Abstract
The needle-type dispenser using a thin needle and a glass capillary with a sample liquid has been developed for micro-droplet application. Pico-liter order droplets can be dispensed from high-viscosity liquids by the needle-type dispenser. However, a gap between the needle tip and the target surface is formed when a micro droplet is dispensed. Volumes of droplets are unstable, as the dispensing gaps are fluctuated. A contact-detection method of the needle-tip droplet and the target surface is proposed to keep a dispensing gap constant. The needle is vibrated by a piezoelectric actuator through a leaf spring in the proposed method. Needle-vibration characteristics of spring-mass-damper model are variable by conditions between the needle-tip droplet and the target surface. In this report, the proposed method for contact detection is evaluated in the experiments.
