scale MoS2 film growth with good layer number uniformity up to 30 is observed. A vertical device with 20‐layer MoS2 embedded in between Al (bottom) and Au (top) electrodes is fabricated. With different work functions of the metal electrodes, photo‐excited electrons and holes in the MoS2 layer can be separated and form photovoltaic responses. With the insertion of 5 nm MoO3 carrier transport layer between the MoS2 layer and the top Au electrode, enhanced photovoltaic responses are observed for the device. By using graphene as the carrier transport layer and MoS2 as the light absorption layer, avalanche photocurrents are observed for planar MoS2/graphene photoconductive devices. With the assist of the higher electron density in multi‐layer MoS2, an easier compensation in the loss of photo‐excited electrons and therefore, charge neutrality in the MoS2 layer can be maintained. Significant reduction in the rise/fall times from >100 ms. to <10 ms. is also observed for the planar photodetector with 10‐layer MoS2 absorption layer. Wafer‐scale and uniform multi‐layer MoS2 can be prepared by sulfurizing amorphous MoS2 films. The MoS2 film can act as light absorption layer in vertical device architecture and exhibit photovoltaic responses. With separate light absorption (multi‐layer MoS2) and carrier transport (mono‐layer graphene) layers in planar device architecture, high responsivity and short response times can be achieved.

To pinpoint the electronic and structural mechanisms that affect intrinsic and extrinsic performance limits of 2D material devices, it is of critical importance to resolve the electronic properties on the mesoscopic length scale of such devices under operating conditions. Herein, angle‐resolved photoemission spectroscopy with nanoscale spatial resolution (nanoARPES) is used to map the quasiparticle electronic structure of a twisted bilayer graphene device. The dispersion and linewidth of the Dirac cones associated with top and bottom graphene layers are determined as a function of spatial position on the device under both static and operating conditions. The analysis reveals that microscopic rotational domains in the two graphene layers establish a range of twist angles from 9.8° to 12.7°. Application of current and electrostatic gating lead to strong electric fields with peak strengths of 0.75 V/μm at the rotational domain boundaries in the device. These proof‐of‐principle results demonstrate the potential of nanoARPES to link mesoscale structural variations with electronic states in operating device conditions and to disentangle such extrinsic factors from the intrinsic quasiparticle dispersion. Nanoscale angle‐resolved photoemission spectroscopy is applied to map the electronic structure of a twisted bilayer graphene device during the application of current and an electrostatic gate voltage. Rotational domains are found to strongly affect the measured linewidth of the top and bottom Dirac cones and lead to a spatially inhomogeneous electric field during operation of the device.

Herein we describe the use of a new DNAzyme/graphene hybrid material as a biointerfaced sensing platform for optical detection of pathogenic bacteria. The hybrid consists of a colloidal graphene nanomaterial and an Escherichia coli-activated RNA-cleaving DNAzyme and is prepared via non-covalent self-assembly of the DNAzyme onto the graphene surface. Exposure of the hybrid material to E. coli-containing samples results in the release of the DNAzyme, followed by the cleavage-mediated production of a fluorescent signal. Given that specific RNA-cleaving DNAzymes can be created for diverse bacterial pathogens, direct interfacing of graphene materials with such DNAzymes represents a general and attractive approach for real-time, sensitive, and highly selective detection of pathogenic bacteria.

Graphene-based electronic DNA sequencing techniques have received significant attention over the past decade and are hoped to provide a new generation of portable, low-cost devices capable of rapid and accurate DNA sequencing. However, these devices are yet to demonstrate DNA sequencing. This is partly due to complex fabrication requirements resulting in low device yields and limited throughput. In this paper, we review the challenging fabrication of graphene-based electronic DNA sequencing devices. We will place a particular focus on common fabrication challenges and look toward the development of high-throughput, high-yield fabrication of these devices.

The inefficiencies of the current pipeline from discovery to clinical approval of drugs demand a surrogate method to indicate adverse drug reactions, e.g. liver damage. Organ-on-chip (OOC) models would be an ideal, rapid, and human-specific alternate, which would render animal testing obsolete. The ground-breaking ability of OOCs and Multi-OOC constructs is the accurate simulation of the in vivo conditions of human organs leading to precise drug screens for cytotoxicity and/or drug efficacy at a faster pace and lesser cost. Here we discuss the innovation, architecture, and the progress of OOCs towards human body-on-a-chip.

Wearable healthcare technologies should be non-invasive, robust to daily activity/environments, easy to use, and comfortable to wear. Flexible substrate devices for biomarker monitoring can contribute to wearable diagnostic applications. Single-target biosensors have extensively been developed for health-monitoring applications; however, recently multiplex biomarker tests have generated clinical interest. Targeting multiple biomarkers in diagnostic systems (wearable or point of care) offers more focused diagnosis and treatment as changes in a single biomarker can be caused by a series of physiologic conditions. This review highlights flexible substrates that have been successfully demonstrated for multiplex biomarker detection with potential for healthcare monitoring.

We report results of the studies relating to the development of the emerging nanostructured molybdenum trioxide (nMoO3)-based biocompatible label-free biosensing platform for breast cancer detection. The structural and morphological studies of the synthesized nMoO3 nanorods were investigated by XRD, SEM, X-ray photoelectron spectroscopic, and TEM techniques. This biocompatible one-dimensional (1D) nMoO3-based biosensing platform exhibited high sensitivity (0.904 µAmL/ng/cm2), wide linear detection range (2.5–110 ng/mL), and a lower detection limit as 2.47 ng/mL toward human epidermal growth factor receptor-2 detection. The results obtained using this sensor platform on serum samples of breast cancer patients were validated using ELISA.

High-performance electrochemical hydrogen peroxide (H2O2) sensors based on PdAg nanoparticle-decorated reduced graphene oxide (rGO) and multi-walled carbon nanotube (MWCNT) hybrids were developed. The nanostructures were characterized using transmission electron microscopy, scanning electron microscopy, energy-dispersive spectroscopy, thermogravimetric analysis, Fourier transform spectroscopy, and x-ray diffraction techniques. It was found that introduction of MWCNT in the catalyst layer improved the sensitivity and widened the linear range. Sensitivities of 393.2, 437.1, and 576.6 µA/mM/cm2 were obtained for PdAg/rGO–MWCNT (2:1), PdAg/rGO–MWCNT (1:1), and PdAg/rGO–MWCNT (1:2), respectively. Furthermore, hierarchical structure of rGO–MWCNT nanohybrids enabled the detection of H2O2 up to 80 mM.

Metal–graphene composites are sought after for various applications. A hybrid light-weight foam of nickel (Ni) and reduced graphene oxide (rGO), called Ni-rGO, is reported here for small molecule oxidations and thereby their sensing. Methanol oxidation and non-enzymatic glucose sensing are attempted with the Ni-rGO foam via electrocatalytically, and an enhanced methanol oxidation current density of 4.81 mA/cm2 is achieved, which is ~1.7 times higher than that of bare Ni foam. In glucose oxidation, the Ni-rGO electrode shows a better sensitivity over bare Ni foam electrode where it could detect glucose linearly over a concentration range of 10 µM to 4.5 mM with a very low detection limit of 3.6 µM. This work demonstrates the synergistic effects of metal and graphene in oxidative processes, and also shows the feasibility of scalable metal–graphene composite inks development for small molecule printable sensors and fuel cell catalysts.