Liquid and plate sensors for microplate injector system

A sample analyzing apparatus, comprising:

• an apparatus housing;
• a sample carrier disposed in the apparatus housing and configured for supporting a sample;
• a reservoir support configured for supporting a reagent reservoir;
• a pump configured for communicating with the reagent reservoir;
• an injector assembly disposed in the apparatus housing, and comprising an injector housing and an injector needle extending through the injector housing and configured for communicating with the reagent reservoir via the pump;
• a driver configured for moving the injector assembly toward and away from the sample carrier;
• and
• a luminescence detector positioned in the apparatus housing to receive optical signals from the sample, wherein:
• the injector housing comprises a distal housing end, the injector needle comprises a needle outlet at the distal housing end, and the injector assembly comprises a liquid sensor disposed in the injector housing and configured for detecting liquid at the housing end;
• and
• the injector assembly has a configuration selected from the group consisting of:
• the liquid sensor comprises a first wire electrically coupled to the injector needle at or proximate to the needle outlet, and a second wire electrically coupled to the injector housing at or proximate to the distal housing end, wherein the first wire and the second wire are configured for communicating with electronics configured for detecting an electrical current between the injector needle and the injector housing;
• the liquid sensor comprises an electrical contact positioned at the same or substantially the same elevation as the needle outlet, a first wire electrically coupled to the electrical contact, and a second wire electrically coupled to the injector needle at or proximate to the needle outlet or to the injector housing at or proximate to the distal housing end, wherein the first wire and the second wire are configured for communicating with electronics configured for detecting an electrical current between the electrical contact and the injector needle or between the electrical contact and the injector housing;
• the injector needle is a first injector needle, the needle outlet is a first needle outlet, and the injector assembly further comprises a second injector needle extending through the injector housing comprising a second needle outlet, and the liquid sensor comprises a first wire electrically coupled to the first injector needle at or proximate to the first needle outlet, and a second wire electrically coupled to the second injector needle at or proximate to the second needle outlet, wherein the first wire and the second wire are configured for communicating with electronics configured for detecting an electrical current between the first injector needle and the second injector needle;
• and
• the liquid sensor comprises an electrically conductive tube configured for communicating with electronics configured for detecting an electrical current between the electrically conductive tube and the injector needle or between the electrically conductive tube and the injector housing.