By Mark Tondra
Combining microfluidic devices with MEMS and silicon based sensors to make “Lab on a Chip” or BioMEMS products is a rapidly growing commercial enterprise. Typical applications include biosensors, flow sensors, microincubators, bioreactors, and micro-environments. As these hybrid systems become smaller and more integrated, they also become cheaper and more generally useful. This positive development trajectory may create new opportunities and disruptive technology. However, there are challenges to this area of development including technical, regulatory, and manufacturing. This presentation will focus on the manufacturing challenges and how some specific interface standards are developed to enable more rapid manufacturing development and product design cycles.
A new set of standards from SEMI and other international industry organizations are being developed to address these commercialization needs. SEMI Ballot 4691 titled
“SPECIFICATION FOR HIGH DENSITY PERMANENT CONNECTIONS BETWEEN MICROFLUIDIC DEVICES” has been passed in early 2011 and should be published by the end of 2011. The standard assumes that hybrid device may include a laminated microfluidic card made of glass and or plastic from one manufacturer, and a silicon or semiconductor chip from another. The product designer is from a third company, and does not control all aspects of the component design.
This new SEMI Standard provides a set of detailed requirements for specifications that a manufacturer must include on their product data sheet to describe their product’s fluidic and electrical interface with other components, such as: intended sealing method, port size (inside diameter), port spacing, port location, number of ports in a row or array, any physical alignment features, and the material composition of the flow path. It also provides some sets of specific port spacing and dimensions that can become an industry standard. One emphasis is on ensuring that the entire architecture is scalable upward and downward in dimensions. The constituency of the standard development process, primarily manufacturers, will be described.
For an example of a specific implementation of the standard; Diagnostic Biosensors, LLC, has announced prototype sensors that have fluidic-to-silicon interfaces that meet many of the Standard’s requirements. The silicon sensors have molded plastic microchannels whose flow-out-of-plane connection ports are formed by molding over long pins and thinning back until the ports are exposed. Center to center port spacing is 0.500 mm, port diameter is 0.250 mm. These ports can be mated directly to matching ports on a designed multilaminated “lab card”, or fluidic connections can be made to tubing and Luer lock connectors. For this second option, bundles of 2 or 4 Tygon inlet tubes with an ID and OD of 0.254 mm and 0.762 mm, are brought to a “fluidic interface housing” on the sensor through a molded plastic “tube adapter” with a center – to – center pitch of 0.800 mm. The fluidic housing carries fluids between the inlet tube adapter and the ports on the top face of the microfluidic cover. All of the molded plastic is acrylic or polycarbonate, formed using a hot embossing process (CAMD – LSU); the mold is CNC milled brass. The pieces are bonded together by sealing with UV curable glue.
Some technological innovations that are known to exist but have not been demonstrated on microfluidic products: pick and place machines for fluidic components, automated glue dispensing and curing.
Copyright AZoNano.com, MANCEF.org