Sample analysis systems, devices, and associated methods of operation

A method of analyzing a sample containing an electrolyte, comprising:

• sequentially introducing a leading electrolyte, a sample electrolyte, and a trailing electrolyte into a extraction channel carried by a substrate, the extraction channel having a constriction in cross-sectional area;
• applying an electrical field to separate components of the sample electrolyte into stacks and to concentrate the separated components by forcing the sample electrolyte to migrate through the constriction in the extraction channel;
• and
• thereafter, removing the applied electrical field and detecting the separated and concentrated components of the sample in a detection channel carried by the substrate, wherein the detection channel includes a detection site, and wherein the method further includes attaching at least one of the separated and concentrated components to the detection site.

A method of measuring cardiac troponin I (cTnI) concentration, comprising:

• loading an extraction channel on a substrate with a leading electrolyte, a sample containing cTnI, and a trailing electrolyte in sequence between a first end and a second end of the channel;
• applying an electrical field between the first and second ends of the channel;
• with the applied electrical field, separating phosphorylated and unphosphorylated cTnI components into stacks under isotachophoresis while forcing the sample to migrate through a constriction in the extraction channel;
• detecting the separated phosphorylated and unphosphorylated cTnI components in a detection channel on the substrate and in fluid communication with the extraction channel;
• monitoring a formation of the stacks in the extraction channel;
• and
• removing the applied electrical field after the stacks are substantially constant.