change material can be dispensed at a temperature other than ambient temperature and transition from the liquid phase to the non fluid phase as its temperature approaches ambient temperature further the phase change material can be reversible to reverse the process and convert the non fluid phase back to a liquid phase transition to a liquid phase enables subsequent pressure driven flow control at the input output node and or removal or addition of the phase change material a phase change material as considered above can be configured to conformally seal around a conduit inserted into the input output node while also controlling pressure driven flow in the microfluidic flow network fig3 shows an example where non fluid phase 114 conformally seals around conduit 302 in input output node 304 conduit 302 can be an electrode which enables electrical transport into and out of the microfluidic system in this case the phase change material can act as an ion reservoir alternatively conduit 302 can be a tube which enables species transport into and out of the microfluidic system these approaches provide the capability of connecting a conduit to a microfluidic system through an input output node while simultaneously preventing undesirable pressure driven flow effects by locally sealing off the input output node from the ambient in some cases multiple channels of a microfluidic network are in contact with the same input output node fig4 a shows an example where channels.