Arthur Rabner

Whole-cell luminescence biosensor-based lab-on-chip integrated system for water toxicity analysis

A novel water chemical toxin sensor has been successfully developed and evaluated as a working portable laboratory prototype. This sensor relies on a disposable plastic biochip prepared with a 4x4 micro-laboratory (μLab) chambers array of Escherichia coli reporter cells and micro-fluidic channels for liquids translocation. Each bacterial strain has been genetically modified into a bioluminescent reporter that responds to a pre-determined class of chemical agents. When challenged with a water sample containing a toxic chemical, the sensor responds with an increased bioluminescent signal from the biochip that is monitored over time. The signal is received by a motorized photomultiplier-based analyzer and interpreted by signal processing software. We have performed several levels of analysis: (i) the change in the bioluminescent signal from the sensor bacteria serves as a rapid indication for the presence of toxic chemicals in the water sample; (ii) the intensity of the change indicates the toxin concentration level; and (iii) the pattern of the responses for the different members of the bacterial panel on the biochip characterizes the biological origin of the toxin. The analyzer contains housing mechanics, electro-optics for signal acquisition, motorized readout calibration accessories, hydro-pneumatics modules for water sample translocation into biochip micro laboratories, electronics for overall control and communication with the host computer. This prototype has a demonstrated sensitivity for broad classes of water-borne toxic chemicals including naladixic acid (a model genotoxic agent), botulinum and acetylcholine esterase inhibitors. This work has initiated an investigation of a novel handheld field-deployable Water Toxicity Analysis (WTA) device.

Electron-Bombarded CMOS Image Sensor in Single Photon Imaging Mode

Solid-state devices utilizing “photonic events amplification” (PEA) are used for low-level light imaging (LLLI) and are exploited in military, scientific, astronomy, surveillance, and other applications. The PEA imagers are more sensitive by a few orders of magnitude than regular CCD cameras and by an order of magnitude than most sensitive scientific LLLI CCD cameras. The Electron-Bombarded CMOS Image Sensor (EB-CMOS-IS) is a novel PEA technology and has just recently become commercially available. The EB-CMOS-IS technology is a best price/performance combination among concurrent technologies such as EBCCD, EMCCD, Intensified CCD, and Intensified CMOS image sensors. Although the EB-CMOS-IS-based applications demonstrate outstanding sensitivity, they are exploited today far from their maximal potential. In this study, we developed a comprehensive model of the EB-CMOS-IS used for simulation of the sensor performance as a function of the device parameters, e.g., photocathode quantum efficiency, acceleration bias, electrons-to-voltage conversion factor, and operation parameters, e.g., amplifier gain, offset, and exposure time. We selected parameters enabling a single photon imaging (SPI) mode and performed imaging simulations for an object under various low-level illumination conditions. We present a method of the EB-CMOS-IS operation in the SPI mode for low-light-level imaging of a stationary object, boosting the sensor sensitivity to a level better than 10-7 lux.

A Concept for a Sensitive Micro Total Analysis System for High Throughput Fluorescence Imaging

This paper discusses possible methods for on-chip fluorescent imaging forintegrated bio-sensors. The integration of optical and electro-optical accessories, accordingto suggested methods, can improve the performance of fluorescence imaging. It can boostthe signal to background ratio by a few orders of magnitudes in comparison to conventionaldiscrete setups. The methods that are present in this paper are oriented towards buildingreproducible arrays for high-throughput micro total analysis systems (μTAS). The firstmethod relates to side illumination of the fluorescent material placed into micro-compartments of the lab-on-chip. Its significance is in high utilization of excitation energyfor low concentration of fluorescent material. The utilization of a transparent μLED chip,for the second method, allows the placement of the excitation light sources on the sameoptical axis with emission detector, such that the excitation and emission rays are directedcontroversly. The third method presents a spatial filtering of the excitation background.