Tablet manufacturing

Novel imaging technologies for monitoring thin films

Distinct features of terahertz (THz) and optical coherence tomography (OCT) technology are their 3D-imaging capabilities that reveal not only the surface features but the internal structures of an object. Researchers at the University of Liverpool are studying the development of novel 3D-imaging technologies to provide solutions to key industrial challenges. Current real-world applications involve the intelligent inspection of pharmaceutical tablet coatings and quality assurance in the automotive industry.

The challenge

In both the pharmaceutical and automotive industries, it is extremely important to manufacture functional coatings to high quality. But there is no suitable technology to non-destructively monitor the uniformity of the coating process in real-time.

In the pharmaceutical industry, functional coatings that control the sustained release of the active ingredient are increasingly common: if the coating is defective or non-uniform it can compromise effective drug delivery. In the automotive industry, the smooth application of multiple layers of paint plays an important function in corrosion prevention, as well as guaranteeing an attractive metallic finish.

Research action

Professor Yaochun Shen has been working on THz-related technology since 2001, applying technology in collaboration with industry to develop novel methods for better monitoring and quality control of pharmaceutical and car painting processes.

The underlying research involves the development of novel electromagnetic (EM) sensing and monitoring devices, as well as associated algorithms that extract critical measurements from imaging data. The hybrid sensor uses THz imaging for measuring thick coatings, whilst the OCT method is used for thin coatings, allowing monitoring of the whole coating process.

The group has also developed a high-speed OCT online sensor for capturing cross-section images of moving tablets, allowing real-time, non-destructive characterization of the tablet’s internal structures.

Working in partnership

Close collaboration with a UK-based high-tech company has ensured that the novel devices and algorithms developed at Liverpool are optimised for industry needs, rapidly implementable in the manufacturing processes of large multinational companies and research institutions.

The UK based company, together with its wide customer base, has enabled new business opportunities with international healthcare companies, as well as tailoring the technology for the automotive industry.

The underpinning research carried out by Professor Shen’s team has been funded by grants from Innovate UK, EPSRC and through industrial collaborators, including funding from one of the world's largest pharmaceutical companies. An additional impact acceleration award from business gateway has assisted trial measurements with a major pharmacy.

Outputs and outcomes

The technology is being optimised for the specific measurement environment and is being trialled by one of the world's largest pharmaceutical companies. The technique provides unparalleled quality monitoring, enabling non-destructive real-time monitoring and quantification of coating layer thickness in fast-moving rotating tablets as they are made. This allows the pharmaceutical industry to improve their manufacturing efficiency, product yields and quality, therefore minimising human and material costs.

Recently the group has demonstrated that the developed THz imaging technology can also be used to measure and monitor complex car paint processes. The numerical algorithm developed at Liverpool allows quality control of the paint layers and it has now become an essential part of the world’s first THz instrument for automotive market.

High-tech sensor technology allows real-time, non-destructive characterisation of coating processes, ideally suited to modern pharmaceutical and automotive industries.

Professor Yaochun Shen

Back to: Department of Electrical Engineering and Electronics