Toward CMOS image sensor based glucose monitoring

Complementary metal oxide semiconductor (CMOS) image sensor is a powerful tool for biosensing applications. In this present study, CMOS image sensor has been exploited for detecting glucose levels by simple photon count variation with high sensitivity. Various concentrations of glucose (100 mg dL(-1) to 1000 mg dL(-1)) were added onto a simple poly-dimethylsiloxane (PDMS) chip and the oxidation of glucose was catalyzed with the aid of an enzymatic reaction. Oxidized glucose produces a brown color with the help of chromogen during enzymatic reaction and the color density varies with the glucose concentration. Photons pass through the PDMS chip with varying color density and hit the sensor surface. Photon count was recognized by CMOS image sensor depending on the color density with respect to the glucose concentration and it was converted into digital form. By correlating the obtained digital results with glucose concentration it is possible to measure a wide range of blood glucose levels with great linearity based on CMOS image sensor and therefore this technique will promote a convenient point-of-care diagnosis.     

Organic transistors in the new decade: Toward n-channel,printed, and stabilized devices

Significant progress has been made in designing organic semiconducting materials (OSCs) for the past few decades for organic field-effect transistors (OFETs). Much attention has been paid to the development of p-channel OSCs, with less but highly significant progress on n-channel OSCs. In this review, we focus on the advances made with OFETs in the last few years to achieve high performance in n-channel modes, air stability, and solution processability, leading to printable active electronics. © 2012 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys, 2012     

Escape times for branching processes with random mutational fitness effects

We consider a large declining population of cells under an external selection pressure, modeled as a subcritical branching process. This population has genetic variation introduced at a low rate which leads to the production of exponentially expanding mutant populations, enabling population escape from extinction. Here we consider two possible settings for the effects of the mutation: Case (I) a deterministic mutational fitness advance and Case (II) a random mutational fitness advance. We first establish a functional central limit theorem for the renormalized and sped up version of the mutant cell process. We establish that in Case (I) the limiting process is a trivial constant stochastic process, while in Case (II) the limit process is a continuous Gaussian process for which we identify the covariance kernel. Lastly we apply the functional central limit theorem and some other auxiliary results to establish a central limit theorem (in the large initial population limit) of the first time at which the mutant cell population dominates the population. We find that the limiting distribution is Gaussian in both Cases (I) and (II), but a logarithmic correction is needed in the scaling for Case (II). This problem is motivated by the question of optimal timing for switching therapies to effectively control drug resistance in biomedical applications.     

A CMOS image sensor to recognize the cardiovascular disease markers troponin I and C-reactive protein

A complementary metal oxide semiconductor (CMOS) image sensor was utilized to detect the interaction of cardiovascular disease markers, troponin I and C-reactive protein. Each marker with its respective antibodies was adsorbed to an indium nanoparticle (InNP)-coated glass substrate. Dielectric layers of antigens and antibodies bound onto and interacted on conducting InNPs. Normal room light passed through these protein-layer-bound substrates and hit the CMOS image sensor surface, and the number of photons was detected and converted into digital form. We tested this approach for real-time monitoring of cardiac disease markers based on photon count, demonstrating its low cost and its capacity to detect antigens with high sensitivity at picogram per milliliter concentration.     

Complementarity Paradox Solved: Surprising Consequences

Afshar et al. claim that their experiment shows a violation of the complementarity inequality. In this work, we study their claim using a modified Mach-Zehnder setup that represents a simpler version of the Afshar experiment. We find that our results are consistent with Afshar et al. experimental findings. However, we show that within standard quantum mechanics the results of the Afshar experiment do not lead to a violation of the complementarity inequality. We show that their claim originates from a particular technique they use to analyze their results. In their analysis, they assume a classical concept, that particles have a definite trajectory before detection, thus, they obtain which-way information by particle detection plus path extrapolation by applying momentum conservation. This analysis technique is standard in experimental particle physics. Important discoveries such as the detection of vector bosons have been made through the application of this technique. We note that particle detection plus path extrapolation is a suitable technique within de Broglie-Bohm theory of quantum mechanics.