High-resolution CMOS Camera Research Articles

Laser speckle contrast imaging of cerebral blood flow in freely moving animals

We designed a miniature laser speckle imager that weighs ∼20 g and is 3.1-cm high for full-field high-resolution imaging of cerebral blood flow (CBF) in freely moving animals. Coherent laser light illuminates the cortex through a multimode optical fiber bundle fixed onto the supporting frame of the imager. The reflected lights are then collected by a miniature macrolens system and imaged by a high-resolution CMOS camera at a high frame rate (50 fps). Using this miniature imager, we achieve high spatiotemporal resolution laser speckle contrast imaging of CBF in freely moving animals in real time.

Vibration Measurement and Data Analysis of a Spinning Shaft Using a Camera-Based Motion Analysis System

This paper presents the use of a camera-based 3D motion analysis system for non-contact dynamic testing of a highly flexible spinning vertical shaft. The camera system uses high-resolution CMOS cameras to measure instant geometry of the shaft when visible red digital LED strobes are synchronized to work at a speed between 0.1 to 2000 frames per second. Dynamically deformed geometries are obtained by tracing the three-dimensional instantaneous coordinates of markers adhered to the shaft’s outside surface and triangulation techniques for identifying markers’ coordinates. Numerical simulation and experimental results show that the use of camera-based motion analysis systems is feasible and accurate enough for dynamic experiments. For dynamics characterization, we present the use of the Hilbert-Huang transform (HHT) for time frequency analysis of measured dynamic responses. The results show that the third-mode vibration has a cubic nonlinearity.

Abstract 1515: Regional Effects of Katp Channel Openers Reflect Distinct Atrial and Ventricular Katp Channel Structure in the Murine Heart

Classically, cardiac sarcolemmal KATP channels are thought to be composed of Kir6.2 (inward-rectifier potassium channel 6.2, KCNJ11) and SUR2A (sulfonylurea receptor type 2A, ABCC9) subunits. However, the evidence is strong that SUR1 (sulfonylurea receptor type 1, ABCC8) subunits are also expressed in the heart and that they play a significant functional role in the atria. To examine this further, we have estimated the effects of potassium channel-opening drugs diazoxide (specific to SUR1 > SUR2A) and pinacidil (SUR2A > SUR1) in intact hearts from wild type (WT, n=6) and SUR1−/− mice (KO, n=3) that lack SUR1 subunits. Action potential duration (APD) in both atria and ventricles were estimated by optical mapping of posterior surface of Langendorff-perfused hearts using the voltage sensitive dye RH237 and high spatiotemporal resolution CMOS camera (100x100 pixels; 3,000 frames/sec). In WT hearts, diazoxide (300 μM) decreased APD in atria (from 33.6±2.1 ms to 25.5±1.0 ms, p<0.001) and did not change it in ventricles (60.0±8.5 ms vs 61.2±8.3 ms, NS). The absence of SUR1 in KO mice resulted in loss of efficacy of diazoxide in atria (37.5±0.7 ms vs 36.5±0.7 ms, NS). In contrast, pinacidil (300 μM) significantly decreased ventricular APD in both type of mice (from 60.0±8.5 ms to 30.5±4.2 ms in WT, p<0.001; and from 62.0±1.4 ms to 30.5±6.4 ms in KO, p<0.001) and did not change atrial APD in either WT or KO hearts. Glass microelectrode recordings from isolated superfused atria confirmed the optical data. In both WT and KO hearts, the APD in left ventricle was significantly longer and the effect of pinacidil was significantly greater than in right ventricle (APD decreasing by 56.3±4.2% and 62.3±12.0% in left ventricle vs 49.4±3.4% and 50.9±4.1% in right ventricle for WT and KO mice respectively, p<0.05). Similar differences between APDs in right and left atria were not observed. Collectively, these results indicate that in the intact mouse heart, significant differential KATP pharmacology in atria and ventricles results from SUR1 predominance in forming the atrial channel, highlighting an unappreciated heterogeneity of KATP function in the heart.