It is challenging to achieve highly efficient thermoelectric materials due to the conflicts between thermopower (Seebeck coefficient) and electrical conductivity. These parameters are the core factors defining the thermoelectric property of any material. Here, we report the use of isovalent substitution as a tool to decouple the interdependency of the Seebeck coefficient and the electrical properties of cerium-doped bismuth selenide thermoelectric material. With this strategy, we can achieve a simultaneous increase in both the electrical conductivity and the Seebeck coefficient of the material by tuning the concentration of cerium doping, due to formation of neutral impurities and consequently the improvement of carrier mobility. Our theoretical calculation reveals a downward shift of the valence band with cerium concentration, which influences the thermoelectric enhancement of the synthesized materials. Finally, an order of magnitude enhancement of the figure of merit is obtained due to isovalent substitution, thus providing a new avenue for enhancing the thermoelectric performance of materials.

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Facile and efficient early detection of cancer is a major challenge in healthcare. Herein we developed a novel sensor made from a polycarbonate (PC) membrane with nanopores, followed by sequence-specific Oligo RNA modification for early gastric carcinoma diagnosis. In this design, the gastric cancer antigen CA72-4 is specifically conjugated to the Oligo RNA, thereby inhibiting the electrical current through the PC membrane in a concentration-dependent manner. The device can determine the concentration of cancer antigen CA72-4 in the range from 4 to 14 U/mL, possessing a sensitivity of 7.029 µAU−1mLcm−2 with a linear regression (R2) of 0.965 and a lower detection limit of 4 U/mL. This device has integrated advantages including high specificity and sensitivity and being simple, portable, and cost effective, which collectively enables a giant leap for cancer screening technologies towards clinical use. This is the first report to use RNA aptamers to detect CA72-4 for gastric carcinoma diagnosis.

There is an ever-growing need for more advanced methods to study the response of cancer cells to new therapies. To determine cancer cells' response from a cell-mortality perspective to various cancer therapies, we report a label-free and real time method to monitor the in-situ response of individual HeLa cells using a Single Cell Gated Transistor (SCGT). As a cell undergoes apoptotic cell death, it experiences changes in morphology and ion concentrations. This change is well in line with the threshold voltage of the SCGT, which has been verified by correlating the data with the cell morphologies by scanning electron microscopy and the ion-concentration analysis by ICP-MS. This SCGT could replace patch clamps to study single cell activity via direct measurement in real time. Importantly, this SCGT can be used to study the electrical response of a single cell to stimuli that leaves the membrane intact.

In SrTiO3, the nature of dopants and their substitution at the A or B site becomes a critical factor in determining the electrical conductivity, Seebeck coefficient, and thermal conductivity. The electronic band structure and the density of states (DOS) for the ab-initio study using different dopants were estimated using PBE-GGA approximation. The size, site of substitution, and nature of dopants cause significant changes in the lattice dimensions, band structure, band curvatures, and the density of states, which reflect as changes in the effective mass m B i ⁎ . The effective mass m B i ⁎ is calculated from the curvature of the bottom-most conduction band using the one-band effective mass approximation. Pentavalent substitutions on the B site of SrTiO3 affect the conduction band’s curvature differently than with trivalent substitutions on the A site. They also exhibit an opposite trend in the change in band curvature according to the dopant’s ionic radius. In contrast, isovalent dopants showed no change in the band curvature except for the bandgap modification. In this paper, we have provided a semi-quantitative understanding regarding the thermoelectric properties like conductivity and Seebeck coefficient that get affected due to the substituent’s nature and site at which it substitutes.