Micro-valves are basic components of microfluidic systems as they allow fluids to be conveyed, exchanged and controlled. These devices may be either connected on a platform with microfluidic channels or integrated within more complex microfluidic systems. Micro-valves may be employed for applications such as fluids dispensing, high-speed gas chromatography and drugs delivery, which require small fluid volumes and high control. We target biomedical sector companies for point-of-care and lab-on-a-chip type applications. The device is a pneumatically driven membrane-type microvalve with silicon body and biocompatible polymer membrane, developed and produced in cooperation with CNR - IMM of Bologna.
(a) SEM image of the device section (b) device diagram
The small volume makes the device highly integrable into microfluidic systems. These valves, reliable and tight, may be used in a variety of environments, in a wide range of temperatures and are chemically inert. Furthermore, they have the advantage - with respect to traditional diaphragm valves - of being integrated on microfluidic circuits by using the standard MEMS technology on wafer.
The device may be employed in high speed gas chromatography type applications. In utilisation for liquid control we target biomedical sector companies for point of care and lab-on-chip type applications. Thanks to the diaphragm chemical resistance, these valves may be also used in the aerospace sector for micro fuel control in micro satellites.
Chip with three valves
Miniaturised injector for high speed gas chromatography systems (HSGC)
The 2-way, normally open pneumatic micro-valve with polymer membrane has been used to produce injection systems for “FAST-GC” type gas chromatography (GC) equipment (HSGC) The chip sized 12x12 mm2 has been produced in two versions: the first consists in 5 micro-valves and integrates a sample-loop volume of a few micro-litres. The second version consists in 3 micro-valves and uses two chips to make external loop injection possible. In both cases, the micro-valves are externally pneumatically driven by trade solenoid valves driven by a suitable control board. These injectors have been used within the European Project FP7-SEC-DIRAC (grant agreement 242309) for FAST-GC pre-concentration and separation of drugs and doping substances in security applications (inspection of containers at customs). The system has shown excellent performance in a wide temperature range (tested up to 130 °C), also proving to have chemical inertia, a required property for applications in chemical analytical systems. Reproducibility, linearity and speed of the injection time are other important properties of the system, as well as assuring low dead volumes.
CREO Consortium, L’Aquila Fraunhofer IPM, Freiburg, Germany EADS Innovation Works, München, Germany Company in the environmental chemical analysis sector
Two-way pneumatic micro-valves feature extremely low dead volumes, which make them suitable to implementing injection systems for innovative FAST-GC analytical systems. Thanks to their small size, they are mainly used in miniaturised and portable gas-chromatographic systems (suitable for use in the field), in emerging applications such as safety&security, industrial monitoring, health (including breath-analysis) and food safety.
“FAST” module for steam pre-concentration and gas-chromatographic separation.