Monitoring protein denaturation using thermal conductivity probe

We propose a method for probing denaturation of proteins by measuring the thermal conductivity of the solution. We use the three-omega method with a microfabricated ac thermal sensor to measure the thermal conductivity of lysozyme, beta-lactoglobulin, and bovine serum albumin protein solutions over a range of temperature and pH. Results suggest that conformation transformation of the protein during denaturation changes the thermal network in protein solutions and thus changes the thermal conductivity for all the tested proteins. The proposed method of denaturation monitoring requires much simpler experimental setup than conventional methods such as differential scanning calorimetry and circular dichroism detection. We also demonstrate that the proposed analytical technique can detect the protein denaturation in real time. Consequently, it is expected to be useful in lab-on-a-chip (LoC) applications as the probe can be easily miniaturized for integration into LoC devices and allows real-time analysis. (C) 2012 Elsevier B.V. All rights reserved.X1177sciescopu

Development of a thermal sensor to probe cell viability and concentration in cell suspensions

This paper presents a novel biothermal sensor to probe cell viability and concentration of a cell suspension. The sensing technique exploits the thermophysical properties of the suspension, so no labeling of suspended cells is required. When the sensor is periodically heated, the amplitude and phase of the thermal signal are dependent on the thermal properties of the cell suspension, particularly the thermal conductivity k. We measured k of HeLa, hepatocyte, and NIH-3T3 J2 cell suspensions with various concentrations and viabilities. The results demonstrate that the k of a cell suspension has a strong correlation with its concentration and viability. Accordingly, k can be employed as an index of cell concentration and viability. Furthermore, without data processing to obtain k, the electric signal that reflects the thermal response of the sensor can be used as a tool to probe viability of a cell suspension in real time. The proposed thermal sensing technique offers label-free, non-invasive, long-term, and real-time means to probe the viability and concentration of cells in a suspension

Analysis of Disparity Information for Depth Extraction Using CMOS Image Sensor with Offset Pixel Aperture Technique

A complementary metal oxide semiconductor (CMOS) image sensor (CIS), using offset pixel aperture (OPA) technique, was designed and fabricated using the 0.11-µm CIS process. In conventional cameras, an aperture is located on the camera lens. However, in a CIS camera using OPA technique, apertures are integrated as left-offset pixel apertures (LOPAs) and right-offset pixel apertures (ROPAs). A color pattern is built, comprising LOPA, blue, red, green, and ROPA pixels. The disparity information can be acquired from the LOPA and ROPA channels. Both disparity information and two-dimensional (2D) color information can be simultaneously acquired from the LOPA, blue, red, green, and ROPA channels. A geometric model of the OPA technique is constructed to estimate the disparity of the image, and the measurement results are compared with the estimated results. Depth extraction is thus achieved by a single CIS using the OPA technique, which can be easily adapted to commercial CIS cameras