SmartSphincter – biomimetic implant to treat fecal incontinence T. Töpper, B. Osmani, F. Weiss, E. Fattorini, M. Dominietto, V. Leung, S. Hieber, T. Brusa, P. Büchler, D. Abler, L. Brügger, C. Gingert, F. Hetzer, D. Bachmann, M. Held, U. Sennhauser, and B. Müller Annual Plenary Meeting nano-tera.ch Kursaal Bern, May 4, 2015
Fecal incontinence
External sphincter muscle M. Puborectalis Internal sphincter muscle
Fecal incontinence
External sphincter muscle M. Puborectalis Internal sphincter muscle
Causes • • •
Anatomical Neurological Injuries: birth trauma, hemorrhoids…
• •
Global: ~10 % of the population in Western countries CH: 42 % of men, 49 % of women, aged: 65+, nursing home
H-D. Becker, A. Stenzl, D. Wallwiener and T. Zittel: Urinary and Faecal Incontinence, SpringerVerlag, Berlin Heidelberg (2005)
Fecal incontinence treatments Stimulator unit
Gracilis Ischial tuberosity
Non-invasive
Invasive
• • • •
• • • •
Food - diet Medication Diapers Anal plug
Sphincter repair Sacral nerve stimulation Dynamic graciloplasty Stoma
Fecal incontinence treatments Stimulator unit
Gracilis Ischial tuberosity
Non-invasive
Invasive
• • • •
• • • •
Sphincter repair Sacral nerve stimulation Dynamic graciloplasty Stoma
•
Artificial sphincter
Food - diet Medication Diapers Anal plug
Actuation principles
Actuation principles
Project overview
I
Clinical study
Biomechanical model
II Smart nanostructures
Biomimetic actuator
III Electronics
Autonomous system
Data analysis
Clinical study
Biomechanical Model MRI
FLIP
US
Morphology
HRM
Mechanics
FEM MRI – Magnetic Resonance Imaging US – Ultra Sound FLIP – Functional Luminal Imaging Probe
HRM – High Resolution Manometry FEM – Finite Element Method
Clinical study Part I – Healthy subjects • • • •
10 females and 10 males Age > 60 years Averaged weighted BMI of 20-30 No surgical intervention in the pelvic floor
• •
High-resolution MRI probe MRI additionally combined with FLIP
• •
HRAM in 3D US 3D data
Clinical study IAS Part I – Healthy subjects • • • •
10 females and 10 males Age > 60 years Averaged weighted BMI of 20-30 No surgical intervention in the pelvic floor
• •
High-resolution MRI probe MRI additionally combined with FLIP
• •
HRAM in 3D US 3D data
Coil EAS
Clinical study IAS Part I – Healthy subjects • • • •
10 females and 10 males Age > 60 years Averaged weighted BMI of 20-30 No surgical intervention in the pelvic floor
• •
High-resolution MRI probe MRI additionally combined with FLIP
• •
HRAM in 3D US 3D data
Coil EAS
Clinical study IAS Part I – Healthy subjects • • • •
10 females and 10 males Age > 60 years Averaged weighted BMI of 20-30 No surgical intervention in the pelvic floor
• •
High-resolution MRI probe MRI additionally combined with FLIP
• •
HRAM in 3D US 3D data
Part II - Patients Planned
Coil EAS
Artificial muscles based on dielectric elastomer actuator (DEA)
1’000 to 10’000 layers
U ≤ 42 V
From micro- to nanometer silicone films
Start of operation: June 2015
Challenge: Stretchable electrodes Sputtering of Cr
Releasing the strain Height
! B. Osmani et al.: Micro- and nanostructured electro-active polymer actuators as smart muscles for incontinence treatment, AIP Conf. Proc. 1646 (2015) 91-100
Challenge: Stretchable electrodes
!
C. Winterhalter, Fabrication and four-point electrical characterization of nanometer-thin gold layers on a soft polymer (2014), Master thesis, ETH Z端rich physics department
Challenge: Stretchable electrodes 30 nm Au
10 nm Au
0
10
20
Strain [%]
T. Tรถpper et al., Strain-dependent characterization of electrode and polymer network of electrically activated polymer actuators, Proc. of SPIE 9430, 9430XX (2015)
Challenges for electronics • Cantilever microstructure: 16 mm x 4 mm • EAP thickness = 2.1 µm, dielectric constant: 2.8 Ø Capacity = 1.6 nF
• Charge transfer = 90 % • Autonomous sensor and actuator
Power consumption DEA
Consumption at VBat
DEA voltage
36 V
DEA10 cycles / day
0.635 mAh
Work per cycle (Exp)
658 mJ
Electronics operation / day
14.3 mAh
Recovered work / cycle
0 mJ
Electronics stand by / day
15.2 mAh
El. Charge / cycle
0.0635 mAh
Total / day
≈ 32 mAh
• Battery capacity = 325 mAh à 10 days without recharging • Life time = 80 % of it`s initial capacity: minimal 1000 recharging cycles à > 20 years until reoperation
Applications of low-voltage, nanometer-thin DEA • Fecal and urinary incontinence • Actuators and sensors within the human body • Tactile displays often termed artificial skin • Hinge-less devices in robotics incl. grippers and wipers • Flow control in micro- and nano-fluidics (lab-on-a-chip)
R. Pelrine et al.: High-speed Electrically actuated elastomers with strain greater than 100 %, Science 287 (2000) 836-839
Collaborative initiative of clinics, academia, and industry