Methods, systems, and computer program products for detecting a droplet

A method for operating a pipette comprising:

• providing a pipette including a pipette pressure detector that measures pressure at an internal portion of the pipette;
• positioning the pipette at a distance above a surface;
• dispensing a fluid from a pipette tip attached to the pipette;
• measuring pipette pressure in real-time at the internal portion of the pipette at given sampling time intervals during the step of dispensing the fluid from the pipette tip to generate a plurality of pipette pressure values;
• determining a plurality of pressure differences, wherein the step of determining the plurality of pressure differences comprises calculating the difference between at least one previously measured pipette pressure value and a most recently measured pipette pressure value;
• estimating a plurality of rate of change in pipette pressure values during a given time interval, wherein the step of estimating the plurality of rate of change in pipette pressure values during the given time interval comprises multiplying a most recently determined pressure difference by a weighting factor to give a weighted pressure difference and summing the weighted pressure difference with a weighted previously calculated pressure difference to provide a rate of change in pipette pressure, and comparing the rate of change in pipette pressure to an upper pressure related threshold and a lower pressure related threshold;
• detecting formation of the droplet at a distal end of the pipette tip when at least one of the plurality of rate of change in pipette pressure values is greater than or equal to the upper pressure related threshold and another one of the plurality of rate of change in pipette pressure values is less than or equal to the lower pressure related threshold;
• and
• stopping the dispensing of the fluid from the pipette tip when the droplet is detected or moving the pipette when the droplet is detected.