A pipette device adapted to removably mount a tip at its lower end and having a housing in which there are provided a cylinder chamber communicating with the interior of the mounted tip, a plunger adapted to operate in the cylinder chamber for sucking a liquid and then discharging the same, a direct...http://www.google.com.hk/patents/US4399712?utm_source=gb-gplus-share專利 US4399712 - Semi-automatic electro-mechanical pipette with controlled tip remover
