Worcester Polytechnic Institute, Worcester, MA 01609, USA.
Liberating Technologies, Inc., Holliston, MA 01746, USA.
Sensors (Basel). 2023 Apr 13;23(8):3954. doi: 10.3390/s23083954.
Wearable wireless biomedical sensors have emerged as a rapidly growing research field. For many biomedical signals, multiple sensors distributed about the body without local wired connections are required. However, designing multisite systems at low cost with low latency and high precision time synchronization of acquired data is an unsolved problem. Current solutions use custom wireless protocols or extra hardware for synchronization, forming custom systems with high power consumption that prohibit migration between commercial microcontrollers. We aimed to develop a better solution. We successfully developed a low-latency, Bluetooth low energy (BLE)-based data alignment method, implemented in the BLE application layer, making it transferable between manufacturer devices. The time synchronization method was tested on two commercial BLE platforms by inputting common sinusoidal input signals (over a range of frequencies) to evaluate time alignment performance between two independent peripheral nodes. Our best time synchronization and data alignment method achieved absolute time differences of 69 ± 71 μs for a Texas Instruments (TI) platform and 477 ± 490 μs for a Nordic platform. Their 95th percentile absolute errors were more comparable-under 1.8 ms for each. Our method is transferable between commercial microcontrollers and is sufficient for many biomedical applications.
可穿戴无线生物医学传感器已经成为一个快速发展的研究领域。对于许多生物医学信号，需要在身体周围分布多个传感器，而无需本地有线连接。然而，以低成本设计具有低延迟和高精度采集数据时间同步的多站点系统是一个尚未解决的问题。目前的解决方案使用自定义无线协议或额外的硬件进行同步，形成具有高功耗的自定义系统，这使得它们无法在商业微控制器之间迁移。我们旨在开发更好的解决方案。我们成功开发了一种低延迟的基于蓝牙低能耗（BLE）的数据对准方法，该方法在 BLE 应用层实现，使其在制造商设备之间可移植。该时间同步方法通过向两个独立的外围节点输入常见的正弦输入信号（在一系列频率下）来测试两个商业 BLE 平台上的性能，以评估两个独立的外围节点之间的时间对准性能。我们的最佳时间同步和数据对准方法为德州仪器（TI）平台实现了 69 ± 71 μs 的绝对时间差，为 Nordic 平台实现了 477 ± 490 μs 的绝对时间差。它们的 95%百分位绝对误差更为接近——每个平台都小于 1.8 毫秒。我们的方法可在商业微控制器之间移植，并且足以满足许多生物医学应用的需求。
