| Smart Materials |
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Scientific and technical research as well as technologically relevant applications of microstructured advanced materials have been steadily increasing during the past decades. The interest towards the development of microdevices and microrobots based on smart materials, especially those showing electromechanical response, has been driven by various motivations. Smartness is a feature typically referring to biological systems that are able to interact adaptively with the environment. The term “Smart” generally refers to those materials that, in response to an external stimulus or to changes in their surrounding conditions are able to reversibly modify one or more of their functional or structural properties. The external stimuli causing the smart response of the material could be of various kind: physical (temperature, light, electric or magnetic fields, etc.), chemical (pH, analyte concentrations in air, water, biological fluids), mechanical (stress, strain). It is intended that the process is fully reversible: smart material is capable of returning to its initial state as soon as the trigger (external stimulus) is removed. To cite some widely known examples of smart materials: shape memory alloys and polymers (respectively SMAs and SMPs) change their physical shape returning to a preset one in response to temperature variations, making them useful for actuation; nanostructured surfaces of some amphiphilic block copolymers change their surface properties from hydrophilic to hydrophobic (and/or viceversa) in response to changes in pH or in temperature; some classes of crosslinked polymers are able to self heal their own mechanical damages by self-restoring chemical bonds that have been cleavaged; piezoelectric materials are able to transduce mechanical deformations in electric voltages and viceversa; smart hydrogels are able to swell/deswell in response to change in pH and are applied in drug delivery systems; some chemoresponsive polymer nanocomposites are able to change their stiffness in presence of a chemical regulator, etc. Smart Materials have been introduced in microtechnology, for instance in the development of MEMS and NEMS devices, in order to achieve novel functionalities of microscopic devices such as sensing properties. Additionally they could also permit to power and control motion of microobjects via innovative approaches. Approaches Research Topics |