5.3 Biomimetic Acoustic Sensors

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Figure 5.8: A hair is incorporated into the bilayer interface, and electrodes are fed into each aqueous

phase, resulting in a sensitive flow sensor.

Figure 5.9: Artificial hair cells used as flow sensors (adapted from [16]).

Another flow sensor uses a silicon beam accompanied by a piezoelectric strain sensor

[16] (Figure 5.9). The sensor was mechanically stable even at a high flow velocity. This

artificial hair cell was also able to sense the flow direction and low frequencies in water.

In a different system, vibrations are not measured, but their energy is harvested to

create a “battery” for implanted devices such as pacemakers and deep brain stimulation

devices [17]. Conventional batteries are problematic for these devices because they are

bulky and have to be replaced regularly. It would be a lot more effective if an energy

source could be harvested that is already part of the body and could be used to power

these devices. To develop such a system, a film of a piezoelectric material on a flexible

substrate could be used, which allows the piezoelectric material to react to any bending

by generating an electric signal. Vibrations are sufficient to generate a signal, which