Printable Graphene-Sustainable Elastomer-Based Cross Talk Free Sensor for Point of Care Diagnostics.

Developing sensors for monitoring physiological parameters such as temperature and strain for point of care (POC) diagnostics is critical for better care of the patients. Various commercial sensors are available to get the job done; however, challenges like the structural rigidity of such sensors confine their usage. As an alternative, flexible sensors have been looked upon recently. In most cases, flexible sensors cannot discriminate the signals from different stimuli. While there have been reports on the printable sensors providing cross-talk-free solutions, research related to developing sensors from a sustainable source providing discriminability between signals is not well-explored. Herein, we report the development of a stencil printable composition made of graphene and epoxidized natural rubber. The stencil printability index was vetted using rheological studies. Post usage, the developed sensor was dissolved in an organic solvent at room temperature. This, along with the choice of a sustainable elastomer, warrants the minimization of electronic waste and carbon footprint. The developed material demonstrated good conformability with the skin and could perceive and decouple the signals from temperature and strain without inducing any crosstalks. Using a representative volume element model, a comparison between experimental findings and computation studies was made. The developed sensors demonstrated gauge factors of -506 and 407 in the bending strain regimes of 0-0.04% and 0.04%-0.09%, respectively, while the temperature sensitivity was noted to be -0.96%/°C. The printed sensors demonstrated a multifunctional sensing behavior for monitoring various active physiological parameters ranging from temperature, strain, pulse, and breathing to auditory responses. Using a Bluetooth module, various parameters like temperature and strain could be monitored seamlessly in a smart-phone. The current development would be crucial to open new avenues to fabricate crosstalk-free sensors from sustainable sources for POC diagnostics.

Kirigami-inspired metamaterials for programming constitutive laws: Mixed-mode multidirectional auxeticity and contact-induced stiffness modulation.

Stress-strain constitutive relations and Poisson's ratios are fundamental properties of naturally occurring materials, based on which their mechanical applications can be designed. The lack of tailorability and restricted margin for such critical properties severely limit the bounds of achievable multi-functional engineering designs using conventional materials. Through analytical and numerical analyses, supported by elementary-level physical experiments, we have proposed a kirigami-inspired hybrid metamaterial with programmable deformation-dependent stiffness and mixed-mode multidirectional auxeticity. The metamaterial can transition from a phase of low stiffness to a contact induced phase that brings forth an extensive rise in stiffness. Uniform and graded configurations of multi-layer tessellated material are developed to modulate the constitutive law of the metastructure with augmented programmability in two- and three-dimensional spaces. The proposed metamaterial will lead to extreme lightweight functional designs for impact resistance, shape morphing, multidirectional deformation, vibration and wave propagation control, where the capabilities of intrinsic material can be most optimally exploited.

Probing the chirality-dependent elastic properties and crack propagation behavior of single and bilayer stanene.

Stanene, a quasi-two-dimensional honeycomb-like structure of tin belonging to the family of 2D-Xenes (X = Si, Ge, Sn) has recently been reported to show promising electronic, optical and mechanical properties. This paper investigates the elastic moduli and crack propagation behaviour of single layer and bilayer stanene based on molecular dynamics simulations, which have been performed using the Tersoff bond order potential (BOP). We have parameterized the interlayer van der Waals interactions for the bilayer Lennard-Jones potential in the case of bilayer stanene. Density functional calculations are performed to fit the Lennard-Jones parameters for the properties which are not available from the scientific literature. The effect of temperature and strain rate on the mechanical properties of stanene is investigated for both single layer and bilayer stanene in the armchair and zigzag directions. The results reveal that both the fracture strength and strain of stanene decrease with increasing temperature, while at higher loading rate, the material is found to exhibit higher fracture strength and strain. The effect of chirality on the elastic moduli of stanene is explained on the basis of a physics-based analytical approach, wherein the fundamental interaction between the shear modulus and Young's modulus is elucidated. To provide a realistic perspective, we have investigated the compound effect of uncertainty on the elastic moduli of stanene based on an efficient analytical approach. Large-scale Monte Carlo simulations are carried out considering different degrees of stochasticity. The in-depth results on mechanical properties presented in this article will further aid the adoption of stanene as a potential nano-electro-optical substitute with exciting features such as 2D topological insulating properties with a large bandgap, the capability to support enhanced thermoelectric performance, topological superconductivity and a quantum anomalous Hall effect at near-room-temperature.

Contralateral contiguous tuberculous lymphadenitis in a case of right breast carcinoma--Diagnostic dilemma.

Coexistence of tuberculosis (TB) in the breast or axillary lymph nodes with breast carcinoma though rare is not unknown. A 55-year-old woman presented with right axillary and left supraclavicular lymphadenopathies with no detectable lesion in either breasts or left axilla. Right axillary lymph node excision biopsy revealed metastatic adenocarcinoma. Diagnostic workup showed intense fluorodeoxyglucose (FDG)-avid lymph nodes on the left side neck at level V, supraclavicular, axillary, subpectoral and para-aortic regions, and low FDG activity in the right breast. Core biopsy of right breast lesion was reported as invasive ductal carcinoma and cytology of multiple left axillary lymphadenopathies as reactive hyperplasia. Excision biopsy of the supraclavicular lymph nodes unveiled the diagnosis of TB. She underwent right-modified radical mastectomy followed by external beam radiotherapy, has completed antituberculous treatment and is on follow-up. Extrapulmonary TB though uncommon; may be found in certain cases. Clinicians must be aware of its existence.