Fig. 1: A-mode 32 channel dry-coupling ultrasound bracelet.

a Single-element transducer holder design and assemble in wearable bracelet format. b A-mode ultrasound echoes, with and without silicone, in a water bath with a large plastic reflector. With silicone the echo is longer with a small artifact at the end due to internal reflections inside the silicone, but the amplitude is comparable in both cases. c A-mode ultrasound echos on a participant forearm aiming at the ulna with and without silicone. Both were recorded at approximately the same position and angle. Similarly to the water bath, the A-mode ultrasound echo with silicone shows a longer reflection from the bone with a small artifact at the end but only a small difference in amplitude. d Illustration of the recording scheme. All transducers transmit one at a time, while every other transducer receives. This is performed for every transducer sequentially, generating a single frame of US scanning. Echoes received by each transducer are therefore dependent on which one is transmitting. In this example raw data from 16 transducers (one row) are seen when, from left to right, transducers 0, 16, and 30 are transmitting.