At the boundary of the matter

Pyro-EHD printing

A new opto-nanofluidic approach named Pyro-EHD (pyro-electrohydrodynamic) was developed for dispensing liquid nano-pico-droplets through pyroelectric effect activated by hot tip source or an IR laser into a dielectric crystal using a non-invasive simple and powerful electrode-less configuration [1]. Local pyroelectric forces draw liquid droplets from the reservoir below the substrate, and deposit them on the underside of the lithium niobate substrate. The shooting direction is altered by moving the hot tip or laser to form various patterns at different angles and locations. This system does not require electrodes, nozzles or circuits, and has many applications in biochemical assays and various transport and mixing processes. Moreover, extending the use of the pyro-dispenser also to high viscous polymer, we are able to print regular but long wave forms of instability, such as beads-on-a-string, and also well-ordered fibers patterns with uniform diameter and regular geometry in real time[4].

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a, Liquid is dispensed onto a translating substrate inserted between the LN and the glass plate. b, Side view of the typical printing functionality. c-d Tipical curved and dotted patterns obtained by means of the pyro-EHD dispenser; e. printing of ordered  fibers pattern

 

 

Responsabile della commessa: Simonetta Grilli

Collaboratori commessa: Veronica Vespini, Sara Coppola, Oriella Gennari, Laura Mecozzi, Michele Todino, Federico Olivieri

[1] Nature Nanotechnology 5,429–435(2010) DOI:10.1038/nnano.2010.82

[2] Lab Chip, 2011,11, 3294-3298 DOI: 10.1039/C1LC20472F

[3] Lab Chip, 2011 Sep 21;11(18):3148-52. DOI: 10.1039/c1lc20326f

[4] Chemistry of Materials, 06/2014; DOI: 10.1021/cm501265j

 

Non-conventional 3D lithography

Unsteady liquid structures, shaped in polymeric liquids by an electrohydrodynamic pressure, can be rapidly cured by appropriate thermal treatments. We have developed a unique but straightforward approach that exploits instabilities and self-assembling of polymeric liquids for fabricating single or arrays of complex high aspect-ratio 3D microstructures [1]. Liquid instabilities are first driven via EHD pressure and then quickly cured to obtain permanent 3D microstructures, by the same thermal treatment, paving the way to a previously undescribed “3D lithography concept/platform,” in which nanoliquid instabilities could be “fluidynamically” designed a priori with the aim at fabricating even more complex shapes exploitable in many fields.

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Magnified view of beads-on-a-string structures, oblate microspheres, and side view of typical BOAS with satellite and subsatellite beads

 

 

 

Collaboratori commessa: Veronica Vespini, Sara Coppola

[1] Proc Natl Acad Sci U S A. 2011 Sep 13; 108(37): 15106-15111  DOI:  10.1073/pnas.1110676108

 

Drawing polymer microlenses by pyroEHD effect

In the recent years many commercial applications such as optoelectronics, photonic and biomedical devices, as well as image processing require the fabrication of adaptive and adjustable micro-lens arrays. The application of a pyro-electrohydrodynamic (Pyro-EHD)-dispenser for this purpose, overpasses the viscosity limit of the conventional ink-jet printing systems, working in a nozzle-less modality. This method represents a simple alternative to the conventional soft lithography techniques. A thin layer of liquid polymer is deposited on a micro-engineered ferroelectric crystal and can be self-assembled and cross-linked in a single step process as a consequence of the pyro-electric effect activated by simply heating the substrate. Such microlenses can be useful also as polymer patterned arrayed microstructures for optical data interconnections, OLEDs efficient light extraction, concentrating light in energy solar cells, imaging and 3D display solutions and other photonics applications.
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Optical microscopy images of the PDMS periodic arrays:microlenses and microdonuts for different RPM values.

Collaboratori commessa: Veronica Vespini, Sara Coppola, Vito Pagliarulo, Oriella Gennari, Laura Mecozzi, Michele Todino, Federico Olivieri

[1]IEEE Journal of Selected Topics in Quantum Electronics 11/2014; DOI: 10.1109/JSTQE.2014.2367656

[2]Proc. SPIE 9130, Micro-Optics 2014, 91300B (May 2, 2014); DOI:10.1117/12.2052832

[3] Langmuir vol.24, 13262 (2008).

 

Non-conventional solar energy harvesting

The use of pyro-electricity for solar energy harvesting has been widely investigated over the past years. Recently, a novel device able to harvest solar energy by means of an optical system focusing solar radiation onto a ferroelectric crystal (i.e. lithium niobate-LN) has been developed [1]. The presence of the polymer absorber (carbon black-CB) coating for the LN crystal is decisive for two reasons. First of all to increase the amplitude of temperature variation experienced onto the crystal, that greatly exceeds the one obtained without any layer. Moreover, the most important aspect to focus on, is the achievement of a wider spectral absorbance. In fact, thanks to the CB coating with a higher absorbing coefficient and a wider spectral absorbance with respect to the lithium niobate pyro-electric crystal (transparent from 320 to 5000 nm), the whole visible and IR wavelengths of solar radiation are involved in the energy harvesting (1000-1200 nm for standard solar cells).

 

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Thermal map of the pyro-electric element with CB coating

Collaboratori commessa: Veronica Vespini, Sara Coppola, Laura Mecozzi

[1] Applied Energy , Graphene and carbon black nano-composite polymer absorbers for a pyro-electric solar energy harvesting device based on LiNbO3 crystal,. 12/2014; 136:357-362. DOI: 10.1016/j.apenergy.2014.09.035

 

Interaction of living cells with ferroelectric crystals

The effects of ferroelectric spontaneous polarization on cell behaviour were investigated by cell cultivation on c-cut LN crystals. The overall results demonstrate that the LN crystals can be definitely used as an innovative platform for manipulating cells thorough the effects of the spontaneous polarization, thus opening the way to the development of new principles that can be used for tissue-engineering applications. Moreover, compared to standard biomaterials, this kind of platform could provide revolutionary integrated functionalities thanks to the unique richness of properties that can be exploited into a single material such as LN, including photorefractivity, pyroelectricity and optical nonlinearity.

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Confocal microscope images of cells plated on c- and c+ face, with nuclei, actin and vinculin stained with DAPI, TRITC-conjugated phalloidin and DyLight488 vinculin, respectively

Cells_2015 (1)

Collaboratori commessa: Valentina Marchesano, Oriella Gennari, Laura Mecozzi

 

Experimental and computational neuroscience

 The neuronal functionality is studied by using patch-clamp electrophysiology and computational methods. The cellular and molecular processes involved in the signaling of neuronal and sensorial cells are investigated for the understanding their basic properties and responses to electrical, chemical (drugs) and photonic stimulations.

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(a) Currents registered using patch-clamp techniques;(b) Computed EPSC and EPSP

Collaboratori commessa: Silvia Santillo, Vito Di Maio

 [1]Vito Di Maio, Francesco Ventriglia and Silvia Santillo (2015) A model of dopamine modulated glutamatergic synapse, Biosystem; http://dx.doi.org/doi:10.1016/j.biosystems.2015.05.001

[2]Santillo S., A. Schiano Moriello and V. Di Maio (2014) Electrophysiological variability in the SH-SY5Y cellular line, General Physiology and Biophysics 33(1), ISSN: 0231-5882; DOI: 10.4149/gpb_2013071

[3]Musio C. and S. Santillo (2012) Non-Visual Photosensitivity and circadian vision. In: CRC Handbookof Organic Photochemistry and Photobiology, 3rd ed., A. Griesbeck, F. Ghetti & M. Oelgemoeller, Print ISBN: 978-1-4398-9933-5 eBook ISBN: 978-1-4665-6125-0,  DOI 10.1201/b12252-51

[4]Cristino L., V. Guglielmotti, A, Cotugno, C. Musio and S. Santillo (2008) Nitric oxide signaling pathways at neural level in invertebrates: functional implications in cnidarians, Behavioural Brain Research, 1225:17-25. ISSN: 0166-4328; DOI: 10.1016/j.brainres.2008.04.056

[5]Radilová J., C. Taddei-Ferretti, C. Musio, S. Santillo, E. Cibelli, A. Cotugno and T. Radil (2008) The effects of pattern shape, subliminal stimulation, and voluntary control on multistable visual perception, Behavioural Brain Research 1225:163-170. ISSN: 0166-4328; WOS: 000258954600015

 

Polymer pyro-electrification (PPE)

A novel polymer pyro-electrification (PPE) technique for the fabrication of polymer membranes with permanent periodic polarization was developed. The technique is surprisingly simple thanks to the use of spontaneous pyroelectric charges arising onto the PPLN crystal surface during the thermal treatment. The reliability of the PPE membranes is demonstrated for liquid dispensing and for cell patterning. The heat-free electrodynamic dispensing opens a new route in the field of liquid microscale manipulation of liquids under an electrode- and nozzle-free procedure and, in addiction,  the absence of a thermal stimuli allows to extend the technique to all applications where the thermal stimulus may be detrimental, especially in case of biological applications.

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Free standing electrified membrane in which is evident the selective adhesion of cells

Collaboratori commessa: Romina Rega, Oriella Gennari, Laura Mecozzi

 

Azopolymers – cells interaction

 Azopolymer materials belong to family special materials, which are subject to photo-isomerization when illuminated by appropriate light wavelength. Optical characterization of azopolymer materials is interesting because they can be patterned in an easy way when illuminated by coherent polarized light. The interference lithography (IL) is an excellent tool to trigger the isomerization reaction on the material realizing the so calling Surface Relief Gratings that have applications in the field of biotechnology, photonic elements, molding templates, etch masks and micro-nanochannels. In particular in the field of biotechnology, azopolymers are and biocompatible supports suitable to induce an on-off change in topographical signals allowing to study real time cell behavior. Our study is focused on NIH-3T3 cells on light-induced patterned azopolymers, concerning the study of the elongation, orientation and morphology of focal adhesions. Moreover, cell behavior was investigated on circularly polarized light erased azo-patterns in order to study biological feedback to photo-induced topographical changes.

ACS Cattura         am-2015-02080f_0008 (1)   imagin4

 Confocal images of NIH-3T3 cells on (A) flat surface, (B) 2.5×2.5 μm grid pattern, (C) 2.5

 Collaboratori commessa: Vito Pagliarulo, Maurizio Ventre, Alejandro Calabuig Barroso

Rianna et. al Reversible holographic patterns on azopolymers for guiding cell adhesion and orientation ACS Appl. Mater. Interfaces, DOI: 10.1021/acsami.5b02080

A. Calabuig “Imaging and characterization of surface relief gratings on azopolymer by digital holographic microscopy “, Proc. SPIE 9529, Optical Methods for Inspection, Characterization, and Imaging of Biomaterials II, 95290L –

 

Manipulation of microsized objects

A novel technique to grip and transport micrometre- sized targets under the action of an electric field pyroelectrically generated was developed. A sort of pyroelectric nanorobot that can be adapted for managing also liquids, that we name here as Pyroelectric-Adaptive-Nanorobot (PYRANA)[1]. This efficient kind of manipulation offers a lot of potential applications ranging from chemical to biomedical experiments. The object is gripped thanks to the electric forces and can be transferred from its initial location to any other one.  In particular the micro-object can be transferred and hold in correspondence of a liquid droplet reservoir thus allowing the delivering of nanoliter liquid drops on its surface.  The interesting aspect is that liquid dispensing is accomplished through an electrohydrodynamic pressure driven by the very same pyroelectric excitation adopted for the gripping operation that can be adopted in lab-on-chip devices and avoiding cross-contamination problems if pipettes, nozzles or mechanical tweezers are used.

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The liquid was dispensed on a moving micro-target.

 

Collaboratori commessa: Veronica Vespini, Sara Coppola

[1] Lab Chip, 2011 Sep 21;11(18):3148-52. DOI: 10.1039/c1lc20326f

 

Interplay between photorefractive electric fields and biological samples

Photorefractive (PR) properties of ferroelectric crystals are exploited to demonstrate electrode-free dielectrophoresis (DEP) of live biological samples. The PR effect in ferroelectric crystals generate surface evanescent electric fields able to trap and orient live object. In the recent years trapping of nanoparticles and polymer patterning has been largely investigated while PR interaction with biological sample has been studied to induce death in cancer cell cultures.

For the first time the interplay between PR fields and biological behaviours in living cells is going to be explored. We performed a comprehensive study to manipulate bacteria cells, maintaining them alive. In order to test the technique feasibility we study the interaction of Escherichia coli with the PR field generated on the surface of iron-doped lithium niobate. The experiments showed that about 80% of bacteria were blocked and oriented along a particular direction within an area of few square centimetres (Figure 1). PR DEP is completely induced by the interaction of light with the activable ferroelectric crystal, the work is in progress to investigate the light-shaping of more complex bio-processes as migration and duplication in adherent cells (Figure 2).

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Figure 1. (a) schematic representation of evanescent field and consequent E. coli orientation. (b) pictures of aligned bacteria on different grating periods and with different magnification. All scale bars are 20µm. (c) bacteria chains longer than 10µm aligned perpendicularly to the grating planes. (d) histograms representation of percentage E. coli alignment in case of in line configuration.

 

lisa 2

Figure 2.  Phase-contrast map, realized by Digital holographic microscope, of an adherent fibroblast  on the surface of LN crystal. PR effect is responsible of the electric field surface gradients and of the phase grating clearly visible by means of interferometric

People:

Lisa Miccio

Simonetta Grilli

Valentina Marchesano

Martina Mugnano

Alejandro Calabuig

 

Pubblicazione correlata:

Optics and Lasers in Engineering         http://dx.doi.org/10.1016/j.optlaseng.2015.03.025