Evaluation of synthetic setae pads for dry attachment of an ultrasound transducer

Medical ultrasound requires the coupling of skin with the transducer. Removing this requirement could make ultrasound stimulation and imaging more accessible and convenient. Synthetic setae pads are a biomimetic material that mimics the structure of a gecko's foot, allowing it to hold substantial weight. By combining synthetic setae with an ultrasound transducer, the attenuation of existing commercial versions was measured using a 10 MHz ultrasound transducer. It was found that ShearGrip® attached to a smooth plastic surface (70.0% power loss) had notably less attenuation than to skin (86.5% power loss). The material was also examined by mounting it on the side of plastic tank, using a 5 MHz ultrasound transducer and hydrophone. In the case of the tank tests, the presence of moisture on the synthetic setae specimen was found to reduce attenuation by 0.29 dB. Otherwise, the attenuation could be 0.35 dB. However, this large attenuation was due to sample porosity and thickness, causing scattering and energy loss. Currently, work is underway to fully characterize the material. Potential improvements to the material's acoustic conductance include uniform fiber alignment, reduced porosity, optimized thickness, and the use of lower frequency ultrasound stimulation.