We are getting to the stage in the Sonopill programme where parts of the project are beginning to coalesce. This is in no small part due to the various constraints we have encountered over the last year I have been on this project, whether it is due to the volume of the capsule, power consumption required, clinical need or human physiology. These constraints have helped to focus problems, spurred creativity and have highlighted clear challenges to overcome. Another benefit of these constraints is that they have helped build strong bonds between team members due to the many discussions on how best to approach these challenges, each member bringing a new perspective to many of these problems due to the multi-disciplinary nature of the project.

In my own work on micro-engineering and packaging these constraints have directed my research. One of my tasks is to create a capsule no bigger than 10mm x 30mm, with a wall as thin as possible to increase internal volume for the various components while ensuring mechanical rigidity and biocompatibility. These constraints were identified after a lot of discussion between myself, Holly Lay and Benjamin Cox, a clinician on the project. Everything from the design, how they are manufactured, assembled and made from is impacted by these challenges.

They have also helped us to work out what is possible, what is needed and what is probable. This has helped shape our specification document, which has in turn helped see how individual systems connect together and impact others. Early on, one of the main challenges identified was power consumption. Many current pill cams use coin batteries to power the camera and internal electronics. These will likely not be an option for Sonopill due to the size (many have a diameter of 11 mm) and the fact that their energy density will not be sufficient to power all the systems embedded within the pill. We need another long term solution if we wish to have a tetherless pill so the merits of solutions such as low power design, wireless power transfer and supercapacitors are regularly discussed and assessed.

Another constraint is the bandwidth of the communications antenna being developed by Julia Faerber. Clinicians require a high resolution map of the gastrointestinal system for diagnosis, which means that the ultrasound data rate, camera data rate and their respective image frame rates will have to be as high as possible while again ensuring it can fit within the capsule, can be realistically manufactured and does not consume much power. These constraints have spurred a lot of discussion between Julia, Holly, Benjamin and I.

The Sonopill programme presents a lot of technical challenges across all fronts. These can be daunting at times but they should spur us to develop innovative, interdisciplinary solutions. Over the next few months, myself and other the team members will bring many of these solutions from the drawing boards to prototypes and most likely encounter more constraints and challenges.

First published: 8 December 2016

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