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Table 2 Principal technical performance characteristics of implantable sensors for hearing devices

From: A technical review and evaluation of implantable sensors for hearing devices

Sensor type

ID

Bandwidth (kHz)

Sensitivity (dB ref. 1 mV/Pa)

SNR (dB ref. 1 mV/Pa)

EIN (dB SPL)

Power consumption (mW)

Subcutaneous mic.

A1

0.1–10

5

0.05–0.5a

Subcutaneous mic.

A2

0.2–6

− 10

0.05–0.5a

Subcutaneous mic.

A3

0.25–5

0.05–0.5a

Subcutaneous mic.

A4

0.1–8

35

0.05–0.5a

Electromagnetic sensor

B

0.25–3

− 30

37

57

\(\approx\) 1

Optical sensor

C

0.5–10

− 46b

6.4

Piezoresistive MEMS accelerometer

D

0.9–7

6c

40

63

> 1

Capacitive MEMS displacement sensor

E1

0.5–5

20

55

60

\(\approx\) 4.5

Capacitive MEMS displacement sensor

E2

0.8–8

30

70

34

\(\approx\) 4.5

Capacitive MEMS accelerometer

F1

0.2–6

19

35

35

\(\approx\) 4.5

Capacitive MEMS accelerometer

F2

0.5–6

− 9d

70

24

Capacitive microphone

G

0.1–10.0

28

18

29

\(\approx\) 1

Piezoelectric force transducer

H1

0.5–10

45

Piezoelectric force transducer

H2

0.25–8

Piezoelectric force transducer

H3

0.4–4

− 15

60

20

Piezoelectric accelerometer

I

0.25–10

1

52

38

0.12e

Piezoelectric MEMS accelerometer

J1

0.5–2.5

62b

Piezoelectric MEMS accelerometer

J2

0.3–6

20

50

44

0.01

  1. aPower consumption of ECMs for hearing aids (diaphragm diameter 2.5–10 mm) [6, 46]
  2. bCalculated with 0.34 mm/s/Pa, from the umbo velocity transfer function at 1 kHz  [74]
  3. cSensitivity of 0.02 V/\(g_0\) obtained from a similar piezoresistive sensor  [17]
  4. dTypical capacitive sensitivity is \(1\times 10^7\,\text {mV/m}\) [75]
  5. eData for preamplifier LMV1032, \(60\,\upmu \text {A}\) current, 2 V voltage supply [76]