Salvatore Castorina

Childhood IQ measurements in infants with transient congenital hypothyroidism

OBJECTIVE In view of the fact that, during the first period of life, thyroid hormones are critical for brain development, we investigated whether even transient congenital hypothyroidism could affect the long‐term intellectual development of affected infants.

Modeling and design of novel photo-thermo-mechanical microactuators

Abstract In this paper, an innovative actuation strategy based on a photo-thermo-mechanical energy transformation is introduced. The basic idea is to exploit a new way to get the required actuation energy from light in a highly efficient way by means of micro-machined lenses. The use of micro-lenses provides a way to improve the efficiency of the actuation system, compared with the direct exploitation of the heating produced by light. Furthermore, lenses helps in obtaining localized heating of the micro-actuator, preserving the remaining part of the system. This actuation system can be useful in those application fields where high actuation power is required and an electrical power supply is not accessible or not feasible, for example in autonomous microsystems where on-board power source is strongly limited. In fact, the proposed approach does not require electrical power supply to provide the actuation energy. In this work, the modeling and design of a device based on this novel actuation strategy are presented. A simple thermal microactuator consisting in a bilayer cantilever is taken here into account in order to focus the design on a concrete device. A standard Si technology, coupled with a compatible micromachining post-process, is moreover considered.

Development of autonomous, mobile micro-electro-mechanical devices

In this work a novel approach to realize an autonomous micro-robot is addressed. A full CMOS compatible silicon micro-machining process has been adopted to realize the mechanical parts of the system. An innovative photo-thermo-mechanical actuation strategy together with silicon micro-machining technology are used for the realization of thermal microactuators which act as legs. The basic idea is to provide the actuation energy needed for the motion of the system through a light source and to improve the thermo-electro-mechanical efficiency by using an array of micro-lenses that concentrate the energy of the light beam on a small region of the actuators. Novel smart optical structures, based on Photonic Band Gap (PBG) materials, realized by using several periods of suitable metal-dielectric couples must be selectively deposited over the micro-lenses in order to suitably address the motion of the legs.

Scaling issues and design of MEMS

Preface. Introduction. 1. Scaling of MEMS. 1.1 Introduction to Scaling Issues. 1.2 Examples of Dimensional Scaling Potentials. 1.2.1 Scaling effects on a cantilever beam. 1.2.2 Scaling of electrostatic actuators. 1.2.3 Scaling of thermal actuators. 1.3 Motivation, Fabrication and Scaling of MEMS. 1.4 Scaling as a Methodological Approach. References. 2. Scaling of Microactuators - an Overview. 2.1 Electrostatic Actuators. 2.1.1 Transverse combs modelling. 2.1.2 Lateral combs modelling. 2.2 Magnetic Transducers. 2.2.1 Magnetic actuators. 2.2.2 Ferromagnetic transducers. 2.3 Thermal Actuators. 2.3.1 Thermomechanical actuators. Acknowledgements. References. 3. Scaling of Thermal Sensors. 3.1 Thermoelectric Sensors. 3.2 Application: Dew-Point Relative Humidity Sensors. 3.2.1 Device structures and operating principles. 3.2.2 Device modelling and simulations. 3.2.3 Device design. 3.3 Conclusions. Acknowledgements. References. 4. Inductive Sensors for Magnetic Fields. 4.1 Inductive Microsensors for Magnetic Particles. 4.1.1 Integrated inductive sensors. 4.1.2 Planar differential transformer. 4.1.3 Signal-conditioning circuits. 4.1.4 Simulation of the planar differential transformer. 4.1.5 Experimental results. 4.2 Magnetic Immunoassay Systems. Acknowledgements. References. 5. Scaling of Mechanical Sensors. 5.1 Introduction. 5.2 Device Modelling and Fabrication Processes. 5.2.1 Fabrication processes. 5.2.2 Devices modelling. 5.2.3 Accelerometers. 5.2.4 Resonant mass sensors. 5.3 Experimental Device Prototypes. 5.3.1 CMOS devices. 5.3.2 SOI devices. 5.3.3 Finite element modelling. 5.4 Scaling Issues on Microaccelerometers and Mass Sensors. 5.5 Some Experimental Results. 5.6 Vibrating Microgyroscopes. 5.6.1 Coupled vibratory gyroscopes. Acknowledgements. References. 6. Scaling of Energy Sources. 6.1 Introduction. 6.2 Energy Supply Strategies for Autonomous Microsystems. 6.2.1 Use of microlenses in photothermomechanical actuation. 6.2.2 Technologies, materials and design of photothermomechanical actuators. 6.3 Photothermomechanical and Photothermoelectric Strategies for Highly Efficient Power Supply of Autonomous Microsystems. 6.3.1 Photothermoelectric power generation. 6.4 Efficiency of the Combined Energy Supply Strategy 166. References. 7. Technologies and Architectures for Autonomous MEMS Microrobots. 7.1 Design Issues in Microrobots. 7.2 A Microrobot Architecture Based on Photothermal Strategy. 7.3 A Microrobot as a Paradigm for the Analysis of Scaling in Microsystems. References. 8. Moving towards the Nanoscale. 8.1 Semiconductor-Based Nano-Electromechanical Systems. 8.2 Nanofabrication Facilities. 8.3 Overview of Nanosensors. 8.3.1 Use of AFM for materials and nanodevices characterization. 8.3.2 Scanning thermal microscopy (SThM). 8.3.3 Scanning Hall probe microscopy. 8.3.4 Mechanical resonant immunospecific biological detector. 8.3.5 Micromechanical sensor for differential detection of nanoscale motions. 8.3.6 Nanomagnetic sensors. 8.3.7 Nano-wire piezoresistors. 8.3.8 Nanometre-scale mechanical resonators. 8.3.9 Electric charge mechanical nanosensor. 8.4 Concluding Remarks. References. 9. Examples of Scaling Effects Analysis - DIEES-MEMSLAB. 9.1 Introduction. 9.2 Examples of Scaling Cantilever Beam Devices. 9.3 DIEES-MEMSLAB-Tutorial. 9.3.1 Introduction. 9.3.2 Descriptions of the microstructures and analytical methods. 9.4 Conclusions. References. 10. Concluding Remarks. Index.

Integrated inductive sensors for the detection of magnetic microparticles

In this paper, we deal with novel inductive microsensors, realized by using standard CMOS microelectronic technologies, for the detection of small amounts of magnetic beads that are placed in selected regions over the surface of the microsensor. The sensor proposed here represents a step toward the development of integrated inductive biosensors for application in the area of magnetic immunoassay where magnetic markers, carrying specific antibodies that selectively bind to the cells or molecules to be detected, are used; the measurement of the analyte concentration is therefore accomplished by determining the concentration of magnetic particles tied to it. A planar differential transformer structure is proposed here as part of the measurement strategy. The analysis, simulation, and design of the proposed device are reported, and its sensitivity to the quantity of micromagnetic beads deposited over its surface has been also demonstrated through experiments.

A CNN-based chip for robot locomotion control

In this paper a VLSI chip for real-time locomotion control in legged robots is introduced. The control is based on the biological paradigm of Central Pattern Generator (CPG) and is implemented by a Cellular Neural Network (CNN). The gait generation is accomplished by the CNN and is fully analog, while a digital controller modulates the behavior of the CNN-based CPG to allow the locomotion system to adapt to sensory feedback. The chip is designed with a switched-capacitor technique, fundamental to address the speed control issue. Experimental results on the first prototype are illustrated. These results confirm the suitability of the approach and open the way to the design of a fully autonomous bio-inspired micro-robot.

Technologies and architectures for autonomous "MEMS" microrobots

In this work, a novel approach to realize an autonomous micro-robot is addressed. Full CMOS compatible silicon micro-machining processes have been adopted to realize the mechanical parts of the system. An innovative photothermo-mechanical actuation strategy together with silicon micro-machining technology are used for the realization of thermal micro-actuators which act as legs. The basic idea is to provide the actuation energy needed for the motion of the system through a light source and to improve the thermo-electro-mechanical efficiency by using an array of micro-lenses that concentrate the energy of the light beam on a small region of the actuators. Novel smart optical structures, based on photonic band gap materials, realized by using several periods of suitable metal-dielectric couples must be selectively deposited over the micro-lenses in order to suitably address the motion of the legs.

A high sensitivity conditioning circuit for capacitive sensors including stray effects compensation and dummy sensors approach

A signal conditioning circuit for capacitive sensors, with high sensitivity and high linearity, is reported here. It is suitable for the measurement of small capacitive values and very small capacitance variations, and therefore it finds potential application in the capacitive characterization of novel material dielectric properties and in sensors exploiting such properties. In the proposed circuit, we make use of a particular configuration of current-to-voltage converter and of an impedance converter, which is adopted to compensate for the standing capacitance value of the sensor, and then to achieve high sensitivity to small capacitance variations. The presented topology is also suitable for the use in differential approaches where a dummy sensor is adopted to filter out unwanted interfering and modifying signals. The design, simulation and experimental characterization of the proposed circuit are reported here.

Dew-point relative humidity CMOS microsensors

In this work we present the development of relative humidity (RH) microsensors in standard CMOS technology and bulk micromachining. Miniaturization of RH sensors allows reducing size, response times, power consumption and costs. Our device makes use of dew-point temperature detection approach, to achieve simple operation and high reproducibility. It is based on a suspended plate, anchored to the substrate by means of four arms. The thermoelectric Peltier effect is exploited to cool the plate until an interdigitated capacitor on top of the plate detects moisture and triggers the temperature measurements by means of thermocouples. By measuring dew-point and ambient temperatures, RH can be calculated through psycrometric charts. We report here the modeling, simulation, design and experimental characterization of CMOS RH microsensors.

Integrated CMOS dew point sensors for relative humidity measurement

This work deals with the development of integrated relative humidity dew point sensors realized by adopting standard CMOS technology for applications in various fields. The proposed system is composed by a suspended plate that is cooled by exploiting integrated Peltier cells. The cold junctions of the cells have been spread over the plate surface to improve the homogeneity of the temperature distribution over its surface, where cooling will cause the water condensation. The temperature at which water drops occur, named dew point temperature, is a function of the air humidity. Measurement of such dew point temperature and the ambient temperature allows to know the relative humidity. The detection of water drops is achieved by adopting a capacitive sensing strategy realized by interdigited fixed combs, composed by the upper layer of the adopted process. Such a capacitive sensor, together with its conditioning circuit, drives a trigger that stops the cooling of the plate and enables the reading of the dew point temperature. Temperature measurements are achieved by means of suitably integrated thermocouples. The analytical model of the proposed system has been developed and has been used to design a prototype device and to estimate its performances. In such a prototype, the thermoelectric cooler is composed by 56 Peltier cells, made by metal 1/poly 1 junctions. The plate has a square shape with 200 μm side, and it is realized by exploiting the oxide layers. Starting from the ambient temperature a temperature variation of ΔT = 15 K can be reached in 10 ms thus allowing to measure a relative humidity greater than 40%.