Electrically tunable soft solid lens inspired by reptile and bird accommodation.

Electrically tunable lenses are conceived as deformable adaptive optical components able to change focus without motor-controlled translations of stiff lenses. In order to achieve large tuning ranges, large deformations are needed. This requires new technologies for the actuation of highly stretchable lenses. This paper presents a configuration to obtain compact tunable lenses entirely made of soft solid matter (elastomers). This was achieved by combining the advantages of dielectric elastomer actuation (DEA) with a design inspired by the accommodation of reptiles and birds. An annular DEA was used to radially deform a central solid-body lens. Using an acrylic elastomer membrane, a silicone lens and a simple fabrication method, we assembled a tunable lens capable of focal length variations up to 55%, driven by an actuator four times larger than the lens. As compared to DEA-based liquid lenses, the novel architecture halves the required driving voltages, simplifies the fabrication process and allows for a higher versatility in design. These new lenses might find application in systems requiring large variations of focus with low power consumption, silent operation, low weight, shock tolerance, minimized axial encumbrance and minimized changes of performance against vibrations and variations in temperature.

Polymer based interfaces as bioinspired 'smart skins'.

This work reports on already achieved results and ongoing research on the development of complex interfaces between humans and external environment, based on organic synthetic materials and used as smart 'artificial skins'. They are conceived as wearable and flexible systems with multifunctional characteristics. Their features are designed to mimic or augment a broad-spectrum of properties shown by biological skins of humans and/or animals. The discussion is here limited to those properties whose mimicry/augmentation is achievable with currently available technologies based on polymers and oligomers. Such properties include tactile sensing, thermal sensing/regulation, environmental energy harvesting, chromatic mimetism, ultra-violet protection, adhesion and surface mediation of mobility. Accordingly, bioinspired devices and structures, proposed as suitable functional analogous of natural architectures, are analysed. They consist of organic piezoelectric sensors, thermoelectric and pyroelectric sensors and generators, photoelectric generators, thermal and ultra-violet protection systems, electro-, photo- and thermo-chromic devices, as well as structures for improved adhesion and reduced fluid-dynamic friction.

Electroactive polymer-based devices for e-textiles in biomedicine.

This paper describes the early conception and latest developments of electroactive polymer (EAP)-based sensors, actuators, electronic components, and power sources, implemented as wearable devices for smart electronic textiles (e-textiles). Such textiles, functioning as multifunctional wearable human interfaces, are today considered relevant promoters of progress and useful tools in several biomedical fields, such as biomonitoring, rehabilitation, and telemedicine. After a brief outline on ongoing research and the first products on e-textiles under commercial development, this paper presents the most highly performing EAP-based devices developed by our lab and other research groups for sensing, actuation, electronics, and energy generation/storage, with reference to their already demonstrated or potential applicability to electronic textiles.

A new method for quantitative cellular imaging on 3-D scaffolds using fluorescence microscopy.

This paper presents a new image processing technique for estimating cell numbers and contours in three-dimensional (3-D) microfabricated scaffolds. The method is based on a statistical approach, and utilizes the extreme value theory, which assumes that cells in the image field are rare, high-intensity events. Confocal microscopy images of fibroblasts on 3-D structures were processed using the method, and the resulting data on cell numbers was compared with countings obtained using a Burker chamber. The results were identical to within a few percent.

Enabling variable-stiffness hand rehabilitation orthoses with dielectric elastomer transducers.

Patients affected by motor disorders of the hand and having residual voluntary movements of fingers or wrist can benefit from self-rehabilitation exercises performed with so-called dynamic hand splints. These systems consist of orthoses equipped with elastic cords or springs, which either provide a sustained stretch or resist voluntary movements of fingers or wrist. These simple systems are limited by the impossibility of modulating the mechanical stiffness. This limitation does not allow for customizations and real-time control of the training exercise, which would improve the rehabilitation efficacy. To overcome this limitation, 'active' orthoses equipped with devices that allow for electrical control of the mechanical stiffness are needed. Here, we report on a solution that relies on compact and light-weight electroactive elastic transducers that replace the passive elastic components. We developed a variable-stiffness transducer made of dielectric elastomers, as the most performing types of electromechanically active polymers. The transducer was manufactured with a silicone film and tested with a purposely-developed stiffness control strategy that allowed for electrical modulations of the force-elongation response. Results showed that the proposed new technology is a promising and viable solution to develop electrically controllable dynamic hand orthoses for hand rehabilitation.

Electroactive polymer patches for wearable haptic interfaces.

Fully wearable and unobtrusive sensing will enable the possibility of monitoring people anywhere and anytime, for healthcare, well-being, protection and safety. Many research groups have exploited textiles as the ideal platform for pervasive monitoring. This paper reports advances in electroactive polymer technology oriented to mechanical sensing and actuation within textile interfaces. The preliminary development of a textile-based glove in which electroactive polymers act as force/position sensors and haptic feedback actuators is presented.

Electroactive elastomeric haptic displays of organ motility and tissue compliance for medical training and surgical force feedback.

This paper presents a novel approach used to develop haptic displays of motility of organs and compliance of tissues, aimed at combining structural simplicity with realistic appearance and consistence. The dielectric elastomer actuation technology was used to mimic mechanical passive properties and electromechanical active functions of tissues by means of electroresponsive elastomeric devices. Proof-of-concept displays were conceived for medical training in cardiology and surgical force feedback in minimally invasive procedures. In particular, prototype displays of cardiac contractility, pulsatile blood pressure, and compliance of soft tissues were manufactured with silicone and acrylic elastomers. Preliminary physical and psychophysical tests suggested the feasibility of the considered approach, while emphasizing required improvements.

Wearable kinesthetic systems and emerging technologies in actuation for upperlimb neurorehabilitation.

Kinesthetic and haptic interfaces between humans and machines are currently under development in a truly wearable form, using innovative technologies based on electroactive polymers. The integration of electroactive polymeric materials into wearable garments is becoming a viable mean to confer the garment strain sensing and actuation properties. In this paper, the implementation and testing of fabric-based wearable interfaces for the upper limb endowed with spatially redundant strain sensing are reported. Electroactive polymer actuators, which we are currently investigating, are discussed with emphasis given to their unique capabilities in the phenomenological mimicking of skeletal muscle actuation and control. Finally, current work in preliminary evaluation of prototypes in the field of post-stroke rehabilitation is also briefly presented.