Droplet dispensing systems

This invention generally relates to methods and systems for dispensing a droplet, in particular a picolitre volume droplet containing one or more entities. We disclose herein a microfluidic droplet dispensing system comprising: a droplet feed line to carry droplets for dispensing; a dispensing line to carry dispensing fluid for dispensing the droplets; a droplet outlet line coupled to a droplet outlet; a first junction having a first input to receive a flow from said droplet feed line, having a second input to receive a flow from said dispensing line and having an output to said droplet outlet line; a waste line coupled to said droplet output line between said first junction and said droplet output; a first pressure source to provide pressurised dispensing fluid to said dispensing line to eject droplets from said droplet output; a droplet dispensing valve between said first pressure source and said dispensing line to control the ejection of droplets from said droplet output; wherein the system further comprises: a second pressure source to provide pressurised dispensing fluid to a droplet protect line; a second junction having a first input from said droplet feed line, having a second input from said droplet protect line, and having an output; and a volume flow throttle coupled between the output of said second junction and the first input of said first junction to restrict a volume flow from said second junction into said first junction.