Table 4 Comparison of the proposed instrument with commercial (portable and implantable) wireless biopotential acquisition systems
Parameters | TMSI Mobita | TMSI Mobi | Activa PC + S | This work |
|---|---|---|---|---|
Number of channels | 32 | 6 (+ 4) | 2 | 5 (+ 3) |
Type of biosignals | ExG, body position and movement | ExG, (+ temperature, respiration, body position and movement) | LFP/ECoG | ExG, ECoG, LFP, ERNA, body position and movement, PV ectopic activity (+ amperometric/potentiometric) |
Supply of the ADC | ±2 V | ±2 V | 1.7–2.2 V | ±2.5 V |
Voltage gain | 20 dB | 26 dB | 48–66 dB | 60 dB |
Input voltage range | ±200 mV | ±100 mV | ±500 μV to ±4.4 mV (for 2.2 V supply) | ±2.3 mV |
Maximum available bandwidth | DC up to 0.13 × sample frequency | – | 0.5–260 Hz | 0.5–500 Hz |
Input impedance | > 100 MΩ | > 100 MΩ | – | 200 GΩ |
Input referred noise | < 0.4 μV rms (0.1–10 Hz) | < 1 μV rms | < 1 μV rms | 0.169 μV rms (0.5–500 Hz) |
DC tolerance | – | – | – | ±85 mV |
CMRR | > 100 dB | > 90 dB | > 80 dB | 134 dB |
Maximum resolution of the ADC | 24 bits | 24 bits | 10 bits | 24 bits |
Maximum sampling frequency | 2000 SPS | 2048 SPS | 422 SPS | 1 kSPS (32 kSPS for wired) |
Hours of continuous operation | 6 to 8 (4.1 Ah lithium battery) | - (2 AA batteries) | – | 8 (1 Ah lithium battery) |
Wireless capability | Yes (Wi-Fi) | Yes (Bluetooth) | Yes (175 kHz near-field inductive) | Yes (Zigbee) |
Area (length × width) | 105 cm2 | 112 cm2 | 39 cm2 | 44 cm2 (PCB area) |