Disposable cartridge for microfluidics systems

A method for manipulating samples in liquid droplets (23) that adhere to a hydrophobic surface (17) of a working film in a digital microfluidics system (2) or device, the method comprising the steps of:

• (a) providing a working film in the form of a bottom layer (3) with a first hydrophobic surface (17′);
• (b) providing a digital microfluidics system (1) with an electrode array (9) that substantially extends in a first plane and that comprises a number of individual electrodes (10) supported by a bottom substrate (11) and connected to a central control unit (14) of the digital microfluidics system (1) for controlling the selection of individual electrodes (10) of said electrode array (9) and for providing these electrodes (10) with individual voltage pulses for manipulating said liquid droplets (23) on said first hydrophobic surface (17′) by electrowetting;
• and
• (c) providing a gasket (36) for defining a gap (6) between a second hydrophobic surface (17″) of a cartridge (2) and said first hydrophobic surface (17′) of the bottom layer (3),
• wherein the method comprises the steps of:
• (d) placing the bottom layer (3) that is configured as a flexible film on an uppermost surface (52) of a cartridge accommodation site (8) of the digital microfluidics system (1) and thereby creating an evacuation space (46) which is defined by said uppermost surface (52), the gasket (36) that also is provided at the cartridge accommodation site (8), and the flexible bottom layer (3);
• (e) establishing an underpressure in said evacuation space (46) using a vacuum source (33) that is linked to a number of suction holes (35) which penetrate the electrode array (9) and/or the bottom substrate (11) and which are located at the cartridge accommodation site (8) of a base unit (7) of the digital microfluidics system (1), the gasket (36) sealing the evacuation space (46) and the underpressure in the evacuation space (46) causing the flexible bottom layer (3) to be attracted to and spread over the uppermost surface (52) of the cartridge accommodation site (8) of the digital microfluidics system (1);
• (f) adding processing liquids to said first hydrophobic surface (17′) of the flexible bottom layer (3);
• (g) placing a rigid cover plate (12) with a lower surface (48′) on the flexible bottom layer (3), contacting said lower surface (48′) to and sealingly attaching said lower surface (48′) with a circumference (40) of the flexible bottom layer (3), thereby assembling a disposable cartridge (2) at the cartridge accommodation site (8) of the digital microfluidics system (1), the gasket (36) defining a particular distance between said first hydrophobic surface (17′) and said second hydrophobic surface (17″);
• and
• (h) adding at least one sample droplet (23) to the gap (6) and manipulating said sample droplet (23) by electrowetting.