Droplet dispensing systems

A microfluidic droplet dispensing system 100 comprises a droplet feed line 105 to carry droplets for dispensing and a dispensing line 110 to carry dispensing fluid for dispensing the droplets, the lines meeting at a junction to output to a droplet outlet line 120 coupled to a droplet outlet 125, the system further comprising a waste line 130 coupled to the droplet output, a pressure source to provide pressurised dispensing fluid to eject droplets from the droplet outlet, a droplet dispensing valve 115 to control the ejection of the droplets and an injection line 245 coupled to the waste line. A method of using the system comprises injecting fluid through the injection line into the waste line when pressurised dispensing fluid is provided into the droplet outlet line. A further method of dispensing a droplet of fluid includes protecting droplets upstream of a droplet outlet line by providing pressurised dispensing fluid upstream of a droplet outlet line. Pressure fluctuations within the microfluidic system can be minimised. The methods may relate to emulsions, typically microdroplets of water in oil. Biological entities may be incorporated into each droplet.