This study describes the design, simulation, and micro fabrication of a micro thermoelectric generator (μTEG) based on
planar technology using constantan (CuNi) and copper (Cu) thermocouples deposited electrochemically (ECD) on
silicon substrate. The present thin film technology can be manufactured into large area and also on flexible substrate with
low cost of production and can be used to exploit waste heat from equipments or hot surfaces in general. In the current
implementation, the silicon structure has been designed and optimized with analytical models and FE simulations in
order to exploit the different thermal conductivity of silicon and air gaps to produce the maximum temperature difference
on a planar surface. The results showed that a temperature difference of 10K across the structure creates a temperature
difference of 5.3K on the thermocouples, thus providing an efficiency of thermal distribution up to 55%, depending on
the heat convection at the surface. Efficiency of module has been experimentally tested under different working
condition, showing the dependence of module output on the external heat exchange (natural and forced convection).
Maximum generated potential at 6m/s airflow is 5.7V/m2 K and thermoelectric efficiency is 1.9μW K-2 m-2.
In this work, a compact low-cost system designed to detect low amounts of proteins in biological fluids is presented. The
system, based on time-gated fluorescence detection principle, is composed by a Single-Photon Avalanche Diode (SPAD)
pixel array, a LED excitation light source and a micro-machined reaction chamber coupled to a microfluidic network. A
dual-site binding strategy based on DNA aptamers is used for target protein recognition. The microreactor, composed of
an array of microwells covered with a transparent membrane, is functionalized with a primary aptamer, while a
fluorescent-tagged secondary aptamer is used for the detection. Preliminary measurements demonstrate the feasibility of
fluorescence lifetime detection to discriminate between different fluorophores. The detection of human thrombin protein
in 300nM concentration is reported as a biological proof of principle of the biosensor.
This work presents the development of tactile sensing arrays, inspired by cutaneous sensing in humans, for the fingertips
of a humanoid robot. The tactile sensing arrays have been developed in two phases. Microelectrode arrays (MEA),
having 32 sensing elements - each epoxy adhered with 25μm thick piezoelectric polymer (PVDF-TrFE) film, were
fabricated in the first phase. When connected to the gate of FET devices (external to the chip), each element on MEA
acts like an extended gate; thereby facilitating modulation of charge in the induced channel by the charge generated in
PVDF-TrFE film - as a result of applied force. Thus, each sensing element converts force into voltage. The tactile
sensing arrays developed in second phase work on the same principle but are free from any extended gate. These arrays
(having 25 sensing elements) use POSFET (Piezoelectric Oxide Semiconductor Field Effect Transistors) touch sensing
elements - in which, piezoelectric polymer film is directly spin coated on the gate area of the FET devices. Thus, a
POSFET touch sensing element 'senses and partially processes at same site' - as is done by receptors in human skin. The
spatial-temporal performance of these chips is similar to that of skin in the human fingertips.
Piezoelectric polymers have lossy and dispersive dielectric properties and exhibit higher viscoelastic losses. Due to their
lossy behavior, the lossy models developed for piezoceramics are insufficient for evaluating polymers. In this work we
present a novel SPICE implementation of piezoelectric polymers model which includes the mechanical,
electromechanical and dielectric losses. The mechanical/viscoelastic, dielectric/electrical and
piezoelectric/electromechanical losses have been included in the model by using complex elastic, dielectric and
piezoelectric constants - obtained from measured impedance of PVDF-TrFE sample. The simulated impedance and
phase plots of polymer, working in thickness mode, have been compared with measured data. The impedance and phase
plots have also been compared with those obtained by using the lossy model approaches reported earlier.
This work presents the design and simulations of an interdigitated micro-electrode array aimed to discriminate cancer cells, with potential applications in predictive oncology, diagnostics and anti-tumor drug research. The device has been designed and a technological fabrication process has been defined. The microsystem consists of a quartz substrate with gold electrodes and a microfabricated three-dimensional structure (glass/SU8) for cells confinement. The designed device consists of three separated part: two circular areas for confinement, detection and moving and a narrow channel between those areas for the transportation of the cells. The detection can be done by measuring the charge variations associated to the different membrane capacitances and conductivities of tumor and normal cells. Alternating electric field over the electrodes is used for moving the cells between the circular areas (Travelling Wave Dielectrophoresis TwDEP) as well as for levitating and trapping cells on the electrodes (positive-negative Dielectrophoresis p-nDEP). Analytical and Finite Elements simulations have been performed in order to verify the system reliability and to estimate the parameters in use, like operative frequency, voltage, expected velocity.
This work presents the realization of a MEMS-based miniaturized system for liquid chromatography focused on agrofood applications, and in particular on the detection of wine defects.
The main modules of the systems are: i.) a Si-based separation column with inlet/outlet for fluidic connections; ii.) a three-microelectrode voltammetric sensor. Moreover, a Platinum heater has been realized on the back side of the chip containing the Si column in order to operate at temperatures greater than the room temperature.
The realized device consists of a Silicon/Pyrex structure realised by anodic bonding. Microchannels and inlet/outlet have been fabricated by Deep Reactive Ion Etching (DRIE) and Tetra Methyl Ammonium Hydroxide (TMAH) wet etching respectively. The column has been functionalised with n-octyltriethoxysilane (C8-TEOS). A lift-off technique has been developed for realizing the Pt heater and the Pt microelectrodes on-chip.
In order to separately characterize the main modules of the device, a package of the system has been realized following a modular approach; appropriate tubing and nanovolume connections have been used in order to minimize dead volumes. Then other packages approaches have been considered in order to minimize dead volumes and to avoid leakage issues.
Preliminary characterization tests of the two main modules have been performed. The capability of the system to correctly retain and detect Acetic acid has been tested.
In this work, we describe the design implementation, validated by experimental results, of an innovative gas sensor array
for wine quality monitoring. The main innovation of this integrated array deals with the simultaneous outputs, from a
single chip on TO-12 socket, of 8 different signals coming from a WO3 thin film structure heated in a linear temperature
gradient mode, allowing an overall evaluation of gas sensing properties of the material in a 100°C-wide window,
typically from 300 to 400°C. The implemented sensitive layer is a WO3 film deposed by RF-sputtering. Preliminary tests
of gas sensing showed good responses to the target analytes for the specific application (1-heptanol, 3-methyl butanol,
benzaldehyde and ethyl-hexanoate).