Microfluidic device with positive displacement pump

A microfluidic device comprising:

• a microfluidic channel;
• a positive displacement pump comprising a chamber fluidically connected to the microfluidic channel, wherein the positive displacement pump is configured such that when the positive displacement pump is actuated, fluid within the chamber is displaced into the microfluidic channel;
• and
• a fluid reservoir fluidically connected to the chamber of the positive displacement pump to provide a source of fluid to re-fill the chamber after the positive displacement pump has been actuated, wherein the fluid reservoir is configured such that fluid within the reservoir is sealed within the microfluidic device, wherein the fluid reservoir comprises a fluid storage chamber of the microfluidic device and the fluid storage chamber is a waste chamber configured to store waste liquid on the microfluidic device, wherein the microfluidic device comprises a fluid loop configured for providing a continuous fluid flow channel between the microfluidic channel and the positive displacement pump, wherein the fluid storage chamber is connected such that it forms part of the continuous fluid flow channel, wherein the fluid storage chamber comprises:
• a first and a further fluid storage chamber port via which the fluid storage chamber is connected to the continuous fluid flow channel, wherein the first and further fluid storage chamber ports are hollow spikes that extend into the fluid storage chamber above a base surface of the fluid storage chamber such that liquid can be stored within the fluid storage chamber below the level of the first and further fluid storage chamber ports.