Structuring BaTiO₃ /PDMS Nanocomposite via Dielectrophoresis for Fractional Flow Reserve Measurement

Abstract

This work focuses on the development of piezoelectric sensors for the fractional flow reserve (FFR) technique, a procedure based on the measurement of blood pressure within a vessel to evaluate the severity of coronary stenosis. Considering the medical application, biocompatibility is a mandatory requirement that justifies the selection of fillers and matrix. Two composites made of lead‐free barium titanate nanoparticles (BaTiO3) incorporated in polydimethylsiloxane (PDMS) elastomer are developed: the first composite with particles randomly dispersed and the second one with particles aligned along one direction, via an innovative technique known as dielectrophoresis. The experimental characterization indicates that the electroactive and dielectric properties are coherent with the models’ prediction, confirming that the alignment of the filler gives rise to considerably enhanced dielectric and piezoelectric proprieties relative to the random dispersion. Thermal stability together with X‐ray diffraction is conducted, demonstrating superior piezoelectric response of the structured sample under high‐temperature conditions. FFR application is then simulated by applying an arterial pulse‐shape stimulus on the developed sensor, which is finally integrated into a catheter and directly inserted in a simulation arm.

Dielectrophoresis Structurization of PZT/PDMS Micro-Composite for Elastronic Function: Towards Dielectric and Piezoelectric Enhancement

“…Moreover, the distribution of the phases determines the local field intensity, and therefore provokes a certain polarization. In structured composites, for instance, the distribution of the electric field reveals to be more favorable and as a result it allows greater polarization [25,43]. In a composite, the electric field usually concentrate in the polymer matrix rather than in the filler, due to the lower dielectric properties of the polymer.…”

“…However, in 1-3 configuration, the electric field focuses mostly on the polymer gaps between the particles, making polarization of ferroelectric particles significantly enhanced. In 0-3 connectivity, using the same electric field as in the case of 1-3 counterpart is not sufficient enough to reach the most optimized polarization [25,43].…”

“…Their main advantage would be that, placed permanently on a structure, they could allow an online monitoring during the service life [19][20][21]. Piezoelectric composite sensors are also widely used in the medical fields for high frequency ultrasound imaging, in infusion, insulin pumps, respiratory monitoring, in blood pressure monitoring equipment and surgical fluid management systems [22][23][24][25][26][27][28].…”

“…The arrangement of the phases, named as connectivity, determines the performance of these composites. Different possible arrangements of the phases can be exploited to tailor the piezoelectric properties of the composites [25,29]. It is thus possible to design a proper structure within the material to enhance the efficiency of the sensor [1,30,31].…”

“…1-3 connectivity can be designed through several techniques such as rod placement, dicefill, ultrasonic cutting, laser machining, co-extrusion, tape lamination, and fiber insertion method [3]. Among the various existing methods, electric field structuration via dielectrophoresis emerges as a promising process: an electric field is applied to the sample before (at ambient temperature) and during the curing process (at high temperatures) in order to drive the particles into a columnar structure [25,34,[36][37][38]. The high temperature applied in the second stage of the process fixes the build-up design.…”