Data underlying the publication: Ultrasound Transparent Neural Interfaces for Multimodal Interaction - Immersion experiments

<strong>Recorded data of immersion experiments</strong><br>The experiments were conducted in a 580 x 450 x 300 mm^3 water tank. Water was used as the intermediate medium as its density, sound velocity and sound impedance are near those of soft tissue. An acoustic-damping material was attached to the sides of the tank to minimise acoustic reflections. An ultrasonic transducer (V309-SU, Olympus, Japan) with a diameter of 0.5 inch (12.7 mm) was driven by an arbitrary function generator (33622A, Keysight, USA) and a 50 W linear power amplifier (350L, Electronics &amp; Innovation, USA). An ultrasonic pulse train with a duration of 15 μs and 4 μs rise and fall times was employed, sweeping frequencies from 1.25 MHz to 25 MHz in 1.25 MHz increments. The radiated ultrasonic signal passed through the fabricated samples, aligned and positioned 10 mm away from the transducer surface. To perform measurements of through-transmitted energy we employed a needle hydrophone (NH1000, Precision Acoustics, UK) with a diameter of 1 mm at a distance of 35 mm away from the transducer. The hydrophone was coupled with a submersible preamplifier and DC coupler. The samples were tested one at a time. By measuring the pressure with and without the sample placed between the transducer and the hydrophone, transmittance can be calculated by comparing the pressure collected through the sample and without the sample in the path. Therefore each transmission coefficient for each sample is calculated by comparing the two measurements. Both recordings and the corresponding transmission coefficient are saved in a hdf5 file. A custom-made 3D print was used to align the transducer, sample and hydrophone. The data acquired from the hydrophone were recorded using a digital storage oscilloscope (RTA4004, Rohde &amp; Schwarz, Germany). All applied and monitored signals were time-synced between the function generator and oscilloscope with trigger inputs. The monitored signals were averaged over 100 cycles and recorded with 1.25 GSa/s. The logged signals were streamed from the data acquisition hardware to a workstation PC using custom Python code to control the triggers, channels, and function generator output. The compiled C code which called the oscilloscope and function generator commands was in turn called within a Python wrapper.

<strong>浸没式实验采集数据</strong><br>本实验在尺寸为580×450×300 mm³的水槽中开展。实验以水作为传声介质，因其密度、声速与声阻抗均与人体软组织相近。水槽内壁粘贴吸声材料以降低声学反射。本实验采用直径0.5英寸（12.7 mm）的超声换能器（ultrasonic transducer，V309-SU，奥林巴斯，日本），由任意波形发生器（arbitrary function generator，33622A，是德科技，美国）与50 W线性功率放大器（350L，Electronics & Innovation，美国）驱动。实验采用时长15 μs、上升沿与下降沿均为4 μs的超声脉冲串，扫频范围为1.25 MHz至25 MHz，步长1.25 MHz。发射的超声信号穿过制备完成的样品，样品与换能器表面对齐且间距为10 mm。为测量透射超声能量，本实验采用直径1 mm的针式水听器（needle hydrophone，NH1000，Precision Acoustics，英国），其安装位置距换能器35 mm。该水听器连接有浸没式前置放大器与直流耦合器。样品采用单组依次测试的方式。通过分别测量换能器与水听器之间有无样品时的声压，对比有样品路径与无样品路径采集到的声压，即可计算得到透射系数。因此，每个样品的透射系数均通过两组测量结果对比计算得到。原始采集信号与对应的透射系数均保存于HDF5格式文件中。实验采用定制3D打印夹具实现换能器、样品与水听器的精准对准。水听器采集的信号通过数字存储示波器（digital storage oscilloscope，RTA4004，罗德与施瓦茨，德国）进行记录。通过触发输入信号，实现任意波形发生器与示波器之间所有激励与监测信号的时间同步。监测信号经100次循环平均后，以1.25 GSa/s的采样率进行记录。采集到的信号通过定制Python代码实现从数据采集硬件到工作站PC的流式传输，该代码用于控制触发设置、通道参数与任意波形发生器的输出。调用示波器与任意波形发生器指令的编译型C代码，通过Python封装层进行调用。