Design and Packaging of a Custom Single-lead Electrocardiogram (ECG) Sensor Embedded with Wireless Transmission

An embedded device is developed to acquire an electrocardiogram (ECG) signal by using only a single lead. The device is capable to capture the ECG signal of a human from the wrist or heart region and transmit data through Bluetooth low energy (BLE). The device includes a custom printed circuit board (PCB) for ECG acquisition. The custom PCB implements the AD 8232 chip for ECG calculation. The PCB is embedded with a commercial nRF52840 development board. Analog data from custom PCB is converted to the digital domain by using a 10-bit analog to digital converter (ADC) and transmitted through Bluetooth 5.3 both supplied by the development board. nRF52840 is 32 bit ARM
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Cortex™ processing unit. The BLE data is transmitted by a baud rate of 115.2 kbps. The PCB is 2-layer (32 mm X 50 mm X 4 mm). The device is powered by a 350 mA-hr LiPo battery and consumes approximately 0.58 mA of current. With this current consumption, the battery would last around 603 hours. Finally, all parts are packaged in a box to make it compact and functional for body-worn uses. The device is a low-cost, low-weight design suitable for mobile health (mHealth) applications.