A nanosensor for detecting molecule characteristics includes a membrane having an opening configured to permit a charged carbon nanotube to pass but to block a molecule attached to the carbon nanotube. The opening is filled with an electrolytic solution. An electric field generator is configured to generate an electric field relative to the opening to drive the charged carbon nanotubes through the opening. A sensor circuit is coupled to the electric field generator to sense current changes due to charged carbon nanotubes passing into the opening, and to bias the electric field generator to determine a critical voltage related to a force of separation between the carbon nanotube and the molecule.

A method of transmitting at least one optical signal through an add-drop filter includes directing the at least one optical signal into a first tapered optical fiber of the add-drop filter. The add-drop filter includes an active resonator side-coupled between the first tapered optical fiber and a second tapered optical fiber, and the active resonator is doped with at least one rare earth ion. A tuned optical gain is produced by delivering a tuned amount of pump laser energy to the at least one rare earth ion at a sub-lasing level, the tuned optical gain configured to compensate an intrinsic loss of the active resonator.

Random arrays of single molecules are provided for carrying out large scale analyzes, particularly of biomolecules, such as genomic DNA, cDNAs, proteins, and the like. In one aspect, arrays of the invention comprise concatemers of DNA fragments that are randomly disposed on a regular array of discrete spaced apart regions, such that substantially all such regions contain no more than a single concatemer. Preferably, such regions have areas substantially less than 1 m.sup.2 and have nearest neighbor distances that permit optical resolution of on the order of 10.sup.9 single molecules per cm.sup.2. Many analytical chemistries can be applied to random arrays of the invention, including sequencing by hybridization chemistries, sequencing by synthesis chemistries, SNP detection chemistries, and the like, to greatly expand the scale and potential applications of such techniques.

Random arrays of single molecules are provided for carrying out large scale analyzes, particularly of biomolecules, such as genomic DNA, cDNAs, proteins, and the like. In one aspect, arrays of the invention comprise concatemers of DNA fragments that are randomly disposed on a regular array of discrete spaced apart regions, such that substantially all such regions contain no more than a single concatemer. Preferably, such regions have areas substantially less than 1 m.sup.2 and have nearest neighbor distances that permit optical resolution of on the order of 10.sup.9 single molecules per cm.sup.2. Many analytical chemistries can be applied to random arrays of the invention, including sequencing by hybridization chemistries, sequencing by synthesis chemistries, SNP detection chemistries, and the like, to greatly expand the scale and potential applications of such techniques.

This disclosure provides technology for ordering sequence information derived from one or more target polynucleotides. In one aspect, one or more tiers or levels of fragmentation and aliquoting are generated, after which sequence information is obtained from fragments in a final level or tier. Each fragment in such final tier is from a particular aliquot, which, in turn, is from a particular aliquot of a prior tier, and so on. For every fragment of an aliquot in the final tier, the aliquots from which it was derived at every prior tier is known, or can be discerned. Thus, identical sequences from overlapping fragments from different aliquots can be distinguished and grouped as being derived from the same or different fragments from prior tiers. When the fragments in the final tier are sequenced, overlapping sequence regions of fragments in different aliquots are used to register the fragments so that non-overlapping regions are ordered. In one aspect, this process is carried out in a hierarchical fashion until the one or more target polynucleotides are characterized, e.g. by their nucleic acid sequences, or by an ordering of sequence segments, or by an ordering of single nucleotide polymorphisms (SNPs), or the like.