Device for detecting leading end of pipette tip, and storage medium storing program for detecting leading end of pipette tip

A pipette tip leading end detection device for detecting that a leading end of a pipette tip attached to a pipette nozzle and sucking or discharging liquid is close to a reference surface set to a reaction vessel having an accommodation part capable of accommodating the liquid, comprising:

• the pipette nozzle with the pipette tip attached thereto;
• a pump connected to the pipette nozzle;
• a nozzle driver that moves the pipette nozzle up and down,
• a pressure sensor that detects a pipette tip-pump pressure generated between the pipette tip and the pump;
• and
• a hardware processor that controls operations of at least the pump and the nozzle driver, wherein
• the hardware processor:
• obtains a determination value using an AD conversion value which is a value obtained by A/D converting the pipette tip-pump pressure detected by the pressure sensor while the pipette nozzle is being lowered towards a bottom surface of the accommodation part by the nozzle driver and air is being discharged or sucked from the leading end of the pipette tip by the pump;
• and
• detects that the leading end of the pipette tip is close to but not in contact with the bottom surface of the accommodation part as the reference surface on the basis that the obtained determination value is equal to or greater than a preset threshold value, wherein:
• the determination value is a calculation value indicating speed of a change in the pressure calculated by using a plurality of AD conversion values within a past certain time including a latest AD conversion value among AD conversion values of the pipette tip-pump pressure detected every certain time or consecutively;
• and
• the threshold value is a value larger than a maximum value of noise included in the determination value which occurs in the course of moving the leading end of the pipette tip towards the bottom surface of the accommodation part.