# Strategic Development of Piezoelectric Nanogenerator and Biomedical Applications
## 4 Biomedical Applications
### Health Monitoring  
The use of PENGs contributes significantly to self-powered health monitoring devices. The integration of PENGs with health-monitoring sensors can be used to overcome the existing limitations related to powering healthcare devices.  
[PERSON] et al. [126] fabricated a PENG based on a metal phenolic coordination framework (MPCF) and a polymer composite. The composite comprised copper oxide nanosphere-tannic acid (CuO-TA) and copper-tannic acid (Cu-TA) nanocube-based MPCF and PVDF. A 2 \(\times\) 2 cm MPCF composite film was sandwiched between two copper electrodes, and the entire assembly was encapsulated in PDMS to fabricate the device. They compared the output of two different composites (CuO-TA/PVDF and Co-TA/PVDF) and observed a huge difference in performance. The CuO-TA/PVDF and Cu-TA generated output voltages of 40.20 V and 8.90 V, with currents of 4.40 \(\upmu\)A and 3.80 \(\upmu\)A, respectively. The device was used for the physiological monitoring and harvesting of biological energy. Assuming the condition of increasing heart disease, the authors utilized the CuO-TA/PVDF-based PENG as a physiological monitor and claimed that heart attacks are preventable if symptoms, such as real-time heart rate and arterial pulse [127], can be monitored. To investigate its efficiency and workability, the fabricated device was attached to a 22-year-old healthy person and their heart rate was monitored before and after exercise; the recorded values were approximately 76 and 145 BPM, respectively. The comparison of the results with values measured on a commercially available device suggested that the results were quite accurate. This indicated the sensitivity and applicability of the fabricated device. Furthermore, the authors linked PENG to the IoT to improve its application performance; this allowed the user to access their pulse rate remotely from anywhere. All the fabricated devices were flexible, self-powered, and sufficiently sensitive to distinguish between normal and accelerated pulse rates. This makes PENGs suitable for application in several health monitoring applications. Another attempt was made to develop a wireless self-powered hearth sensor. [PERSON] et al. [128] demonstrated the fabrication of a self-powered, auto-operated wireless sensor based on porous carbon, as shown in Figure 11A(a-c). The fabricated PENG was highly reliable, thus rendering it suitable for different applications, even in inconsistent environments. An output current of 22 \(\upmu\)A and a peak-to-peak voltage of 84.5 V were realized; in addition, the fabricated device was environmentally friendly. An entire self-powered network was built for sensing purposes, as shown in Figure 11A(d).  
Figure 11: (**A**) Wireless sensor based on a porous PVDF-based PENG. (**a**) Functional component of the fabricated sensor, which was made up of porous PVDF-PENG and an integrated circuit unit.  
**(b)** Actual image of the fabricated device. (**c**) Actual image of a fabricated porous PVDF device. (**d**) Block diagram of the entire sensing system [128]. Adapted with permission from [PERSON] et al. (2020) Copyright (c) 2020 American Chemical Society (**B**) Graphical representation of implant in a rat. (**a**) In vivo electrical simulator in a rat based on a PHBV/PLLA/KNN film nanogenerator with the combined use of ultrasound to enhance peripheral nerve repair [129]. Adapted with permission from [PERSON] et al. (2022). Copyright (c) 2022 Elsevier.