The need
AgPlus has developed a portable diagnostic platform which can quickly identify a wide range of illnesses from a blood or saliva sample, allowing rapid point-of-care diagnosis. Faster point-of-care diagnostics will allow earlier interventions to treat illness, and reduce patient anxiety associated with waiting for test results.
They have been licensing their technology for R&D applications within human clinical diagnostics, and now expect to launch the first mass-produced diagnostic tool for clinics and hospitals in 2019.
Their technology uses an innovative diagnostic technique. Silver nanoparticles are coated with an antibody which makes them bind to compounds in the sample which are indicative of particular diseases. The number of silver nanoparticles, after being separated from those that didn’t bind, is proportional to the amount of compound in the sample – which can then be linked to a condition. Measuring the nanoparticles involves changing the voltage across two electrodes, which changes the silver nanoparticles into silver ions. Measuring the charge of these ions shows their quantity.
AgPlus had an issue with the mass production of their electrodes. They were produced with a printing process, but there were issues with consistency, leading to unacceptably high rates of failure. AgPlus, as a small business, did not have the advanced analytical technology needed to identify the source of the problem, or the quality control technology to identify poorly performing electrodes before the device was assembled.
The solution
NPL examined batches of electrodes using advanced analysis methods, including 3D microscopy, elemental analysis, electrochemical impedance spectroscopy and electrochemical imaging – techniques beyond the capabilities of AgPlus’ inspection facilities. The electrodes were rough, so it was necessary to measure the thickness in several ways to get conclusive values. The two organisations characterised the electrodes, identifying the correlation between structure, electrochemical performance and chemistry of various electrodes.
The research found the printing thickness to be unsuitable – the roughness of the electrodes was too great for the existing nominal thickness to consistently fully coat the sensor. Batches were then created with different thicknesses – NPL and AgPlus carried out further measurements to identify the optimal thickness to give confidence in the end product.
The impact
The project improved electrode design, reducing failure rates to the levels needed as they scale up to mass production. The project also identified changes to their quality control methods which have saved time and improved productivity.
This gives AgPlus greater confidence in the performance of its product and in its manufacturing processes as it brings the product to market.
This work was done as part of the Analysis for Innovators programme.
