Sparse-deconvolution terahertz near-field microprobe tomography enabling non-destructive inspection of small solid...

Area of Science:

• Pharmaceutical Sciences
• Imaging Technology
• Spectroscopy

Background:

• Terahertz (THz) pulsed imaging is vital for solid dosage form analysis.
• Far-field THz systems have limited lateral resolution for small or curved samples.
• Pharmaceutical coatings vary in thickness, posing analytical challenges.

Purpose of the Study:

• To develop a novel THz imaging approach for enhanced lateral resolution.
• To improve the analysis of pharmaceutical dosage forms, especially those with thick coatings.
• To enable reconstruction of faint interfaces in scattering media using advanced signal processing.

Main Methods:

• Utilized photo-conductive near-field microprobes (PC-NFMs) integrated with THz time-domain spectroscopy.
• Implemented a modified sparse deconvolution algorithm for THz signal processing.
• Applied the method to analyze controlled-release dosage forms with thick coatings as a worst-case scenario.

Main Results:

• Achieved high spatial resolution of 87 µm (x-direction) and 175 µm (y-direction).
• Successfully analyzed pharmaceutical coatings up to nearly 400 µm thick.
• Demonstrated reconstruction of faint interfaces in scattering media.

Conclusions:

• The novel PC-NFM THz imaging approach overcomes far-field resolution limitations.
• This technique is valuable for specialized dosage forms, including those with thick coatings and mini tablets.
• The enhanced spatial resolution and deconvolution algorithm offer significant advancements in pharmaceutical analysis.