Table 3.
Parameter comparison of wireless sensing devices using inductive coupling
| Reference | Ratio of readout distance‐areaa) | Type | Readout distance [cm] | Sizeb) | R. freq.c) [MHz] | Quality factor | Induc‐tance [µH] | Area [mm2] |
|---|---|---|---|---|---|---|---|---|
| This work | 2.4 | Solenoid coil | 5.5 (air) | 15 mm (l), 7.5 mm (d), 0.1 mm (t) | 6.2 | 153 | 9.1 | 7.85 × 10−3 |
| (Park et al. 2016) | 0.4 | Planar coil in stent | 0.2 (air) | 3 × 3 mm2, 0.15 mm (t) | 200 | 10 | 0.839 | 2.25 × 10−4 |
| (Chen et al. 2014) | 3.8 | Planar, stacked coils | 1.5 (air) | 4 × 4 mm2, 0.1 mm (t) | 1000d) | – | – | – |
| (Chen et al. 2010) | 1.3 | Planar coil | 2 (air) | 4 mm (d) | 350 | 30 | 0.057 | – |
| (Brox et al. 2016) | 1.6 | Gold‐coated stent | 2.75 (air) | 20 mm (l), 5 mm (d) | 50.7 | 24 | 0.53 | 4.42 × 10−3 |
| (Fonseca et al. 2006)(Abbott 2017) | 2.9 | Planar, stacked coils | 20e) (air/implant) | 15 mm (l), 3.4 mm (w), 2 mm (t) | 30–50 | 65–77 | – | 2.88 × 10−3 |
a)
It defines the ratio of wireless readout distance and cross‐sectional area of the sensor. Our work shows the best performance among the reported inductive coupling methods
b)
Note that some references have limited information about the sensor size. Unit expression: length (l), diameter (d), width (w), and thickness (t)
c)
R. freq.: resonance frequency
d)
High frequency signals significantly attenuate in tissue and limit readout distance when implanted
e)
Achieved with double the system power used here.