Smartsphincter

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