Abstract:
The invention provides nanoparticles comprising one or more redox-active species, methods of making such nanoparticles , and methods for using such nanoparticles , for example, as diagnostic agents for the detection of various analytes.
Abstract:
A method of measuring calcium ions is disclosed wherein a calcium sensitive reagent, calcichrome, is immobilized on a porous polymer film. The reaction of the calcium sensitive reagent to the Ca(II) is then measured and concentration determined as a function of the reaction.
Abstract:
An acoustic wave based-chemical sensor containing a crystal substrate and a coating of small particulate matter is disclosed. The small particulate matter can be graphite particles. Transducers are connected to the crystal substrate to generate an alternating potential across the crystal substrate, which in turn causes the crystal to resonate due to the converse piezoelectric effect. The coating absorbs the analyte, thus changing the mass of the sensor, and accordingly changing its resonant frequency. The transducers detect this change in resonant frequency to indicate that the analyte is present. The use of small particulate matter results in a coating having a large surface area which facilitates mass uptake of large amounts of VOCs, improved acoustic properties even with relatively thick coatings, and a high operational temperature range.
Abstract:
A method and apparatus for chromatographic separations comprising a conductive-polymer stationary phase for controlled interaction with ionic species. The conductive polymer stationary phase is held at an initial voltage while analyte containing ionic species is added. The ionic species interact with and are held by the stationary phase. Voltage across the stationary phase is varied by linear or step waveforms which alters the stationary phase charge characteristics. Ionic species are selectively released from the stationary phase as its charge characteristics change due to the individual charges of each ionic species. Ionic species released from the stationary phase are flushed from the column by an ionic mobile phase.
Abstract:
A dual wavelength optical sensor for measuring the optical characteristics of sensing films which are responsive to a particular quantity to be measured. The optical sensor includes a light source (16, 18) for producing light outputs at two distinct wavelengths and transmitting twin components of light to first and second outputs. A time-shared optical fiber (26) receives the two distinct wavelengths of light from the first output and carries the light on a time-shared basis to a sensor probe (14). A sample detector (30) receives the two distinct wavelengths of light transmitted from the thin sensing film. A reference detector (34) receives the two distinct wavelengths of light from the second output and monitors the output intensity of the light source. A signal processing system (35) combines the measurements of the optical characteristics of the thin sensing film in response to each of the two distinct wavelengths to provide measurements which account for changes in the optical properties of the thin sensing film.
Abstract:
Capteur optique à double longueur d'onde servant à mesurer les caractéristiques optiques des couches détectrices sensibles à une certaine grandeur à mesurer. Le capteur comprend une source lumineuse (16, 18) produisant des sorties lumineuses ayant deux longueurs d'onde distinctes, et émettant une paire de composantes lumineuses vers une première et une seconde sortie. Une fibre optique exploitée en temps partagé (26) reçoit la lumière ayant deux longueurs d'ondes distinctes et étant émise par la première sortie, et transmet cette lumière, dans des conditions d'exploitation en temps partagé, à une sonde détectrice (14). Un détecteur d'échantillonnage (30) reçoit la lumière ayant deux longueurs d'ondes distinctes et étant émise par la couche mince détectrice. Un détecteur de référence (34) reçoit la lumière ayant deux longueurs d'ondes distinctes et étant émise par la seconde sortie, et contrôle l'intensité à la sortie de la source lumineuse. Un système de traitement de signaux (35) associe les unes aux autres les mesures des caractéristiques optiques de la couche mince détectrice en réponse à chacune des deux longueurs d'ondes distinctes, afin de produire des mesures exprimant les variations des caractéristiques optiques de la couche mince détectrice.