Dispensing device, dispensing method and method of detecting defective discharge of solution containing biological sample

A method of detecting a defective discharge of a solution containing a biological sample in a discharge mechanism for adjusting the pressure inside said pressurized chamber by mechanical displacement of an elastically deforming diaphragm, which is disposed so as to face an electrode substrate in a minute gap having a plurality of separate electrodes formed in correspondence with each of the plurality of pressurized chambers to be filled with a solution containing a biological sample, with the electrostatic force corresponding to the potential difference with said separate electrodes, and discharging said solution from a nozzle hole, comprising the steps of:

• applying, under the control of a drive voltage generator circuit connected between said diaphragm and said separate electrodes, a drive voltage of a prescribed waveform between said diaphragm and said separate electrodes in order to discharge said solution from said nozzle hole;
• detecting, under the control of a current detection circuit connected, separately from said drive voltage generation circuit, between said diaphragm and said separate electrodes, a current flowing between said diaphragm and separate electrodes during the period from the rising edge of the pulse of said drive voltage to the termination of discharge of the solution when said drive voltage is applied;
• and
• discriminating the existence of a defective discharge of the solution based on whether a peak waveform of a differential waveform of the current detected during the period appears on the positive side two consecutive times.