1. Enabling new biomedical and bioinspired mechatronic systems with electroactive smart elastomers Federico Carpi 1

2. EAP are materials capable of changing dimensions and/or shape in response to suitable electrical stimuli (Stanford Research Institute) Example: dielectric elastomer actuator Electromechanically Active Polymers (EAP) 2

3. 3

4. thickness compression surface expansion Electrostatic pressure: p = ε 0 ε r E 2 Thin insulating elastomeric film sandwiched between two compliant electrodes:  4 Dielectric elastomer actuators

5. Thin film of insulating elastomer sandwiched between two compliant electrodes, so as to obtain a deformable capacitor. Electrical charging results in an electrostatic compression of the elastomer. Stanford Research Institute Pelrine, Kornbluh, Pei, et al. Dielectric elastomer actuators (our group) 5

6. How to use the DE actuation principle? Possibilities for new devices and applications limited only by imagination! The greatest value of this technology lies in the fact that it is extremely ‘poor’ (‘poor’ materials and extremely simple mechanism) 6

7. (Stanford Research Institute) (Our group) Dielectric elastomer actuators

8. Properties: 1)Inherently capable of changing dimensions and/or shape in response to suitable electrical stimuli, so as to transduce electrical energy into mechanical work. In that, they show attractive propeties as engineering materials for actuation: -efficient energy output, -high strains, -high mechanical compliance, -shock resistance, -low mass density, -no acoustic noise, -ease of processing, -high scalability -low cost. 2)Can also operate in reverse mode, transducing mechanical energy into the electrical form. Therefore, they can also be used as mechano-electrical sensors, as well as energy harvesters to generate electricity. 3) Capable of stiffness control. 4) Can combine actuation, sensing and stiffness control, not only in the same material, but actually in the viscoelastic matter they are made of, showing functional analogy with natural muscles artificial muscles Dielectric elastomer actuators

9. … artificial skeletal muscles … Not today Main challenges: - need for improved actuating configurations - need for higher energy density (natural muscle performance can be exceeded, but only in exceptional conditions) - need for lower driving voltages - mechanical interfaces with the body A dream in the biomedical field…

10. Compressive stress (Maxwell stress): ε 0 =8.854 pF/m: dielectric permittivity of vacuum E= applied electric field ε= relative dielectric permittivity of the elastomer Need for new high-permittivity elastomers: composites blends new synthetic polymers 1) FIRST APPROACH: increasing the material dielectric constant 2) SECOND APPROACH: reducing the film thickness V= applied voltage d= thickness Reducing the driving voltages 10

11. 1) Full-page refreshable and portable Braille displays for the blind people 2) Wearable tactile display for virtual interactions with soft bodies 3) Haptic or visual displays of tissue compliance or organ motility 4) Artificial ciliary muscles for electrically tuneable optical lenses for artificial vision systems 5) Artificial muscles for electrically stretchable membrane bioreactors Contributions from our group: Biomedical & bioinspired applications

12. 1) Full-page refreshable and portable Braille displays for the blind people 2) Wearable tactile display for virtual interactions with soft bodies 3) Haptic or visual displays of tissue compliance or organ motility 4) Artificial ciliary muscles for electrically tuneable optical lenses for artificial vision systems 5) Artificial muscles for electrically stretchable membrane bioreactors Contributions from our group: Biomedical & bioinspired applications

13. Artistic view of a possible Braille tablet/e-Book This is science fiction today! Full-page refreshable and portable Braille displays for the blind people

14. STATE OF THE ART Full-page refreshable and portable Braille displays for the blind people

15. STATE OF THE ART piezoelectric cantilever actuators Assembling two lines of Braille cells requires putting two series of actuators nose-to-nose, with their cantilevers pointing away from the cells, laterally 10 cm 3 cm > 20 cm Full-page refreshable and portable Braille displays for the blind people

16. STATE OF THE ART piezoelectric cantilever actuators 25-30 cm Thickness 3-4 cm Assembling two lines of Braille cells requires putting two series of actuators nose-to-nose, with their cantilevers pointing away from the cells, laterally Full-page refreshable and portable Braille displays for the blind people

17. F. Carpi, G. Frediani, D. De Rossi, “Hydrostatically coupled dielectric elastomer actuators”, IEEE/ASME Transactions On Mechatronics, vol. 15(2), pp. 308-315, 2010. OUR APPROACH: Bubble-like ‘hydrostatically coupled’ DE actuators Full-page refreshable and portable Braille displays for the blind people

18. Dielectric elastomer film: silicone (Elastosil RT625, Wacker) processed as a thin film by Danfoss PolyPower Film thickness: about 66  m (two films stacked together) Transmission medium: vegetable (corn) oil Max voltage: 2.25 kV Prototypes Full-page refreshable and portable Braille displays for the blind people

19. - Simple and compact structure; - Ease of fabrication (  low cost) - Electrical safety: i) passive end-effector (no need for insulating coatings) ii) dielectric fluid (as a further protection); - Self-compensation against local deformations caused by the finger: the shape and the thickness uniformity of the active membrane are preserved Attractive features for tactile displays: Full-page refreshable and portable Braille displays for the blind people

20. Refreshable Braille cell based on Hydrostatically Coupled DE actuators: External electrodes Internal electrodes TOP PASSIVE MEMBRANE BOTTOM ACTIVE MEMBRANE Plastic frame Braille dot Full-page refreshable and portable Braille displays for the blind people

21. Thickness 1-2 mm 4 cm 25-30 cm Thickness 3-4 cm Potential advantages over the state of the art: 1)Compact size 2)Suitability for ‘full-page’ displays 3) Light weight 4) Shock tolerance 5) Low cost state of the art Refreshable Braille cell based on Hydrostatically Coupled DE actuators: Full-page refreshable and portable Braille displays for the blind people

22. Prototype samples Elastomer film: 3M VHB 4905 acrylic polymer. Bi-axial pre-stretching: 4 times. Pre-stretched thickness: about 30 µm. Electrode material: carbon conductive grease. Transmission medium: silicone grease Refreshable Braille cell based on Hydrostatically Coupled DE actuators: Full-page refreshable and portable Braille displays for the blind people

23. Early prototype with Braille dots and spacing oversized (up-scaled) with respect to standards. Refreshable Braille cell based on Hydrostatically Coupled DE actuators: Full-page refreshable and portable Braille displays for the blind people

24. Braille dot with standard size (diameter = 1.4 mm; height = 0.7 mm) Refreshable Braille cell based on Hydrostatically Coupled DE actuators: Full-page refreshable and portable Braille displays for the blind people

25. 1) Full-page refreshable and portable Braille displays for the blind people 2) Wearable tactile display for virtual interactions with soft bodies 3) Haptic or visual displays of tissue compliance or organ motility 4) Artificial ciliary muscles for electrically tuneable optical lenses for artificial vision systems 5) Artificial muscles for electrically stretchable membrane bioreactors Contributions from our group: Biomedical & bioinspired applications

26. Wearable tactile display for virtual interactions with soft bodies G. Frediani, D. Mazzei, D. De Rossi, F. Carpi, “Wearable wireless tactile display for virtual interactions with soft bodies”, Frontiers in Bioengineering and Biotechnology, Vol. 2, 2014.

27. Wearable tactile display for virtual interactions with soft bodies G. Frediani, D. Mazzei, D. De Rossi, F. Carpi, “Wearable wireless tactile display for virtual interactions with soft bodies”, Frontiers in Bioengineering and Biotechnology, Vol. 2, 2014.

28. Wearable tactile display for virtual interactions with soft bodies G. Frediani, D. Mazzei, D. De Rossi, F. Carpi, “Wearable wireless tactile display for virtual interactions with soft bodies”, Frontiers in Bioengineering and Biotechnology, Vol. 2, 2014. Video

29. 1) Full-page refreshable and portable Braille displays for the blind people 2) Wearable tactile display for virtual interactions with soft bodies 3) Haptic or visual displays of tissue compliance or organ motility 4) Artificial ciliary muscles for electrically tuneable optical lenses for artificial vision systems 5) Artificial muscles for electrically stretchable membrane bioreactors Contributions from our group: Biomedical & bioinspired applications

30. (dots: liver) (dots: stomach) Force feedback in minimally invasive surgery F. Carpi et al. IEEE Transactions on Biomedical Engineering, Vol. 56(9), pp. 2327-2330, 2009. Controlling the stiffness to simulate different tissues Haptic or visual displays of tissue compliance or organ motility

31. 31 (Control via EMG) (Control via respiration) (Control via ECG) Haptic or visual displays of tissue compliance or organ motility Medical training

32. 1) Full-page refreshable and portable Braille displays for the blind people 2) Wearable tactile display for virtual interactions with soft bodies 3) Haptic or visual displays of tissue compliance or organ motility 4) Artificial ciliary muscles for electrically tuneable optical lenses for artificial vision systems 5) Artificial muscles for electrically stretchable membrane bioreactors Contributions from our group: Biomedical & bioinspired applications

33. Artificial vision (computer vision) systems in the biomedical field: - Social robots (e.g. robot therapy) - Medical diagnostics (e.g. video endoscopes and other optical instrumentation, lab-on-a-chip units, etc.) - etc. Conventional optical focalization : focal length tuning achieved by displacing one or more constant-focus lenses.  moving parts  miniaturization is complex and expensive,  bulky structures Need for tunable-focus lenses with no moving parts Electrically tuneable optical lenses for artificial vision systems

34. F. Carpi et al., “Bioinspired tunable lens with muscle-like electroactive elastomers”, Advanced Functional Materials, 2011. Artificial ciliary muscles for electrically tuneable optical lenses

35. F. Carpi et al., “Bioinspired tunable lens with muscle-like electroactive elastomers”, Advanced Functional Materials, 2011. Artificial ciliary muscles for electrically tuneable optical lenses

36. F. Carpi et al., “Bioinspired tunable lens with muscle-like electroactive elastomers”, Advanced Functional Materials, 2011. Bioinspired lens Human crystalline Artificial ciliary muscles for electrically tuneable optical lenses

37. F. Carpi et al., “Bioinspired tunable lens with muscle-like electroactive elastomers”, Advanced Functional Materials, 2011. Artificial ciliary muscles for electrically tuneable optical lenses

38. F. Carpi et al., “Bioinspired tunable lens with muscle-like electroactive elastomers”, Advanced Functional Materials, 2011. 3 cm 10 cm Artificial ciliary muscles for electrically tuneable optical lenses

40. L. Maffli, S. Rosset, M. Ghilardi, F. Carpi, H. Shea, "Ultrafast all-polymer electrically tuneable silicone lenses", Advanced Functional Materials, in press. Artificial ciliary muscles for electrically tuneable optical lenses WORLD’S FASTEST AND THINNEST tuneable lens: settling time < 175 μs for a 20% change in focal length Low-loss silicone Be-spoke manufacturing Cooperation with EPFL (Prof. Herbert Shea’s group)

41. L. Maffli, S. Rosset, M. Ghilardi, F. Carpi, H. Shea, "Ultrafast all-polymer electrically tuneable silicone lenses", Advanced Functional Materials, in press. Artificial ciliary muscles for electrically tuneable optical lenses WORLD’S FASTEST AND THINNEST tuneable lens:

42. 1) Full-page refreshable and portable Braille displays for the blind people 2) Wearable tactile display for virtual interactions with soft bodies 3) Haptic or visual displays of tissue compliance or organ motility 4) Artificial ciliary muscles for electrically tuneable optical lenses for artificial vision systems 5) Artificial muscles for electrically stretchable membrane bioreactors Contributions from our group: Biomedical & bioinspired applications

43. SLIDES ON THIS PART HAVE BEEN REMOVED FROM THIS ONLINE VERSION OF THIS PRESENTATION, AS RESULTS ARE NOT PUBLISHED YET 43 Artificial muscles for electrically stretchable membrane bioreactors

44. Inustrialization of the dielectric elastomer technology is living its infancy nowadays… Dielectric elastomer actuators

45. Main EAP developers Today the EAP field is just starting to undergo transition from academia into commercialization (developers of transducers based on piezoelectric and electrostrictive polymers not included) EAP industrialization

47. European Scientific Network for Artificial Muscles (ESNAM) www.esnam.eu 68 Member organizations from 26 European countries:

48. Relevant website: “EuroEAP” www.euroeap.eu

49. ‘EAPosters’ ‘EAPodiums’ ‘EAProducts’ Relevant event: “EuroEAP conference” Annual International conference on Electromechanically Active Polymer (EAP) transducers & artificial muscles

50. Relevant event: “EuroEAP conference” EuroEAP 2015 Tallin, Estonia 9-10 June 2015 www.euroeap.eu EuroEAP 2011 - Pisa, Italy EuroEAP 2012 - Potsdam, Germany EuroEAP 2013 - Zurich, Switzerland EuroEAP 2014 - Linköping, Sweden