'Just-in-time' electromechanical know-how helps Bayer Healthcare Diagnostics deliver robust and simpler point-of-care urine analysis
A durable and intuitive motion control system designed by Cambridge Consultants to withstand harsh use - and even accidental abuse - is helping the diagnostics division of Bayer HealthCare to introduce greater simplicity of operation in point-of-care urine analysis.
The development of a new point-of-care analyser - Clinitek Status - with unique capability to read urine strips and immunoassay cassettes, required a more robust motorised drawer system than had been employed in previous instruments.
Cambridge Consultants provided design proposals that it says were successfully tested, within a fast turnaround time, and kept the instrument development on schedule.
"We required a motorised table that could withstand the rigours of daily use by multiple different operators, using different kinds of reagent.
"Previous systems used a simpler mechanism that only transported one type of reagent.
"We were concerned that they would not meet our desired reliability specification," said Trevor Allison, R and D director at Bayer Diagnostics's product development and manufacturing facility in the UK.
"To address the requirement we needed both a fast answer, and preferably one that could fit easily with our existing investments in production tooling and processes.
"Cambridge Consultants worked in parallel with us and provided the answer within a matter of weeks, keeping an important product launch on schedule".
The Clinitek Status analyser automatically analyses urine strips, eliminating the errors that can arise from human visual judgements.
It is particularly simple to use because of a touch-screen user interface, and a motorised drawer that accepts the reagent strip or cassette and automatically positions it under the instrument's optical analysis sensors.
This drawer was the focus of Cambridge Consultants's engineering effort.
Previous sample drawer systems worked perfectly under normal conditions with operators who knew the instrument, but prototype testing highlighted a possible problem with new users - staff with no training.
Unsure about manually pushing the drawer in, they could use too much force and damage the motor's gear teeth.
Bayer decided to seek external help from Cambridge Consultants, which had been employed on numerous engineering projects before, and which offered extensive expertise in motion control and electro-mechanical areas.
"The problem was relatively simple to define as a design task.
"The major issues were how fast it could be produced, and the desire for the design to fit with current production tools and processes," added Trevor Allison.
"We started with a detailed analysis of the specific motion control problem, both in isolation and in the context of the overall product", says Richard Snell of Cambridge Consultants.
The motion control system that Cambridge Consultants devised involved a heavier-duty motor and gearbox than had been used in previous systems.
It was also specifically located to ensure that force on the drawer could never damage it.
This was combined with electronic circuit advice to assist the Bayer team in the design of an improved control and drive strategy.
This involved sensing the insertion of the drawer by feedback from the motor windings, and driving the motor in a more sophisticated way, with a special motion profile that improves both the engagement process and the final positioning of the reagent under the optics.
The sample drawer itself and the mouth of the enclosure were also designed to make table insertion intuitive - with mechanical shaping and visual indication of the right orientation.
These mechanical changes were achieved using modifications to existing moulding tools.
This avoided the time and cost involved with producing completely new tools.
"On tasks like this, with demand to complete in a short time period, our project control scheme called for all the mechanical specifications and tolerances to be meticulously verified, to ensure that everything would fit perfectly, and for rigorous tests to prove the design's robustness and reliability - giving the client the confidence to put our design modification straight into manufacturing," added Richard Snell.
After 18 months of commercialisation, the Clinitek Status analyser has already become successful in its segment of the urinalysis market.
With thousands of installations worldwide, undergoing high-frequency daily use in hospital wards and healthcare practices, there have been no failures attributable to design problems with the new moving-part mechanism.
