Assay Apparatuses, Methods and Reagants

An instrument adapted to interrogate samples contained in a multi-well plate comprising:

• a carriage frame configured to support the multi-well plate and the carriage frame is movable relative to a contact platform,
• wherein the multi-well plate comprises a plurality of wells, wherein the wells are arranged in a M×N matrix, and
• wherein the contact platform comprises a plurality of interrogation zones, wherein each interrogation zone comprises at least a pair of electrical contacts to conduct a voltage potential to at least one well, and
• a controller operatively connected to a motor to move the carriage frame relative to the contact platform and operatively connected to a voltage source, wherein the voltage source is connectable to one or more pairs of electrical contacts, and
• a multiplexer connected to the controller and to the voltage source for selectively connecting the voltage source to the pair of electrical contacts of a single interrogation zone or connecting the voltage source to at least one pair of electrical contacts of more than one interrogation zones.

A focusing mechanism for an optical sensor comprising at least a higher, middle and lower patterned surface spaced apart from the optical sensor;

• wherein the middle patterned surface is aligned to a target surface to be focused by the optical sensor and the middle patterned surface
• wherein a first distance between the higher and middle patterned surfaces and a second distance between the middle surface and lower patterned surface are substantially equal,
• wherein the optical sensor and the patterned surfaces are moved relative to each other until a difference between a first and a second contrast value difference is less than a predetermined value;
• and
• an illuminating source positioned to project light through the higher, middle and lowered patterned surfaces toward the optical sensor.

A method for focusing an optical sensor to a spaced apart platform comprising the steps of

• a. providing at least a higher, middle and lower patterned surface, wherein the middle patterned surface and the platform are aligned to each other and wherein a first distance between the higher and middle patterned surfaces and a second distance between the middle surface and lower patterned surface are substantially equal;
• b. obtaining a first contrast value difference between the higher and middle patterned surfaces with the optical sensor;
• c. obtaining a second contrast value difference between the middle and lower patterned surfaces with the optical sensor;
• d. comparing the first and second contrast value differences.