Table 1 Design parameters for the UroSleeve with the integrated antenna and pressure sensor as well as the external reader antenna used – σ: internal residual stress, E: Young’s modulus, ν: Poisson’s ratio, ε: dielectric permittivity R: DC resistance, L: inductance, fr: reflectance peak of the external reader antenna

From: Ureteral stent sleeve for early detection of hydronephrosis

Parameter

Size [µm]

Relevant parameters

Tesla-valve enabled touch mode capacitive pressure sensor

Sensor chip

 Width

870

 

 Length

3200

 

 Substrate thickness

500

 

Sensor membrane

 

σ 26 MPa

 Radius

250

 

 Au thickness

2.85a

E 78 GPa, ν 0.44

 Ti adhesion layer thickness

0.02

E 116 GPa, ν 0.32

 Parylene C thickness

4.6

E 2.76 GPa, ν 0.40

Sensor gap (before deflection)

2.8

 

Sensor dielectric

 Sensor dielectric Si3N4 thickness

0.275

ε 9.7b

Tesla-valve channels

 

4 Channels/Cavity

 Overall length

178

 

 Overall width

420

 

 Channel entrance width

10

 

UroSleeve 9 loop spiral antenna

 

R 1.4 ohm, L: 1.97 µH @ 15.1 MHz, fr 18.1 MHz

 Length

50,000

 

 Outer spiral width

8270

 

 Inner spiral width

2110

 

 Cu Line width

200

 

 Cu Line thickness

70

 

 Polyimide substrate thickness

25

 

 Assembled bend curvaturec

2790

 

External reader 10 loop inductor

 

R 0.1 ohm, 4.5 µH @ 16.7 MHz, fr 28.5 MHz

 Overall length

50,000

 

 Overall width

8000

 

 Wire thickness

510.6

24-gauge magnetic wire

  1. aThe fabricated sensor had a 2.85-µm thickness based on FEM simulation to place the sensor in touch mode when the sensor cavity is under vacuum
  2. bThe constant was experimentally measured using the capacitance and the known surface area of characterization structures
  3. cThe curvature is based on the assembly of a 6-Fr double-J ureteral stent