MICROVOLUME LIQUID HANDLING SYSTEM

摘要

A microvolume liquid handling system includes a microdispenser employing a piezoelectric transducer attached to a glass capillary, a positive displacement pump for priming and aspirating transfer liquid into the microdispenser, controlling the pressure of the liquid system, and washing the microdispenser between liquid transfers, and a pressure sensor to measure the liquid system pressure and produce a corresponding electrical signal. The pressure signal is used to verify and quantify the microvolume of transfer liquid dispensed and is used to perform automated calibration and diagnostics on the microdispenser. In another embodiment of the microvolume liquid handling system, a system reservoir is connected with tubing to a pressure control system for controlling the liquid system pressure in the system reservoir. The system reservoir is coupled to one or more microdispensers through a distribution tube having a branched section for each microdispenser. In this embodiment, each microdispenser is coupled to its own flow sensor and to enable a system controller to respectively measure and control the flow of liquid in the each microdispenser. Dispensing of a single sub-nanoliter drop can be detected in real time. As the result of dispensing the liquid in sub-nanoliter droplets, the dispensed volume can be precisely controlled. The dispenser automatically detects the liquid surface of the transfer liquid, automatically aspirate, analyze desired volume of the transfer liquid, dispense the transfer liquid without contacting the destination vessel or its contents, and automatically wash off the transfer liquid from dispensing system after each transfer. This system is capable of automatically sensing liquid surfaces, aspirating liquid to be transferred, and then dispensing small quantities of liquid with high accuracy, speed and precision. The system is pulsated at high frequency to prevent or eliminate clogging. Immiscible liquid between the transfer liquid and the system liquid reduces the required amount of transfer liquid needed for dispensing.