Capsule endoscopy for diagnosis in the gastrointestinal (GI) tract has emerged only in the past ten years. Now established in several commercial products in companies such as Olympus and Medtronic and benefitting more than one million patients, it is a clear candidate for further innovation. The core of the SONOPILL programme is the exploration of ultrasound imaging and therapeutic capabilities deployed in capsule format. This is supported by extensive pre-clinical work to demonstrate the complementary nature of ultrasound and visual imaging, along with studies of multimodal diagnosis and therapy as the SONOPILL travels through the GI tract. This is opening up both challenges and opportunities in areas including ultrasound device and systems design, microengineering and microelectronic packaging, sensor suites for diagnosis and intervention, and routes to translation into clinical practice. Our programme's carefully structured but open-ended approach maximises the possibility to meet these challenges while delivering international leading science and engineering in multimodality capsule endoscopy. The ultimate aim is to provide greater capabilities for the clinician, more acceptable practice for the patient population, and lower costs for economic wellbeing.