Abstract: There is provided a liquid droplet monitoring and measuring apparatus (1) for a liquid droplet dispensing system having a nozzle (5) with a dispensing tip (7). The apparatus (1) comprises an inner chamber (2) surrounded by an outer shield (3), preferably not in contact with each other. An RF oscillator electrically energizes the liquid through an electrode (11). The inner chamber (2) is connected through pre-amplifiers (16), band pass filters (17conditioning amplifier (20) to a signal read-out device (21). The operation of the apparatus is based on the measurement of the capacitance between the nozzle (5) and the inner chamber (2). As a droplet (15) grows on the dispensing tip (7), the capacitance between the nozzle (5) and the inner chamber (2) increases. Therefore, the signal detected and received by the signal read-out device (21) changes. This change is directly related to the volume of the droplet which can therefore be measured.

Abstract: There is provided a liquid droplet monitoring and measuring apparatus (1) for a liquid droplet dispensing system having a nozzle (5) with a dispensing tip (7). The apparatus (1) comprises an inner chamber (2) surrounded by an outer shield (3), preferably not in contact with each other. An RF oscillator electrically energises the liquid through an electrode (11). The inner chamber (2) is connected through pre-amplifiers (16), band pass filters (17), rectifier (18), low pass filter (19) and signal conditioning amplifier (20) to a signal read-out device (21). The operation of the apparatus is based on the measurement of the capacitance between the nozzle (5) and the inner chamber (2). As a droplet (15) grows on the dispensing tip (7), the capacitance between the nozzle (5) and the inner chamber (2) increases. Therefore, the signal detected and received by the signal read-out device (21) changes. This change is directly related to the volume of the droplet which can therefore be measured.

Abstract: A dispenser (1) for liquid droplets of the order of 30 &mgr;l or less in volume. The dispenser (1) comprises a metering valve body (2) having a main bore (3) connected by a pipe (4) to a pressurised liquid delivery source (not shown). The body (2) comprises a base (5) from which is mounted a nozzle (6) projecting above the base (5) to form a valve seat (7). An actuating coil assembly (11) is mounted on the exterior of the body (2) for moving a floating valve boss (15) of a ferromagnetic material. Sensing coils (20, 21) are mounted around and spaced-apart along the body (2) forming part of a valve boss detector. The valve boss detector acts as a positional movement detector so that the opening and closing of the valve can be accurately controlled and bouncing of the valve boss (15) either against an end stop (9) or on the valve seat (7) can be greatly minimized, if not prevented fully, by careful operation of the actuating coil assembly (11).

Abstract: A dispenser (1) for liquid droplets of the order of 30 &mgr;l or less in volume. The dispenser (1) comprises a metering valve body (2) having a main bore (3) connected by a pipe (4) to a pressurised liquid delivery source (not shown). The body (2) comprises a base (5) from which is mounted a nozzle (6) projecting above the base (5) to form a valve seat (7). An actuating coil assembly (11) is mounted on the exterior of the body (2) for moving a floating valve boss (15) of a ferromagnetic material. Sensing coils (20, 21) are mounted around and spaced-apart along the body (2) forming part of a valve boss detector. The valve boss detector acts as a positional movement detector so that the opening and closing of the valve can be accurately controlled and bouncing of the valve boss (15) either against an end stop (9) or on the valve seat (7) can be greatly minimized, if not prevented fully, by careful operation of the actuating coil assembly (11).

Abstract: A conventional syringe pump (10) is used to dispense liquids of less than 5 &mgr;l in volume in a dispensing assembly (1). There is a divider barrier formed by a flexible elastomer membrane (5) clamped between an inner part (3) and an outer part (4) of a dispenser (2). The dispenser (2) has a bore divided into a system liquid reservoir (6) and a sample liquid reservoir (7). The system liquid reservoir (6) connects to the pump (10) and the sample liquid reservoir (7) communicates with a nozzle (15) having a dispensing tip (16). The membrane (5) is virtually incompressible and therefore the pump (10) can dispense accurately. Electrostatic drop detachment using an electrode (25) electrically coupled to the dispensing tip (16) and a conducting plate (19) forming a receiving electrode below a substrate (20).