Challenges are what make life interesting – Yongqiang Qiu
Published: 4 January 2018
The ultrasound transducer is one of the core parts in capsule ultrasound devices. The addition of ultrasound imaging in capsule endoscopy carries great potential in early detection of GI diseases through analysis of the GI subsurface features. My main role in Sonopill is to develop ultrasound transducers to suit this purpose. The challenges in prototyping these transducers are making my life interesting.
The ultrasound transducer is one of the core parts in capsule ultrasound devices. The addition of ultrasound imaging in capsule endoscopy carries great potential in early detection of GI diseases through analysis of the GI subsurface features. My main role in Sonopill is to develop ultrasound transducers to suit this purpose. The challenges in prototyping these transducers are making my life interesting.
Frequency – Most medical ultrasound systems utilise frequencies < 20 MHz to balance the penetration depth and the resolution requirements. Higher frequency ultrasound (e.g. >25 MHz) is necessary for accurate assessment of the GI wall features.
Size – Only limited space is available for the transducer in the capsule, the transducer needs to be miniaturised to fit in the constrained space.
Transducer types and arrangement – The type and arrangement of the transducer are determined by many different design factors. Similar to the rotational optical camera in some video capsules, single element transducers can be integrated with adequate rotation mechanics. Things get much more complicated with a transducer array, and the high frequency brings a few more challenges in terms of the small element width and complex interconnects.
Ultrasound coupling – In general, conventional medical ultrasound probes have an acoustic matching layer and an acoustic lens to improve the transmissivity of the ultrasound and use ultrasound gel to avoid air between the probe and tissue during the scan. Ideally, similar layer structures should be used in capsule ultrasound devices to reduce the reflection caused by the capsule shell. This could further increase the fabrication complexity and difficulty. To ensure good coupling during the device operation, adequate coupling media and a capsule motion control mechanism would be useful to clear undesired obstacles between the capsule and the GI wall.
Many challenges exist in the fabrication, along with other challenges that have been discussed in my colleagues’ blogs, e.g. power, ASICs, localisation, communication, packaging, biocompatibility, etc. However, these challenges are one of the reasons why I like this project.
Lastly, the future may not be so far away!
First published: 4 January 2018
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