Table 2.
List of transducing modalities with some of their associated sensing principles.
| SN | Transducer Category | Transducing Modality | Sensing Principles | |||
|---|---|---|---|---|---|---|
| Potential | Capacitive | Piezoelectricity | Piezoresistivity | |||
| 1.0 | Acoustic | PCG | - | * | Piezoelectric Accelerometer [171] |
- |
| Ultrasound | - | LZT Sensor [172] |
- | |||
| 2.0 | Electrical | ECG | Lead Electrode [173] |
CCEs [156] |
- | - |
| ICG | Lead Electrode [174] |
- | - | - | ||
| 3.0 | Electromagnetic | EM | - | PRF S-R Sensor [124] |
- | - |
| 4.0 | Mechanical | BCG | - | Electromechanical Film Sensor [167] |
- | - |
| SCG | - | - | MEMS Accelerometer & Gyroscope [168] |
|||
| TAG | - | Au/PEN [169] |
- | Flexible Piezoresistance [170] |
||
| 5.0 | Optical | PPG | - | - | - | DPP-DTT: PCBM [175] |
* Piezoelectric crystals appear electrically as capacitors (since they basically consist of two electrodes surrounding a dielectric material). However, at their resonant frequency they behave closer to a pure resistance.