Florinda Schembri

Microfluidic circuits and systems

The possibilities envisioned by the characterization of microfluidic systems cover a wide range of both scientific demands and industrial requirements, from life sciences to fine chemistry, from food quality to other microbiology applications. In these fields, the development of analytical methods and technological solutions oriented to the creation of a firm and structured link between models and experimentation on microfluidic systems, opens up the way for the study and characterization of microfluidic devices and phenomena from a point of view related to system and control theory.

A polymeric micro-optical interface for flow monitoring in biomicrofluidics

We describe design and miniaturization of a polymeric optical interface for flow monitoring in biomicrofluidics applications based on polydimethylsiloxane technology, providing optical transparency and compatibility with biological tissues. Design and ray tracing simulation are presented as well as device realization and optical analysis of flow dynamics in microscopic blood vessels. Optics characterization of this polymeric microinterface in dynamic experimental conditions provides a proof of concept for the application of the device to two-phase flow monitoring in both in vitro experiments and in vivo microcirculation investigations. This technology supports the study of in vitro and in vivo microfluidic systems. It yields simultaneous optical measurements, allowing for continuous monitoring of flow. This development, integrating a well-known and widely used optical flow monitoring systems, provides a disposable interface between live mammalian tissues and microfluidic devices making them accessible to detectionprocessing technology, in support or replacing standard intravital microscopy.

Computational modeling of droplet based logic circuits

The microfluidic universal computation has been simulated based on two-phase fluid flow at low Reynolds number using Computational Fluid Dynamics based on phase field numerical approach for investigation on spatial fluid dynamics. The presence or the absences of a bubble dispersed in a continuous liquid phase represent a bit ‘1’ or ‘0’ respectively. The working principle is based on the change in hydrodynamic resistance for a channel containing droplets.

Correlation between Spatial and Temporal Chaotic Behaviour in Two-Phase Microfluidics

Abstract In this work spatial and temporal nonlinear dynamics in microfluidics two-phase phenomena are investigated. Numerical models of two phase air/water flows in serpentine mixer were implemented exploiting a commercial CFD solution for investigation of spatial fluid dynamics inside air bubbles in the two-phase flow. Experimentation in microfluidic channels was also performed, time series were extracted from recorded images of two-phase (air and water) flow in a microfluidic serpentine mixer and nonlinear analysis methods were applied for time series characterization. Relationships between spatial parameters related to the direction of simulated fluid trajectories inside the air bubble and the largest Lyapunov exponents related to the bubbles’ temporal dynamics in experimentation were explored to characterize spatio-temporal patterns in microfluidics.

Nonlinear Dynamics in Experimental Two-Phase Microfluidics Timeseries

Abstract In this work experimental studies on nonlinear dynamics in two phase microfluidics were carried out. Nonlinear analysis methods were applied to time series coming from experimentation in microfluidics. The time series were captured using high sensitive photodiodes on a magnified image of the microfluidic phenomena under investigation, and they represent the time domain dynamics of a two phase flow in an in vitro serpentine mixer, in particular of bubbles flow patterns. This study allows capturing significant chaotic features in the time domain for different experimental conditions, and it is useful for a first understanding of two phase flow patterns in complex microchannels.

The Role of Input Flows in Microfluidic Experimentations

Abstract In this paper we discuss the role of input flow to control the dynamics of air bubbles carried by water in a snake micro-mixer. In particular it was proved the importance of flow rate magnitude and frequency to accomplish the desiderated bubbles’ flow dynamics. Time series coming from microfluidic experimentation were analyzed by means of nonlinear measures (Largest Lyapunov exponent and divergence analysis) in order to obtain quantitative indicators of nonlinearity allowing the classification among different flow patterns.