Chemical etching the next generation of resonating biosensors

Highland Biosciences Limited, creator of leading edge diagnostics technologies, has partnered with Precision Micro in the development and manufacture of a miniaturised ‘tuning fork’ biosensor. The component forms an essential part of HBL’s proprietary micro-viscometer, that is claimed will improve the safety of a number of medical procedures by providing results conveniently at the point of need.

The biosensor design comprises of 3 micro-engineered stainless steel tines, which resonate many thousands of times a second, detecting microscopic changes in film thickness, density and viscosity of a liquid sample and converting the presence of bacterial toxins into an electronic signal.

With a tight innovation cycle needed, and a reliance on the material properties being unaffected during manufacture, both stamping and laser cutting were ruled out as viable methods of both prototype and serial production. HBL opted instead to use the chemical etching process.

Using tightly controlled chemistry to selectively remove metal atom by atom with micron accuracy, chemical etching imparts no stress or burr on the base material. The process is also highly versatile, with digital tooling allowing for design iterations to be carried in hours, rather than days and weeks.

As every biosensor produced requires a perfectly clean surface to ensure consistent adhesion of the surface coating, Precision Micro developed a dedicated post-process cleaning operation supported by 100% automated optical inspection.

“We have been constantly impressed by the level of expertise at Precision Micro; with their support, we have been able to quickly get to a mass-producible design and to receive our parts with minimal downstream processing, ” said Dr Richard Day, managing director at HBL

Both innovation and the advanced etching techniques employed in the production of the biosensor were recognised by the Technology Strategy Board (TSB), the UK’s leading innovation agency.

“By overcoming major competition from other companies from all over the UK, our team managed to attract TSB funding for a 1 million pound manufacturing development project,” said Dr Day.

He concludes, “The TSB project focuses on the mass-manufacturing and scale up technology needed to launch the first product.”

With development now near to completion, the biosensor is being readied to make the transition to volume manufacture, expected to reach 50 million components over the next 5 years, utilising the same digital tooling and to a quality comparable to parts produced in silicon.