Wireless transmission of ultrasonic waveforms for monitoring drug tablet properties and defects

The geometric and mechanical properties of pharmaceutical materials are crucial to their structural, functional and therapeutic effectiveness. The implementation of automated and convenient quality monitoring procedures is an attempt to balance control of quality against the level of testing; within acceptable levels of probability and costs. The capability of rapid/extensive inspections with minimal time and manufacturing interruption make non-contact quality monitoring systems a desirable approach to optimize this balance. In the current study, a wireless transceiver proof of concept system developed for the real-time quality monitoring of tablets during compaction is presented and demonstrated. The effectiveness of ultrasonic wave transmission through the punch-tablet interface is the boundary condition that dictates the viability of the acoustic in-die compaction monitoring approach. These measurements in the current experimental set-up can be used in determining various mechanical and geometric properties of a compact, such as the tablet thickness, mass density, elasticity and/or integrity of the tablet core, and bonding quality between layers depending on the given parameters, as it is compacted. In the current study, it is demonstrated that the reflection of an ultrasonic pulse generated by a transducer embedded in an upper punch from the lower punch-tablet interface can be acquired by the same transducer in the upper punch and the analog waveform can be transmitted to a computer by means of wireless communications for further signal processing and property extraction. The evolution of apparent Young's moduli of a powder bed during a full-compaction cycle is derived from the ultrasonic time of flight of an acoustic waveform acquired during compaction in-die.