Hybrid ferroelectric-polymer microfluidic device for dielectrophoretic self-assembling of nanoparticles

Carbon nanoparticles are becoming ubiquitous in many fields of science and technology. However, a grand challenge remains in assembling, patterning, and positioning or even simple manipulation of CNTs for complex functional assemblies. CNTs have in fact enormous perspectives for application in biotechnologies as bactericide agents or as prominent tools for investigating cell mechanisms, or more in general as functionalized nanoparticle-vectors, but their exploitation requires viable technology at the lab-on-a-chip scale. Many approaches have been attempted in developing technologies for manipulating CNTs. One elective approach is based on electric fields driven mechanisms such as DEP forces. A variety of chips have been designed and realized with this aim. Here we report on a novel hybrid microfluidic chip made by assembling a polar-dielectric crystal with polymeric microfluidic channels. One challenging feature of such a hybrid device approach, based on an electrode-free dielectrophoretic (DEP) approach, is that it makes use of surface charge templates for self-assembling and manipulation of CNTs in liquid media directly into a microfluidic channel. Here various examples of self-assembly in microfluidic channels as well as separation and collection of two classes of nano/microparticles are reported. The method can open the way to novel fabrication protocols for the realisation of future flexible devices with new and more complex functionalities, highly desirable in electronics as well as in biotechnology at the lab-on-a-chip scale. 2014 The Royal Society of Chemistry

Electro-drawn Drug-Loaded Biodegradable Polymer Microneedles as a Viable Route to Hypodermic Injection

Hypodermic needle injection is still the most common method of drug delivery despite its numerous limitations and drawbacks, such as pain, one-shot administration, and risk of infection. Seeking a viable, safe, and pain-free alternative to the over 16 billion injections per year has therefore become a top priority for our modern technological society. Here, a system that uses a pyroelectric cartridge in lieu of the syringe piston as a potential solution is discussed. Upon stimulation, the cartridge electro-draws, at room temperature, an array of drug-encapsulated, biodegradable polymer microneedles, able to deliver into hypodermic tissue both hydrophobic and hydrophilic bioactive agents, according to a predefined chrono-programme. This mould-free and contact-free method permits the fabrication of biodegradable polymer microneedles into a ready-to-use configuration. In fact, they are formed on a flexible substrate/holder by drawing them directly from drop reservoirs, using a controlled electro-hydrodynamic force. Tests of insertion are performed and discussed in order to demonstrate the possibility to prepare microneedles with suitable geometric and mechanical properties using this method. Biodegradable polymer microneedles represent a promising tool in transdermal drug delivery field. Here, a new fabrication approach based on polymer solution electro-drawing is presented. Microneedles produced with this technique can be obtained directly onto flexible substrate with controlled shape and can indent epithelium layer of animal skin. Furthermore, microneedles can be loaded with both hydrophobic and hydrophilic active compounds

Reversible fragmentation and self-assembling of nematic liquid crystal droplets on functionalized pyroelectric substrates

Investigation on the behavior of nematic liquid crystals on functionalized polar dielectric crystal substrates is accomplished. Very interesting effects can be observed in maneuvering liquid crystal droplets on the substrate surface, driven by electric fields generated by pyroelectric effect. Reversible drops fragmentation and self-assembling in different configurations can be achieved. The dynamics of the observed phenomena is studied and the repeatability of the process is full assessed. �� 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim

Tethered Pyro-Electrohydrodynamic Spinning for Patterning Well-Ordered Structures at Micro- and Nanoscale

A study was conducted to demonstrate tethered pyro-electrohydrodynamic spinning (TPES) for patterning well-ordered structures at micro- and nanoscale. The TPES was introduced in wireless modality without electric circuit, electrodes, and voltage supply. This novel approach definitively simplified the electrospinning (ES) apparatus extending the nanofiber spinning to active organic polymers preserving at the same time all the properties of conventional systems. Fiber drawing from the liquid polymer was driven through the pyroelectric charge generated into a ferroelectric crystal able to induce the electrohydrodynamics (EHD) pressure required for polymer manipulation without wires. The approach was highly flexible, simple, compact, and cost-effective when compared with classical ES and allowed working safely, avoiding the use of high-voltage equipment at kVolts scale

Highly sensitive detection of low abundant molecules by pyro-electrohydro-dynamic jetting

The p-jet approach allows to obtain the dispensing of drops of very small volumes (up to tenths of a picoliter) avoiding the use of syringes and nozzles generally used in standard technologies. The reliability of the technique as a biosensor is demonstrated both in the case of oligonucleotides and in a sample of clinical interest, namely gliadin. The results show the possibility of detecting these biomolecules even when they are low abundant, i.e. down to attomolar. Moreover, it has been presented the possibility of using the p-jet as a useful tool in the detection of biomarkers, present in the blood but currently not detectable with conventional techniques and related to neurodegenerative diseases such as Alzheimer

Easy Printing of High Viscous Microdots by Spontaneous Breakup of Thin Fibers

Electrohydrodynamic jetting is emerging as a successful technique for printing inks with resolutions well beyond those offered by conventional inkjet printers. However, the variety of printable inks is still limited to those with relatively low viscosities (typically <20 mPa s) due to nozzle clogging problems. Here, we show the possibility of printing ordered microdots of high viscous inks such as poly(lactic-co-glycolic acid) (PLGA) by exploiting the spontaneous breakup of a thin fiber generated through nozzle-free pyro-electrospinning. The PLGA fiber is deposited onto a partially wetting surface, and the breakup is achieved simply by applying an appropriate thermal stimulation, which is able to induce polymer melting and hence a mechanism of surface area minimization due to the Plateau-Rayleigh instability. The results show that this technique is a good candidate for extending the printability at the microscale to high viscous inks, thus extending their applicability to additional applications, such as cell behavior under controlled morphological constraints