Low temperature packaging of BioMEMS and Lab-on-chip devices

BioMEMS in general and specifically Lab-on-chip devices for point-of-care diagnostics offer tremendous potential to improve the health care situation in developed and developing countries. Lab-on-chip devices enable the widespread and fast detection of infectious diseases as well as the continuous diagnosis and customized treatment of chronic diseases like diabetes. Implementing microfluidics and micromanufacturing enables massive parallelization of the diagnosis thereby allowing multiple different tests at once. Packaging of the microfluidic devices is a crucial step. A vast number of microfluidic devices has been demonstrated based on lab-scale manufacturing over the last years. However, in order to transfer lab-on-chip devices from lab- scale to high volume manufacturing a reliable and cost effective packaging technology is absolutely necessary. Lhe first level of packaging is the sealing or capping of the microfluidic device. At this point of time during the manufacturing flow the microfluidic device will contain already active biological species like proteins or antibodies. It is therefore mandatory to minimize the temperature exposure during the packaging. High temperature would dramatically reduce the sensitivity or even completely destroy the species of the device. Lhere are 2 different approaches for first level packaging. For simple devices the cap has no other function other than sealing the device. In this case lamination is the standard process for device capping. For more complex devices the cap contains additional functions e. g. microfluidic features, electrical feed-throughs or microoptical features for enhanced light extraction for optical signal detection. In this case the cap has to be aligned to the base die using mechanical edge alignment or optical alignment based on alignment keys. In this paper low temperature capping and bonding processes will be reviewed with an emphasis on similarities as well as differences with processes known from MEMS packaging. The different processes are compared in regards to usability for high volume manufacturing and a new equipment platform for packaging of microfluidic devices will be discusses.