FIRB

Development of technologies for implementation of electronic components and devices on textile substrates
funded by the Italian Ministry of Education, University and Research)

The goal of this project is the implementation of tecnologies for building electronic structures on a textile substrate.
The possibility of designing active electronic devices integrated on a textile substrate allows to think of the same structure as a wearable system, or more generally as a system suitable for covering surfaces of whatever shape and able to elaborate electronic signals. Such technology has many applications in a variety of fields, such as biomedicine, sport, multimediality.
The need of mantaining the mechanical flexibility of textiles reduces the possible materials and technologies suitable for the aims of the project: electrical conductivity and its modulation cannot be obtained through traditional semiconductors (such as silicon and inorganic semiconductors). Necessarily there is the need for materials whose mechanical properties do not differ too much from those of textile substrates.
Conductive polymers, at present investigated in the field of molecular electronics, are the best candidates for accomplishing such needs.
After solving the problem of materials, suitable structures and architectures are to be studied. The problem is complex and the goal appears to be achievable in, at least, two ways: the electronically functionalized fabric can be obtained by depositing the selected materials on it, according to a predetermined geometry, or, the fabric can be obtained starting from a functionalized fiber. This project aims to explore both solutions. According to the first idea, deposition on fabric, the project will concern technologies, already availble for one the partners, which will be applied to the deposition of organic semiconductors on a textile. In particular, we will consider the use of microsyringes (pressure and/or volume controlled) and ink-jet heads for the deposition of polymers diluted in volatile solvents. Alternatively, the soft lithography approach to the deposition of geometrically defined structures on a surface will be explored. Such technique is applied, at present, both on planar substrates and on cilindrical surfaces. This allows to think also to the soft lithography functionalization of fibers. At the same time of the deposition technologies, we will consider the problem of designing proper structures according to their electronic functions. We will realize simple passive circuit elements, like resistors and capacitors, and we will explore the possibility of obtaining also active electronic devices, like field effect transistors. Several exemples of Thin Film Transistors have been successfully realized in the last years both on rigid substrates (like silicon) and on flexible substrates (polymeric). We will try to realize such a device on a fabric, which, if necessary, will be preliminarily covered by suitable layers for sake of homogeneity. Moreover, we will explore the possibility to obtain electronic active properties directly on a fiber. Parallel to the exploration of all possible deposition techniques, the assessment of electronic properties of the obtained structures and the maintainance of elasto-mechanical properties typical of a fabric will be always taken into primary consideration.

Left: longitudinal section of an electronic ribbon-like textile structure; Right: scheme of a woven fabric where the vertical lines are made by the textile ribbons and the horizontal are conductive wires that represent source and drain contacts.