Ultra-sensitive detection of molecules or particles using beads or other capture objects

A method for determining a measure of the concentration of analyte molecules or particles in a fluid sample, comprising:

• providing a substrate comprising a plurality of locations, at least a portion of which contain a bead, wherein with respect to the total number of beads present on the substrate, the ratio of beads comprising at least one analyte molecule or particle associated with a binding ligand to beads comprising no analyte molecules or particles associated with a binding ligand is between about 8:1 and about 1:10,000,000;
• addressing at least a portion of the plurality of locations, wherein during the addressing step at least two of the plurality of locations is addressed at least partially concurrently;
• detecting at each addressed location the presence or absence of a bead and whether, if present, the bead comprises any analyte molecules or particles associated with a binding ligand;
• and
• determining a measure of the concentration of analyte molecules or particles in the fluid sample at least in part by determining the number of locations addressed containing a bead comprising at least one analyte molecule or particle associated with a binding ligand.

A method for determining a measure of the concentration of analyte molecules or particles in a fluid sample, comprising:

• immobilizing a plurality of analyte molecules or particles with respect to a plurality of beads;
• spatially segregating at least a portion of the plurality of beads into a plurality of separate locations;
• addressing at least some of the plurality of locations and determining the number of locations containing a bead;
• further determining the number of said locations containing a bead and an analyte molecule or particle;
• and
• determining a measure of the concentration of analyte molecules or particles in the fluid sample based at least in part on the ratio of the number of locations containing a bead and an analyte molecule and particle, to the number of locations containing a bead.

A method for determining a measure of the concentration of analyte molecules or particles in a fluid sample, comprising:

• immobilizing a plurality of analyte molecules or particles with respect to a plurality of beads;
• spatially segregating at least a portion of the plurality of beads into a plurality of separate locations;
• addressing at least some of the plurality of locations and determining the number of locations containing a bead;
• further determining the number of said locations containing a bead and an analyte molecule or particle;
• and
• determining a measure of the concentration of analyte molecules or particles in the fluid sample based at least in part on the ratio of the number of locations containing a bead and an analyte molecule and particle, to the number of locations containing a bead but not containing any analyte molecules or particles.