Tushar Ghosh

Tushar Ghosh joined the faculty at NC State University after receiving his Ph.D. and has since been a visiting professor at the University of Sydney and the Indian Institute of Technology at Bombay. Currently, he is the William A. Klopman Distinguished Professor of Textiles at the Wilson College of Textiles at NC State.

Ghosh has been teaching various technology courses at both graduate and undergraduate levels. In recent years he has taught courses on weaving technology, functional textiles, and characterization of textile materials. Ghosh has served as a consultant to many public institutions and industries on issues related to textile technologies and the performance of textile products. He has authored several book chapters and monographs, over 100 journal articles and over 150 conference presentations.

Research Interests

His research activities are devoted to the technologies of fabric formation, mechanics of fiber assemblies and their characterization, and fiber-based structures for adaptive and responsive textiles. His current interests include the fabrication of sensors and actuators involving polymer nanocomposites, electroactive polymers, artificial muscle, and biomimetic systems.

Examples of Recently Completed and Current Research Projects

Functionally Tailored Textiles: 3-D Structures Through Melt Blown Technology: The research is aimed at developing the appropriate technology necessary to produce three-dimensional molded garments to produce low-cost combat uniforms with effective barrier characteristics, using minimal joining. The system being developed is called Robotic Fiber Assembly and Control (RFAC) system. RFAC system will allow the incorporation of fibers, powders, or other appropriate additives into the garment systems. The additives may identify, measure, absorb, and/or deactivate chemical/biological agents. In the RFAC system deposition of melt-blown fibers on an appropriate mold is controlled by a six-axis industrial robot. The system allows precise control of fiber orientation distribution, fiber diameter distributions, and pore size distribution.

Woven Fabric-based Electrical Circuits (Electro-textiles): Fabric-based electrical circuits are fundamental to electronic textile products of the future. The objective of the current research is to develop fabric-based electrical circuits by interlacing conducting and non-conducting threads into woven textile structures for civilians as well as military applications. Wired interconnections between different devices attached to the conducting elements of these circuits are made by weaving conductive threads so that they follow desired electrical circuit designs. In a woven electrically conductive network, routing of electrical signals is achieved by the formation of effective electrical interconnects and disconnects. Resistance welding is identified as one of the most effective means of producing crossover point interconnects and disconnects.  These circuits are evaluated for signal integrity issues (crosstalk, etc.). Two new thread structures – coaxial and twisted Pair copper threads to minimize cross talk have been developed and evaluated. Significant reductions in crosstalk were obtained with the coaxial and twisted pair thread structures when compared with bare copper thread or insulated conductive threads.

Development of Fiber Actuators:  Fiber actuators are capable of dimensional change under the applied electrical field. Dielectric elastomer-based prototype fiber actuators have been developed using commercially available dielectric elastomer tubes and by applying appropriate compliant electrodes to the inner cavity and outer walls of these tubes. The force and displacement generated by such actuators have been studied under different isometric conditions and as a function of the applied electric field. The actuation characteristics such as axial strains, radial strains, and actuation blocking forces produced in the prototype upon actuation were studied. Actuation strain and blocking force are strongly influenced by the applied prestrain and have a parabolic relationship to the applied electric field. High actuation strains (>50%) are currently afforded by dielectric elastomers at relatively high electric fields (>50 V/µm). A new class of electroactive polymers, suitable for fiber formation, has been developed by incorporating low-volatility, aliphatic-rich solvent into a nanostructured triblock copolymer yielding physically crosslinked micellar networks that exhibit excellent displacement under an external electric field. Ultrahigh areal actuation strains (>200%) at significantly reduced electric fields (<40 V/µm) have been achieved.

Electroactive Nanostructured Polymers as Tunable Actuators: Lightweight and conformable electroactive actuators stimulated by acceptably low electric fields are required for emergent technologies such as micro-robotics, flat-panel speakers, micro air vehicles and responsive prosthetics.1,2 High actuation strains (>50%) are currently afforded by dielectric elastomers at relatively high electric fields (>50 V/µm). In this work, we have developed a nanostructured copolymer blend that yields a physically cross-linked micellar network and exhibits excellent displacement under an external electric field. Such property development reflects reductions in matrix viscosity and nanostructural order, accompanied by an enhanced response of highly polarizable groups to the applied electric field. These synergistic property changes result in ultrahigh areal actuation strains (>200%) at significantly reduced electric fields (<40 V/µm). The use of nanostructured polymers whose properties can be broadly tailored by varying copolymer characteristics or blend composition represents an innovative and tunable avenue to reduced-field actuation for advanced engineering, biomimetic and biomedical applications.

Design, Characterization, and Processing of Carbon Nanofiber-Modified PVC as Fabric Sensor Composites for E-Textiles: The research aims to use screen-printing to fabricate an elastic and conductive nanocomposite layer of Plastisol, plasticized poly(vinyl chloride) (PVC), and carbon nanofiber (CNF) on textile fabrics to produce a piezoresistive strain-sensing substrate. The fabric sensor composite (FSC) being developed is based on the hypothesis that an elastomeric layer containing conducting nanoparticles printed on fabric substrates can yield a flexible, piezoresistive coating that can be tailored for specific applications. The research marries the demonstrated utility of plastisol as a print medium with the novelty of CNF-based polymer nanocomposites as applied to FSCs designed for use in electronic textiles. Previous studies have repeatedly identified benefits of CNFs relative to their CNT analogs, but relatively few studies have focused on conformable nanocomposites containing CNFs. The work seeks to establish a fundamental understanding of the physical factors governing CNF dispersion, percolation and subsequent mobility (upon drying) in a solvated polymer system (plastisol print medium) as a necessary prerequisite to the rational development of the target FSC. Insight into the percolation behavior of CNFs embedded in plastisol and subsequent property evolution will help to elucidate and further optimize the piezoresistive behavior of the FSC. Thus far, the percolation threshold of the plastisol-CNF was observed to be at ~2wt% and that the concentration of CNF where the resistivity starts to saturate is observed to be at 5wt%. Another significant observation is the increase of about 8 orders of magnitude in the conductivity of the composite when the concentration of the CNF was increased from 2wt % to 5wt %.

Education

Honors and Awards

• Outstanding Teacher of the Year, National Textile Center
• Circle of Excellence, National Textile Center
• 2007 | Founders Award, Fiber Society