speech recognition are a few examples of biomimetic sensors. This electronic skin has

been synthesized with different materials of different shapes. These sensors are fabricated

from a 3D electrode at the top and bottom for the detection of multidirectional forces. The

bottom electrode contains the microdermis on the bottom in the form of periodic arrays.

There are 25 capacitors in a single microdome arranged in the top, surrounding, corners,

and slope directions. These capacitors are used for quantitative analysis that responds to

the pressure experienced by different strains. This non-uniform sensor provides a more

accurate evaluation of the applied force because each sensing pixel experiences the

characteristic pressure and responsive curve [20]. The electrolytes also plays important

role in biomimetic sensors and measure the induced dynamic and static pressure. An

applied pressure generated the piezo potential that induces the movement of ions

through electrolytes. The induced flow of ions generates the piezoelectric signals. Thus,

dynamic and static signals are measured simultaneously. In some biomimetic devices,

piezoelectric and triboelectric effects have been induced, collectively. The electronic skin

inspired by the fingerprint (Figure 9.2) contains both of these phenomena. The signals

TABLE 9.1

Comparisons of Different Parameters Between Human Skin and Some Sensors Type

Active material

Sensitivity

Detection range

Response time/

frequency

Mechanism

References

PVDF/ZnO

0.33 V kPa⁻¹

1–30 kPa

16 ms

Piezoelectric

[ 10]

AgNWs/Rose petal

1.54 kPa⁻¹ (<1 kPa)

0.0006–115 kPa

–

Capactive

[ 11]

Human skin

–

0–110 kPa

0.005–0.4 kHz

Biosensing

[ 12]

Au/m-PDMS

15 kPa⁻¹ (<0.1 kPa)

<4 kPa

<100 ms

Resistive

[ 13]

m-PDMS

150 kPa⁻¹ (<0.2 kPa)

0.005–1 kPa

–

Triboelectric

[ 14]

FEP/Au

112.4 mV dB⁻¹

50–100 dB

0.1–50 kHz

Triboelectric

[ 15]

AgNWs/PU

26.07 (0.6%)

0%–80%

–

Resistive

[ 16]

TPU/IL

23.3 V kPa⁻¹

<50 kPa

–

Triboelectric

[ 17]

CNT-PDMS

9617 (90%–120%)

0%–120%

10 ms

Resistive

[ 18]

PTNWs/Graphene

9.4 × 10⁻³ (G.F)

<1.5 kPa

5–7ms

Piezoelectric

[ 19]

FIGURE 9.2

Biomimetic skin with triboelectric and piezoresistive layers. Adapted with permission [ 21]. Copyright 2019,

American Chemical Society.

Bioinspired Prosthetic Interfaces

143