**6. WPT in emerging biomedical topics**

WPT systems are rapidly evolving for biomedical implants, including emerging topics of implantable pacemaker devices, implantable optogenetic devices, and implantable impedance plethysmography (IPG).

**Figure 12.** *Circuit diagram of a class E power amplifier.*

*Wireless Power Transmission on Biomedical Applications DOI: http://dx.doi.org/10.5772/intechopen.103029*

**Figure 13.** *WPT system by (a) magnetic field coupling [27] and (b) electric field coupling for implantable applications [24].*

#### **6.1 Wireless charge-based implantable pacemaker**

Heart failure is one of the most killers worldwide. It occupies one-third of all global death. Nowadays, the implantable cardioverter pacemaker is a common approach to directly suppress heart failure [28, 29]. However, the battery life could cause health risks and patient inconvenience. Parinaz Abiri *et al.* [30] developed an inductively powered wireless pacing device to realize remote cardiac stimulation. They designed a Class E-based magnetic field resonant coupling system with a resonant frequency of 13.56 MHz to pace rhythm on Yucatan miniature pig.

#### **6.2 WPT-based implantable optogenetic device**

Optogenetics is an emerging field that provides an alternative for direct electrical stimulation to modulate membrane voltage. By genetic modification, the ion channels in the cell can be sensitive to certain wavelengths of light [31]. Nowadays, several advanced biomedical topics have involved the optogenetic topic in different applications, including neuroscience to control animal behavior [32, 33] and cardiology to find out a solution for cardiovascular disease [34, 35]. Yu *et al.* [36] implement an

implantable optogenetic device implanted into the dog's chest. WPT-based optogenetic modulation of cardiac sympathetic nerve activity can prevent ventricular arrhythmias.
