Manufacturing microfluidic biosensors

Fraunhofer IZM, Germany reports that high throughput manufacturing of biosensors has remained a challenge. This is due to the different environments necessary for the survival of biological components on the one hand and current MEMS technologies on the other. This has been one of the major obstacles en route to successful commercialisation of biosensors for a wide range of applications. The challenge will be met by Fraunhofer IZM and their partners within the European Framework 6 project, DVT-IMP.

 

A biosensor consists of the combination of a physical device, often fabricated using Microsystems technologies, and a biological component that provides recognition capabilities for the desired analyte. This combination provides distinct advantages: highly specific recognition of the analyte as only provided by interactions of biomolecules (e.g. enzyme-substrate or antibody-antigen reactions), and efficient translation of this biomolecular recognition into a physical signal for the sensor output. Microsystem technologies allow reducing the size of the biosensor systems to credit card size or even smaller, making them attractive for point-of-care and home-care diagnostics.

 

The manufacturing challenge of such devices lies in the lack of compatibility of MEMS processes and biomolecule survival. Difficulties can be prevented for simple systems, open to user intervention. The glucose monitoring strips for diabetics are a good example of this. However, as soon as the biosensor reaction becomes a bit more complex and requires more than a single reagent for the assay, only closed microfluidic systems provide the required functionality. Here the biomolecules get hit full force by the microsystem process environment: from a manufacturing point of view there is no viable alternative to introducing the biomolecular components before system closure - it allows both faster manufacturing and precise and selective placement of the biomolecules.

 

These issues are being addressed in the European project DVT-IMP for the specific application of a biosensor for D-dimer. It requires converging towards a solution from different sides: biomolecules have to be stabilised by immobilisation and protective measures while novel assembly technologies are developed that increase survival of the biomolecular components. One key component in this strategy is the use of polymer as the base material for the microsystem. Another is the development of bonding technologies that are harmless to the biomolecules.

 

Here the biomolecules get hit full force by the microsystem process environment: from a manufacturing point of view there is no viable alternative to introducing the biomolecular components before system closure - it allows both faster manufacturing and precise and selective placement of the biomolecules.

 

Development in these areas will pave the way for high-throughput fabrication of complex polymer-based microfluidic biosensors. As part of DVT-IMP, a roll-to-roll process for the functional layer of the microfluidic biosensor is under development to demonstrate the capabilities and assess the remaining challenges before mass production of biosensors will truly become a standard technology.

 

Categories of work relevant to printed electronics include:

 

System/component integrator

Production machinery

Printing ink jet

Printing flexo

Printing litho

Printing gravure

Printing screen

Logic organic

Sensors

Work proceeds on in-line fabricated organic electronic devices and systems.

 

Fraunhofer- Institut for Zuverlassigkeit und Mikrointegration IZM is part of the Fraunhofer-Gesellschaft (Fraunhofer Society). The Fraunhofer-Gesellschaft undertakes applied research of direct utility to private and public enterprise and of wide benefit to society. Its services are solicited by customers and contractual partners in industry, the service sector and public administration. The Fraunhofer-Gesellschaft maintains roughly 80 research units, including 58 Fraunhofer Institutes, at over 40 different locations throughout Germany.

 

A staff of some 12,500, predominantly qualified scientists and engineers, works with an annual research budget of over one billion euros. Of this sum, more than 900 million is generated through contract research. Roughly two thirds of the Fraunhofer-Gesellschaft's contract research revenue is derived from contracts with industry and from publicly financed research projects. The remaining one third is contributed by the German federal and Lander governments, partly as a means of enabling the institutes to pursue more fundamental research in areas that are likely to become relevant to industry and society in five or ten years' time.

 

For more read Organic & Printed Electronics in Europe  and attend Printed Electronics Europe 2008 .