The present invention, in some embodiments thereof, relates to detection of a substance and, more particularly, but not exclusively, to a system and method for detecting a substance in liquid.
The development of miniaturized devices for chemical analysis and for synthesis and fluid manipulation is motivated by the prospects of improved efficiency, reduced cost and enhanced accuracy. Efficient, reliable manufacturing processes are a critical requirement for the cost-effective, high-volume production of devices that are targeted at high-volume, high-throughput test markets.
Microfluidic devices include components such as channels, reservoirs, mixers, pumps, valves, chambers, cavities, reaction chambers, heaters, fluidic interconnects, diffusers, nozzles, and other microfluidic components. These microfluidic components typically have dimensions which range between several micrometers to several millimeters. The small dimensions of such components minimize the physical size, the power consumption, the response time and the waste of a microfluidic device as compared to other technologies.
Several attempts have been made to incorporate biological materials as biosensors capable of sensing physical or chemical environmental conditions in microfluidic devices.
Generally, a biosensor is a device that qualifies and/or quantifies a physiological or biochemical signal. Biosensors have been developed to overcome some of the shortcomings of the classical agent detection techniques. Good biosensing systems are characterized by specificity, sensitivity, reliability, portability, ability to function even in optically opaque solutions, real-time analysis and simplicity of operation. Biosensors couple a biological component with an electronic transducer and thus enable conversion of a biochemical signal into a quantifiable electrical response.
The function of the biosensor depends on the biochemical specificity of the biologically active material. Enzymes, antibodies, aptamers, DNA, receptors, organelles and microorganisms as well as plant cells or tissues have been used as biological sensing elements. The most commonly used biological element in the construction of biosensors are enzymes, due to their high specific activities as well as high analytical specificity. Purified enzymes are, however, expensive and unstable, thus limiting their applications in the field of biosensors.
Following are technologies incorporating biosensors in microfluidic devices.
U.S. Pat. No. 6,436,698 is directed at automatic measurement of water toxicity, using luminescent microorganisms living in freshwater. Test samples are injected using a needle into multi-well plate containing the luminescent microorganisms and, after a lapse of certain times from the injection, luminosity is detected by a sensor.
U.S. Pat. No. 6,117,643 is directed at detection of pollutants, explosives and heavy-metals. A bioreporter, capable of metabolizing a particular substance to emit light, is placed in a selectively permeable container. When the light is emitted, an optical application specific integrated circuit generates an electrical signal which indicates the concentration of the substance.
U.S. Pat. No. 6,133,046 teaches the use of a fixed electrode and a moving electrode, whereby the surfaces of the electrodes bound a ligand of the agent to be detected (e.g., an antibody, whereby the agent is an antigen or a hapten, a receptor whereby the agent is a receptor, etc.). When a sample is placed between the electrodes, an electric signal is generated, depending on whether or not the agent is present.
U.S. Published Application No. 20080044844 discloses a device for detecting presence, absence or level of an analyte in a sample. The device includes a substrate configured for supporting a population of cells in an addressable manner so as to allow identification of each discrete subpopulation of cells. The surface of the substrate is fabricated with discrete microwells configured to enable holding the subpopulations of the cells. Microchannels provide fluid communication between the microwells and sample ports.
U.S. Published Application No. 200800448 discloses a population of cells comprising at least two subpopulations of cells, wherein a first subpopulation of the at least two subpopulation of cells includes a first reporter expression construct being expressible in a cell of the first subpopulation when exposed to a first analyte and whereas a second subpopulation of the at least two subpopulation of cells includes a second reporter expression construct being expressible in a cell of the second subpopulation when exposed to a second analyte.
Additional background art includes: U.S. Pat. Nos. 6,638,752, 6,638,483, 6,636,752, 6,632,619, 6,627,433, 6,630,353, 6,620,625, 6,544,729, 6,537,498, 6,521,188, 6,453,928, 6,448,064, 6,340,572, 6,377,721 and 5,922,537, Ben-Yoav et al., 2008, ECS Trans., Volume 16, Issue 11, Microfabrication and Microfluidics, pages 187-197, Vollmer et al. Applied and Environmental Microbiology 63(7) (1997) 2566-2571 and X. Xiaorong, M. E. Lidstrom, B. A. Parviz, J. Microelectromech. Syst. 16(2) (2007) 429-444.