Antonio Affanni

EV battery state of charge: neural network based estimation

Different electric vehicles (EV) types have been developed with the aim of solving pollution problems caused by the emission of gasoline-powered engines. Environmental considerations promote the adoption of EV for urban transportation. As it is well known one of the weakest points of electric vehicle is the battery system. Vehicle autonomy and therefore accurate detection of battery state of charge are among the main drawbacks that prevent the spread of electric vehicles in the consumer market. This paper deals with the analysis of battery state of charge: performances of a few sizes of batteries are analyzed and their state of charge is estimated with a neural network (NN) based system. The obtained results have been used to design a lithium-ion battery pack suitable for electric vehicles. The proposed system presents high capability of energy recovering in braking conditions, together with charge equalization, over and under voltage protection. Moreover a neural network based estimation of battery state of charge has been implemented in order to optimize autonomy instead of performances or vice-versa depending on journey.

Design and characterization of magnetostrictive linear displacement sensors

The design of a low-cost, linear position sensor, based on the transmission of ultrasonic signals in a magnetostrictive delay line is presented. The paper analyzes the sensor principle, parameters to be optimized, conditioning circuits as well as sensor characterization, comparing the results with commercial sensors.

Electrical Impedance Spectroscopy on flowing blood to predict white thrombus formation in artificial microchannels

The “in vitro” study of white thrombus growth by means of Electrical Impedance Spectroscopy on whole blood is presented; the aim of the work is to correlate thrombus formation in an artificial channel with impedance measurements. The measurement bench is composed of a sensor, a switch unit and an impedance meter. Post process of measured data is performed and an equivalent lumped circuit is derived; experimental data are obtained with a first prototype based on a single couple of electrodes.

A Discrete Geometric Approach to Cell Membrane and Electrode Contact Impedance Modeling

This paper presents a novel discrete model for cell membranes and electrodes contact impedances alternative to the widely used finite elements. The finite element approach can be considered as a tool for constructing finite dimensional systems of equations that approximate the specific electroquasistatic biological problem on the discrete level. Although the finite element technique is explained typically in terms of variational or weighted-residual approaches, another, less familiar way is available to reformulate geometrically the same physical problem. This approach, referred to as discrete geometric approach, allows a direct link between geometry and the degrees of freedom describing the specific biological problem. It is straightforward to implement in any finite element open software and it assures a correct modeling of voltages and currents playing a fundamental role in a biological problem. The validation has been performed, as a first step, against analytical solutions; then, we considered impedance measurements regarding erythrocytes in whole blood flowing in microchannels at high shear rates.

Combined Electro-Optical Imaging for the Time Evolution of White Thrombus Growth in Artificial Capillaries

We present a novel methodology to measure white thrombus volume growth in an artificial microchannel, where whole blood flows. We designed a sensor consisting of a poly-dimethyl-siloxane microchannel and parallel gold electrodes sputtered on the surface of a slide, where induced hemostasis takes place. A novel inversion methodology, based on optical and electrical impedance data simultaneously processed, allows reconstructing the thrombus volume. The advantage of the proposed methodology is to reconstruct the evolution of the thrombus volume as a function of time; this is not possible with the present state of the art optical imaging based on confocal microscopy, which provides the thrombus volume estimation only at the end of the process.

Numerical Modelling and Experimental Study of an AC Magnetohydrodynamic (MHD) Micropump

This paper describes the working principle and provides FEM simulations and some experimental results of an AC magneto-hydrodynamic micropump. The pump, without moving parts, operates at low-frequency, medium-high AC magnetic fields without gas bubble formation and produces a continuous flow. Therefore, it is in principle compatible with biological samples in a miniaturized total analysis system (muTAS). A preliminary prototype was realized with low cost material in order to verify the results provided by finite element simulation. Flow velocities up to 22 mm/s at an applied current density at the electrodes of 8 kA/m2 and a magnetic field of 70 mT have been demonstrated for a channel section of 6.5 mm2 in very good agreement with simulations and theory

A Novel Inversion Technique for Imaging Thrombus Volume in Microchannels Fusing Optical and Impedance Data

The aim of this paper is to present a novel inversion technique to measure the volume of thrombus induced under blood flow conditions in a lab-on-a-chip device. The device is composed by a microscope slide where gold electrodes are sputtered and by a polydimethylsiloxane microchannel placed on the top of the slide. A thrombogenic substance is placed on the slide in such a way that hemostasis is induced when whole blood flows in the microchannel. The novel idea behind the inversion technique is to fuse optical and electrical impedance data to obtain a quasi-real-time reconstruction of thrombus volume. This is not possible with present state-of-the-art optical imaging based on confocal microscopy, which provides the thrombus volume estimation only at the end of the thrombus formation.

Ex vivo Time Evolution of Thrombus Growth through Optical and Electrical Impedance data fusion

We designed a novel sensor specifically aimed at ex vivo measurements of white thrombus volume growth; a white thrombus is induced within an artificial micro-channel where hemostasis takes place starting from whole blood under flow conditions. The advantage of the proposed methodology is to identify the time evolution of the thrombus volume by means of an original data fusion methodology based on 2D optical and electrical impedance data simultaneously processed. On the contrary, the present state of the art optical imaging methodologies allow the thrombus volume estimation only at the end of the hemostatic process.

Impedance biosensor for real-time monitoring and prediction of thrombotic individual profile in flowing blood

A new biosensor for the real-time analysis of thrombus formation is reported. The fast and accurate monitoring of the individual thrombotic risk represents a challenge in cardiovascular diagnostics and in treatment of hemostatic diseases. Thrombus volume, as representative index of the related thrombotic status, is usually estimated with confocal microscope at the end of each in vitro experiment, without providing a useful behavioral information of the biological sample such as platelets adhesion and aggregation in flowing blood. Our device has been developed to work either independently or integrated with the microscopy system; thus, images of the fluorescently labeled platelets are acquired in real-time during the whole blood perfusion, while the global electrical impedance of the blood sample is simultaneously monitored between a pair of specifically designed gold microelectrodes. Fusing optical and electrical data with a novel technique, the dynamic of thrombus formation events in flowing blood can be reconstructed in real-time, allowing an accurate extrapolation of the three-dimensional shape and the spatial distribution of platelet thrombi forming and growing within artificial capillaries. This biosensor is accurate and it has been used to discriminate different hemostatic conditions and to identify weakening and detaching platelet aggregates. The results obtained appear compatible with those quantified with the traditional optical method. With advantages in terms of small size, user-friendliness and promptness of response, it is a promising device for the fast and automatic individual health monitoring at the Point of Care (POC).

Wearable instrument to measure simultaneously cardiac and electrodermal activities

The paper presents the design and characterization of a wearable instrument which measures simultaneously the electrodermal activity and the heart rate variability. The device measures the electrocardiogram on three channels and the skin potential response (endosomatic electrodermal activity) with a sample rate 1 kSa/s, 12 bits resolution. The bandwidth of ECG channels is [0.025, 160] Hz and the bandwidth of electrodermal channel is [0.08, 40] Hz. Data are transmitted via Bluetooth to a developed graphical user interface, which can run on a laptop or smartphone/tablet. The system is a useful tool to assess the sympathetic activity on heart rate variability.