Table 1 Pressure-induced capacitance change.

From: Hydrogel microphones for stealthy underwater listening

Salt concentration (mM) MNP-free hydrogel MNP–hydrogel
  C 0 (nF) Δ C (nF) Δ C/C0 (%) Δ n/n (%) C 0 (nF) Δ C (nF) Δ C/C0 (%) Δ A/A (%)
10−2 0.94 0.05 5.3 10.9 3.45 0.83 24.0 17.7
1 6.38 0.3 4.7 9.6 15.625 2.5 16.0 10.8
10 15 0.6 4.0 8.2 36.67 4.4 12.0 7.7
100 81.5 2.2 2.7 5.5 170.73 14 8.2 5.4
1,000 312.5 5.0 1.6 3.2 476.2 10 2.1 0.5
  1. Note: all the values of C0, ΔC and ΔC/C0 showed here are the average values using three samples by performing one test on each sample.
  2. Ion concentration modulation (Δn/n) and deformable MNP (ΔA/A) in hydrogel capacitors contribute to capacitance variation under a static pressure of 5.4 kPa.