# Flexible Wearable Heart Rate Monitoring System and Low-Power Design: A Review
## 3 Design of the Flexible Wearable Heart Rate Signal Acquisition Module
### Hardware-Algorithm Co-Design of Flexible Wearable Heart Rate Signal Acquisition Module
These implementations collectively validate that combining low-power hard ware components such as ASICs and nRF52832 with intelligent algorithms such as compressive sensing and Huffman coding can systematically address the trade-offs among sampling resolution, data transmission, and energy efficiency. As evidenced by the \"high sampling rate-efficient compression-low-power\" feedback mechanism, hardware-algorithm co-design has become an indispensable strategy for promoting next-generation wearable medical devices to balance technical feasibility and energy sustainability. The Table 2 lists the innovativeness, practicality, power consumption optimization methods, power consumption levels, and comparisons of power consumption with previous studies for each technology, as shown in Table 2. Meanwhile, since the two methods mentioned in the algorithm aspect are relatively similar, only one of them is included in the table. It is worth noting that the literatures [42; 63; 68; 80; 81] all focus on research related to flexible wearable systems. In conclusion, this section systematically demonstrates the multi-dimensional strategies for achieving low-power operation in flexible wearable heart rate signal acquisition modules through hardware design, algorithm design, and hardware-algorithm joint design. In terms of hardware design, self-powered materials such as PVDF and piezoelectric ceramics are selected, the circuit structure is optimized, and multi-sensor collaboration is implemented,and a trade-off analysis is conducted between the low power consumption achieved based on the self-powered nature of materials and that achieved through circuit optimization. In algorithm design, energy consumption is reduced by optimizing the sampling rate and dynamically adjusting the acquisition time. More importantly, in hardware-algorithm co-design, the deep integration of hardware selection and algorithm innovation significantly reduces the module's power consumption. These comprehensive solutions not only balance the power consumption and performance of the module but also pave the way for the widespread application of energy-efficient flexible wearable heart rate monitoring systems. \begin{table}
\begin{tabular}{p{42.7 pt} p{56.9 pt} p{56.9 pt} p{56.9 pt} p{56.9 pt} p{56.9 pt}} \hline \hline
**Reference** & **Innovation** & **Practicality** & \multicolumn{2}{c}{**Power Optimization Method**} & \multicolumn{1}{p{56.9 pt}}{**Power Consumption**} & \multicolumn{1}{p{56.9 pt}}{**Power Comparison**} \\ \hline
[42] & An ultrathin sensor based on electronic tatto technology. & Achieve non-invasive and continuous physiological information monitoring. & Hardware & 3 mW & Compared with traditional ECG sensors, the power consumption is reduced by more than 40\%. \\ \hline
[81] & The first standalone skin-like patch integrating a stretchable OLED array with a PPG sensor. & Achieve non-invasive and continuous physiological information monitoring. & Hardware & 16.5 mW & N/A \\ \hline
[68] & An optimal sampling rate optimization algorithm is proposed. & Reduce storage costs and extend device battery life. & Algorithm & N/A & Compared with traditional algorithms, the adaptive optimal sampling rate algorithm reduces system power consumption. \\ \hline
[63] & The first application of compressed sensing technology to a PPG-specific integrated circuit. & Achieve ultra-low power consumption, suitable for clinical research in health monitoring. & Hardware-Algorithm co-design & 1.66 mW & Reduction of about 57\% Compared with previous reports, the power consumption has been reduced by approximately 57\%. \\ \hline \hline \end{tabular}
\end{table} 
Table 2: Key references comparison of innovations, practicality, power consumption optimization methods, power consumption and power consumption comparison with other similar work of regarding heart rate signal acquisition module in flexible Wearable Heart Rate Monitoring System.