5426results about "Analysis using chemical indicators" patented technology

The present invention provides novel microfluidic substrates and methods that are useful for performing biological, chemical and diagnostic assays. The substrates can include a plurality of electrically addressable, channel bearing fluidic modules integrally arranged such that a continuous channel is provided for flow of immiscible fluids.

An analytical test device useful for example in pregnancy testing, comprises a hollow casing (500) constructed of moisture-impervious solid material, such as plastics materials, containing a dry porous carrier (510) which communicates indirectly with the exterior of the casing via a bibulous sample receiving member (506) which protrudes from the casing such that a liquid test sample can be applied to the receiving member and permeate therefrom to the porous carrier, the carrier containing in a first zone a labelled specific binding reagent is freely mobile within the porous carrier when in the moist state, and in a second zone spatially distinct from the first zone unlabelled specific binding reagent for the same analyte which unlabelled reagent is permanently immobilized on the carrier material and is therefore not mobile in the moist state, the two zones being arranged such that liquid sample applied to the porous carrier can permeate via the first zone into the second zone, and the device incorporating means, such as an aperture (508) in the casing, enabling the extent (if any) to which the labelled reagent becomes bound in the second zone to be observed. Preferably the device includes a removable cap for the protruding bibulous member.

The present invention provides a method of measuring an analyte, such as glucose in a fluid sample, such as whole blood, by a reflectance reading device. The method includes making periodic intermediate calculations of analyte level and dynamically ascertaining when an analytical reaction has reached an end point. Once stable, the process stops making periodic calculations and reports the final, actual glucose concentration. According to an exemplary embodiment, the method is performed by a reflectance photometer using an analytical test strip containing reagents that react with an analyte of interest in the test fluid. The end point is determined by calculating an intermediate analyte level of the testing element at predetermined intervals and calculating a ratio value corresponding to the (n)th measurement to an (n-5)th measurement. When two consecutive ratio values are less than or equal to a predetermined value, the end point is deemed reached and the final analyte level ascertained.

Methods for high speed, high throughput analysis of polynucleotide sequences, and apparatuses with which to carry out the methods are provided in the invention.

A test strip with a covering layer having a novel slot. The slot divides the inventive covering layer into two parts and provides a vent opening that allows air to escape as fluid enters a cavity or sample receiving chamber formed in the test strip. In preferred embodiments, the covering layer is clear such that the user can see through it and the slot doubles as a “fill line.” The user can thus watch the fluid sample enter the test strip, progress through the capillary cavity, and then stop at the slot or fill-line. This provides positive assurance to the user that the sample size is sufficient and the test strip has been filled properly. The present invention also provides an advantageous method of mass-producing the inventive test strips without having to align the slot or vent opening laterally with respect to the test strips and without having to punch a vent opening. The method is also well suited to mass production by roll processing techniques.

A method of measuring an analyte in a biological fluid comprises applying an excitation signal having a DC component and an AC component. The AC and DC responses are measured; a corrected DC response is determined using the AC response; and a concentration of the analyte is determined based upon the corrected DC response. Other methods and devices are disclosed.

The present invention provides microfluidic technology enabling rapid and economical manipulation of reactions on the femtoliter to microliter scale.