The electrochemiluminescence (ECL) of Ru(bpy)<sub>3</sub><sup>2+</sup> (bpy = 2,2'-bipyridine and its derivatives) complexes has attracted interest from chem- and bio-analytical researchers. Particularly, by labeling bio-molecules with Ru(bpy)<sub>3</sub><sup>2+</sup> derivatives, highly competitive ECL immunoassay and DNA probing have been employed in clinical and research laboratories and are now becoming standard methods. In the well-established commercial systems designed for bench-top applications, paramagnetic microbeads are used for capturing the analytes and separating the excess of labeled biomolecules from the flow cell. The large surface area of the beads provides a high capacity and efficiency for analyte capturing. However, the use of microbeads prevents the instrument from being miniaturized. Furthermore, only a tiny portion of species is enabled to generate luminescence because of the inaccessibility of the majority of the labels to the electrode surface. We propose to develop a handheld device with disposable chips based on the ECL signal modality. Central to this instrumentation is the fabrication of a nanostructured electrode with spatially selective bioimmobilization. The electrode surface is structured to reach the maximum capturing ability and, at the same time, maintain the effective electroactive region and the accessibility for the ruthenium label to be excited electrochemically. In this presentation, we present a manufacturable approach to the fabrication of such disposable nanostructured electrodes for ECL-based handheld devices.
The secure information retrieval technologies are critical for status identification, particularly in the battlefield for friend/enemy discrimination. The materials or devices used in these technologies should be hard to find, difficult to counterfeit and as simple as possible. Moreover, if the coding information is totally position-invariant, i.e. neither sequence nor pixel based, it will greatly simplify the retrieval system. We describe an information retrieval technology, which possesses the above-mentioned features. The information is encoded by using luminescent semiconductor nanocrystals (or quantum-dots, QDs) mixed with a transparent solution, namely info-ink. When an exciting light beam shines at the info-ink, its emitting spectral features, i.e., wavelength and intensity, provide the encoded information. The info-ink could be applied on any kind of surface, for examples, document cover, top area of helmet, and even a fingernail. It is actually a thin layer of paint and requires no power supply. The retrieval device consists of an exciting light source, a mini-spectrometer and a data processing unit. However, for battlefield applications, a major problem with fluorescence-based technology is that the brightness of sunlight can overwhelm most reflected fluorescent signal. To overcome the shortcomings, the quantum dots are engineered to fluoresce at wavelengths corresponding to the absorption lines of the solar spectrum, more commonly known as Fraunhofer lines.
With fiber optical telecommunication systems penetrating into metropolitan and access networks, planar waveguide technology is increasingly being considered a solution to the bottleneck of cost-effective manufacture of passive components. Being recognized for their high thermo-optical coefficient, ease of fabrication, cost-effectiveness, good compatibility with other materials, polymer as a platform technology for waveguide devices is gaining more and more commercial acceptance. Fully exploiting the potentials of the polymeric materials demands comprehensive understanding of both the specific device applications and various polymer systems. The right choice of materials is often the key to the success of component development. Unfortunately, since extensive study on polymeric materials and devices operating at 1.55 micrometer just began recently, few ideal materials have been so far made commercially available. From the polymer chemistry point of view, it is possible to tailor the materials meeting specific and strict requirements for optical waveguide devices. The present author reviews the most promising fluorinated polymers and silicone resins and their demonstrated device applications. The paper is designed for providing guide to both polymer scientists, who want to develop novel high performance materials for waveguide applications, and optical engineers who need to gain insight of the materials.
A possible method for WIMPs detection using liquid xenon scintillation is discussed. Background from cosmic and radioactive gamma rays at energies down to the keV region can be easily rejected by requiring the presence of proportional scintillation. The results from a basic test are presented and a prototype detector design is proposed.
Recent operation results of a three-ton liquid argon time projection chamber for the ICARUS project are reported. This elecronic continually sensitive, self-triggering bubble-chamber is capable of providing 3D imaging of any ionizing event in conjunction with a good calorimetric response.