Ad8232

The multi-lead ECG wear and measurement system is shown in Fig. 6. The signals measured by the CFE at each position were connected to the flexible printed circuit (FPC) via snap buttons on the wearable device. Therefore, the wearable device and the FPC can be attached and detached both mechanically and electrically. The FPC is connected to a signal processing board with amplifiers (AD8232, Analog Devices) and a microcontroller unit (MCU; MSP430F55281YFF, Texas Instruments, USA). Eighteen amplifiers are included to measure the V1–V6 signals at the upper six electrodes, the middle six electrodes, and the lower six electrodes. These signals are then transmitted to a smartphone or personal computer (PC) via wires and the signals can thus be measured. The smartphone or PC supplies the power to the signal processing board.Figure 6

Wearable multi-lead ECG measurement device and data acquisition system.

To evaluate the differences of neuronal activities of autonomic nerve fibers innervated on heart and the sudomotor nerve fibers in sweat glands in human subjects, the changes in R-R interval in ECG were evaluated (SKINOS MSD-001; SKINOS, Nagano, Japan) with a heart rate monitor (AD8232; Analog Devices, Norwood, MA, United States). The recording and ground electrodes of the ECG were fixed on the skin surface at thorax and upper extremity of human subjects, respectively.

For HRV testing, electrocardiographic (ECG) measurements were performed twice daily, in the morning and evening, using a sensor for ECG measurements [29 ]. Before measurement, the participants relaxed for at least 15 min, and AD8232 (Analog Devices) sensor chips with a 200 Hz sampling frequency were attached to both wrists and the right ankle to obtain the ECG readings [30 ]. Based on the obtained signal, HRV analysis was performed using MATLAB software (MathWorks, USA).