aimed at controlling malfunction or restoring the lost functions of the body. Common

examples of such devices are pacemakers, retinal implants, prosthetic controllers, neuro-

stimulators, and cochlear implants. There have been several exciting developments from

then on, such as the integration of radio frequency identification (RFID) and near-field

communication microchips [2]. These features have been instrumental in monitoring in-

situ parameters of organs and transmitting information for rapid diagnostics and treat­

ment of ailments. However, a significant area that has challenged researchers is the power

sources in the form of traditional batteries that have poised as a drawback by limiting the

lifetime of such devices [1]. The limitations with the conventional batteries have affected

the miniaturization as well.

Consequently, when the batteries deplete, the patient needs to undergo revision sur­

gery to replace the current device with a new one, thereby increasing the risk of infections

resulting in deaths and, at the same time, the economic burden on the patient [3].

Therefore, there is a growing need for new power sources for biomedical systems’ in­

dependent and continuous operation. The idea is to implement smaller-sized micro­

electronic devices that can function with ultra-low power as an alternative to the existing

devices. However, the concerns about the power source remain. One option is to harness

the energy from the body movements that will power these biomedical devices [4]. This

process has altogether given rise to a new area of research that will harvest the energy

generated from the various body movements and ultimately complement as the power

source for the miniaturized biomedical devices. The devices thus developed will be

termed self-powered biomedical devices for in-vivo and ex-vivo applications.

To harness the energy generated from the movements in the body, several processes have

been identified, and different supporting mechanisms have been proposed for the same.

Fan et al. made a pioneering discovery by designing a piezoelectric nanogenerator (PENG)

and subsequently triboelectric nanogenerator (TENG) in 2006 and 2012, paving the way for

an alternative source of energy generation other than a conventional battery [5]. After that,

the pyroelectric nanogenerators (PyNG) and thermoelectric nanogenerators (TEG) were

designed to harvest the waste heat generated from the body. Significant developments

in nanogenerators (NGs) have articulated the concept of self-powered devices into

reality and, in its current state, have generated widespread interest due to its output

performances, cohesiveness in miniaturization, and most importantly, the biocompat­

ibility aspects [6]. This chapter is an attempt at understanding such technologies that

demonstrate the potential to power self-powered devices: a milestone of the current

state of development.

20.2 Survey of Power Requirements of Biomedical Devices

Portable electronic devices such as implantable radio transmitters, pacemakers, wearable

glucose monitors, and pressure sensors require voltages lesser than 100 mV, and the

power limits are lesser than 20 µW [4]. In Figure 20.1, we present an illustration that

shows a survey of power generated from various human body motions. The Figure

shows that harnessing about 1%–5% of the energy associated with the multiple move­

ments would be sufficient for powering the wearable biomedical devices. As shown in

Figure 20.1, the energy generated from the arms motion is enough to produce a point of

60 W, which is more than sufficient to power pacemakers [4]. In the current scenario, the

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Bioelectronics