## 3 Results
### Characterization of the Multisource Harvesting Section Integrated into the Smart Jacket  
This subsection presents the characterization results of the multisource harvesting sections integrated into the smart jacket in the operating modalities described in Section 2.3. Figure 17 summarizes the power generated by the multisource energy harvesting section in the five different scenarios previously described. Five different tests were conducted for each scenario with a 30 min observation interval; the current values absorbed by the electronic load were acquired and recorded using a portable data-logger (model PM8236, manufactured by Shenzhen Huayi Peakmeter Technology Co., Shenzhen, China) with a 30 s sampling time interval. The maximum power generated by the multisource harvesting  
Figure 16: Screenshots of the Serial Bluetooth Terminal with the connection status and the packet streams. system was calculated using the acquired time-domain trends. The mean maximum power (P\({}_{\text{Max}}\)) values for each scenario are shown in Figure 17, along with the maximum power generated by the multisource harvesting system, which are calculated using the acquired time-domain trends. Figure 18 depicts the distributions of the mean extracted power for the three different harvesting subsystems in the five tested scenarios. The measurements were performed by connecting a digital multimeter in series to each harvesting section (model PM8236). Therefore, the photovoltaic harvesting section contributes the most to the electrical power stored in the battery when the garment is directly exposed to sunlight (scenarios 1-2, Figure 18). However, due to the continued contributions of the thermal and piezoelectric harvesting subsections, it allows the continuous charge of the 380 mAh LiPo battery even in dispersed illumination (scenario 3) or artificial light (scenarios 4-5). As evident from the experimental results reported above, the energy contribution provided by the piezoelectric harvesting section is significantly lower compared to the thermal  
Figure 17: Maximum and mean power provided by the multisource harvesting section equipped in the wearable device as a function of the operating conditions. Figure 18: Histogram showing the energy distributions for the three different harvesting subsystems in the five considered scenarios. (a factor 11) and mainly photovoltaic (777) ones. However, in this research application, we chose to integrate the thermal contribution with the piezoelectric one, which contributes in all situations where no light sources are available, while also considering the reduced invasiveness of the developed transducers (Figure 4). According to the results of the harvesting system tests, scenario 2 requires roughly 4 h of charging time to completely charge the 380 mAh LiPo battery (Figure 17). As described in Section 3.2, the device's operating cycle includes the acquisition, processing, and transmission phase and lasts 40 s; after that, the sensing section goes to sleep for 15 min and then restarts for another cycle. In contrast, fall detection is entrusted to an interrupt for the MCU generated by the inertial module (MMA8452Q), triggering an ISR, with a consequent warning message transmitted to the cloud app. Additionally, tests on the electronic section demonstrate that in power-down mode, the mean absorbed current is 255.91 mA (I\({}_{\text{sleep}}\)), whereas, in active mode, it is only 7.51 mA (I\({}_{\text{active}}\)).