PCB-based microfluidics promise low-cost medical sensing

A new look at PCB fabrication could lead to on-the-spot medical tests for disease, reports Steve Bush.

Themis Prodromakis and Philip King

Themis Prodromakis and Philip King

Key to the development is the identification, by University of Southampton researchers, that a PCB manufacturing plant has everything needed to make micro-fluidic bio-chemical sensors. Disposable cartridges made like PCBs would clip into a hand-held analyser – also being development at Southampton.

The idea is to automate the ‘enzyme-linked immunosorbent assay’ (ELISA) process – the gold standard for detecting certain viruses and protein expressions, according to Southampton scientist Dr Themis Prodromakis.

Currently, said Prodromakis, ELISA is either fully manual – involving someone dripping liquids into small containers with a pipette – sometimes periodically for up to 12 hours – or it is done automatically by something akin to inkjet printing – which is expensive enough to require one machine in a central office to serve multiple medical facilities.

Microfluidics machined into silicon on a CMOS-like process is another alternative, which offers extreme parallelism – good for DNA analysis – and very cheap chips – in the order of 1p he said. Unfortunately this 1p can increase up to $200 when the associated fluid interfaces have been added to the chip. If only a few simple tests are needed, say under 100 virus checks, this is expensive over-kill.

Prodromakis believes that all the appropriate fluidic channels, coated electrodes, and other features necessary for ELISA can be made on a normal PCB production line using standard routing and plating. If the sub-mm channels achieved with normal routing are insufficient, micro-scale channels can be formed with the laser routing now becoming available in PCB plants.

“It doesn’t need to be super-engineer. The cleverness is in the design of the disposable cartridge. It just needs simple PCB electrodes and microfluidics,” said Prodromakis. “We already have preliminary data. We have demonstrated the concepts in research over the last few years.”

“It will be portable, and valuable because of the lower cost. You could use it in Africa. It will be extremely versatile – HIV or TB tests will need a couple of disposables and a few minutes,” said Prodromakis.

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