Project leader: Dr. Nicoleta Preda
Post-doctoral researcher: Dr. Andreea Costas
Post-doctoral researcher: Dr. Alexandru Evanghelidis
Post-doctoral researcher: Dr. Marcela Socol
Post-doctoral researcher: Dr. Irina Zgura
Experienced researcher: Dr. Monica Enculescu
Doctoral student: Drd. Daciana Botta

The project is focused on designing bio-inspired semiconducting fibers using natural polymers as bio-templates, further these semiconducting webs being integrated as fiber networks or as single fibers in field effect transistors (FETs) devices which can be applied in chemical sensing area. Thus, using eggshell membranes (ESM) and electrospun egg albumen (EA) as bio-templates,
semiconducting fibers based on metal oxides or/and metal sulfides (as monocomponents or as composites) will be prepared by immersion, electrospinning and calcination techniques. The obtained bio-inspired semiconducting fibers will be characterized by morphological, structural and optical point of view. Further, FETs based on semiconducting fiber networks and FETs based on single semiconducting fibers will be fabricated by combining physical deposition techniques (radio frequency magnetron sputtering, thermal vacuum evaporation) and lithography techniques (photolithography, electron beam lithography). Finally, the electrical performance of the FETs will be investigated after their exposure to various chemical vapours for evaluating the potential
applications of these devices in the chemical sensing field. The strategy used in the preparation of the bio-inspired semiconducting fibers can be regarded as a bio-inspired solution for fabricating electronic devices from renewable sources.

Stage I

The objective of the first stage - designing bio-inspired semiconducting fibers with specific properties involved the following experimental activities: i) obtaining EA webs with fiber structure by electrospinning and their characterization; ii) preparing semiconducting fibers using ESM and electrospun EA as bio-templates; iii) complex characterization of semiconducting fibers. The FESEM images evidenced that only few fiber structures were formed by electrospinning of egg albumen. In order to optimize the electrospinning process for achieving fiber webs, the solutions were prepared using polymers, which favour the formation of fiber-type structures and commercial albumin powder from eggs. The XRD, FTIR, TG, DTA and DSC investigations emphasized that the eggshell membranes, the powder obtained by drying the egg albumen and albumin powder from eggs have similar structural, vibrational and thermal properties. The influence of the experimental parameters (polymer type, solvent type, polymer concentration, protein concentration, humidity from the electrospinning chamber) on the morphological and structural properties of the electrospun protein fibers were evaluated by FESEM and FTIR measurements. Also, the influence of the bio-template origin on the replication process was analysed by using eggshell membrane (collagen) and flax fibers (cellulose) in obtaining an anorganic one based on zinc oxide fibers. The FESEM images and the XRD patterns showed that the specific architecture of each organic template was perfectly replicated in an anorganic one based on zinc oxide fibers. Further, the preparation of webs based on semiconductor fibers was achieved by: i) immersing the membranes in precursor solutions containing metal salts and further their calcination and ii) electrospinning the solutions containing polymer, albumin and metal salts and further their calcination. The thermal treatments were carried in different atmospheres (air, nitrogen, argon). The influence of the experimental parameters (bio-template type, metal salt type, calcination atmosphere) on the morphological, compositional and structural properties of the obtained inorganic webs was assessed by FESEM, EDX and XRD. Thus, the FESEM and the EDX images revealed a fiber-web morphology with an uniform distribution of component elements while the XRD patterns evidenced the formation of compounds such as semiconductor, metal:semiconductor or metal. In addition, the possibility to transform a metal oxide (zinc oxide) into metal sulfide (zinc sulphide) through a chemical reaction was evaluated, the XRD data proving the viability of this approach. The scientific results were disseminated in 1 article published in ISI journal (Q1) and 2 scientific communications (poster type) at international conferences.

Papers published in ISI journals:

1.Hierarchical flax fibers by ZnO electroless deposition: tailoring the natural fibers/synthetic matrix interphase in composites
Preda^*, A. Costas^*, F. Sbardella, M. C. Seghini, F. Touchard, L. Chocinski-Arnault, J. Tirillo, F. Sarasini
Nanomaterials, 12, 2765-15, 2022

Scientific communications at international conferences:

1.Bio-templated synthesis of interwoven fibers based on ZnO and ZnS by replicating eggshell membranes
A. Costas^*, N. Preda^*, M. Socol^*, I. Zgura^*, I. Enculescu
RICCCE 22 – 22nd Romanian International Conference on Chemistry and Chemical Engineering, 7-9 September 2022, Sinaia, Romania
Poster (abstract no. 36)

2.Bio-inspired fiber webs based on metal oxides by replicating eggshell membranes
A. Costas^*, N. Preda^*, A. Evanghelidis^*, M. Enculescu^*, I. Enculescu
12th International Advances in Applied Physics & Materials Science Congress & Exhibition (APMAS), 13-19 October 2022, Oludeniz, Turcia
Poster (abstract no. 2144)

^*project team members