Western blotting electrophoretic sequencing is an analytical technique widely used in Functional Proteomics
to detect, recognize and quantify specific labelled proteins in biological samples. A commonly used label
for western blotting is Enhanced ChemiLuminescence (ECL) reagents based on fluorescent light emission of
Luminol at 425nm. Film emulsion is the conventional detection medium, but is characterized by non-linear
response and limited dynamic range. Several western blotting digital imaging systems have being developed,
mainly based on the use of cooled Charge Coupled Devices (CCDs) and single avalanche diodes that address
these issues. Even so these systems present key drawbacks, such as a low frame rate and require operation at
low temperature. Direct optical detection using Complementary Metal Oxide Semiconductor (CMOS) Active
Pixel Sensors (APS)could represent a suitable digital alternative for this application. In this paper the authors
demonstrate the viability of direct chemiluminescent light detection in western blotting electrophoresis using a
CMOS APS at room temperature. Furthermore, in recent years, improvements in fabrication techniques have
made available reliable processes for very large imagers, which can be now scaled up to wafer size, allowing
direct contact imaging of full size western blotting samples. We propose using a novel wafer scale APS (12.8
cm×13.2 cm), with an array architecture using two different pixel geometries that can deliver an inherently low
noise and high dynamic range image at the same time representing a dramatic improvement with respect to
the current western blotting imaging systems.
X-ray diffraction studies are used to identify specific materials. Several laboratory-based x-ray diffraction studies were
made for breast cancer diagnosis. Ideally a large area, low noise, linear and wide dynamic range digital x-ray detector is
required to perform x-ray diffraction measurements. Recently, digital detectors based on Complementary Metal-Oxide-
Semiconductor (CMOS) Active Pixel Sensor (APS) technology have been used in x-ray diffraction studies. Two APS
detectors, namely Vanilla and Large Area Sensor (LAS), were developed by the Multidimensional Integrated Intelligent
Imaging (MI-3) consortium to cover a range of scientific applications including x-ray diffraction. The MI-3 Plus
consortium developed a novel large area APS, named as Dynamically Adjustable Medical Imaging Technology
(DynAMITe), to combine the key characteristics of Vanilla and LAS with a number of extra features. The active area
(12.8 × 13.1 cm2) of DynaMITe offers the ability of angle dispersive x-ray diffraction (ADXRD). The current study
demonstrates the feasibility of using DynaMITe for breast cancer diagnosis by identifying six breast-equivalent plastics.
Further work will be done to optimize the system in order to perform ADXRD for identification of suspicious areas of
breast tissue following a conventional mammogram taken with the same sensor.
KEYWORDS: Sensors, Signal to noise ratio, High dynamic range imaging, Image sensors, CMOS sensors, Signal detection, Interference (communication), Transistors, Active sensors, Double positive medium
A new pixel structure for high dynamic range imaging is proposed. The internal pixel circuit resets the pixel each
time the well capacity nears saturation and a counter, implemented in the pixel itself (or in an external memory),
records the number of resets per integration time. The increase in the dynamic range is given by a factor of (m + 1)
where m is the number of internal resets per integration time. The peak signal-to-noise ratio will be increased due to
the effective increase in the well capacity. A multiple sampling technique can be used in the combination with this
proposed structure to achieve a further increase in dynamic range.
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