34987 - Sensor and Actuators (2nd cycle)

Learning outcomes

At the end of the course the student will get basic knowledge to understand sensor systems and electronic interfaces. More specifically, the student will acquire a design methodology based on generic principle, instead of a collection of single topics or technology. The instruments will be focused on the demanding need to be prepared on the ever-changing new technology that the sensor micro- and nano-systems are providing for the Information and Communication Technologies and Bioengineering. Additionally, the student will have the knowledge to understand the most advanced application of sensors in the field of ambient monitoring and energetic consumption control.

Course contents

SENSORS and ACTUATORS SECTION (6 CFU)

The goal of this section is to provide to students the fundamental know-how regarding sensor and transducer systems design. The course scheme avoids to tackle the subject as a collection of different cases of sensing systems. Instead, it is structured to underline the common backgrounds of the sensing paradigms such as noise floor and sensing limits. More specifically, a generic sensor acquisition chain will be analyzed from the sensitivity and resolution point of view with respect to the background and devise noises. The learning outcomes are 1) understanding basic physical aspects of sensing and noise principles 2) analysis and design of electronic interfaces for sensors. Lectures are often based on a bottom-up approach to better understand principles from examples.

COURSE CONTENTS

    •    Introduzion of the course, example of research

    •    Sensors as a black-box. Concept of sensitivity, and relative sensitivity at first order approximation. 

    •    Measurements, precision, accuracy and resolution. Full scale and dynamic range.

    •    Recall of stocastic signals. Rms values and mean square values, standard deviations. Power spectral density. Correlation, autocorrelation and cross-correlation.

    •    Suprimposition of noise powers in uncorrelated signals. 

    •    The origin of noise. Brownian noise. The example of pressure sensor. 

    •    Noise in electronic components. Thermal noise and its derivation.

    •    Possonian processes. Shot noise and related derivation. 

    •    Concept of input-referred noise. Input referred noise in BJT and MOS devices. 

    •    The flicker noise and its derivation. Physical origin of flicker noise.

    •    Equivalent noise bandwidth. Signal-to-noise-ratio (SNR)

    •    White and pink noises.

    •    Acquisition sensor chain. Probability errors and equivalent number of levels.

    •    Noise in OPAMPs

    •    Resistive sensors interfaces. Wheatstone bridge and its sensitivity.

    •    Microcontroller sensing of resistors and capacitances. Ratioed measurements.

    •    Strain-gauges.  RTDs e PRTs.

    •    Thermistors, NTC e PTC. Magnetic sensors. 

    •    Capacitive sensors. Capacitance matrix. Kelvin guard ring.

    •    Charge amplifier. Differential capacitive sensing. Capacitive accelerometers.

    •    Noise in charge amplifiers. Correlated double sampling (CDS).

    •    Open and closed loop sensing. Oversampling converters. Sigma-Delta converters. Decimators.

    •    Lock-in e chopper sensing. Complex impedance measurements by lock-in sensing.

    •    Introduction to optical sensors. The photodiode. Charge and voltage photodiode readout in storage mode.

    •    Sensor networks.

    •    Array of optical sensors. Passive pixel CMOS sensors (PPS) and active pixel (APS) sensors. APS with correlated doble sampling. CCD principles. 

    •    Teoria del colore and color filtering.

NANOTECHNOLOGY SECTION (3 CFU)

This second part is aimed at giving the theoretical instruments to understand the main sensor transuction principles at microscale and nanoscale level. The contents will then be used in the context of protocols and instruments for biomedical and ICT laboratories.

• Photon-electron transduction. Photon interaction with matter. Quantum efficiency and spectral sensitivity.
• Ion-electron tranduction. Metal-liquid interface and interfacial states. Impedimetric characteristics of the interface.
• Electrical and magnetic polarization of the matter.
• Piezoelectricity and mechanical transduction.
• Nanosensors: nanopores, nanotubes, nanowires, graphene, bolometers.
• Instruments: optical and electron microscope; Atomic force microscope (AFM).

Readings/Bibliography

Physical principles: 

R. Feynman et al., The Feynman Lectures on Physics, Addison Wesley, 1963

Noise:

P. Gray, R. Meyer, Analysis and Design of Analog Integrated Circuits,  Wiley 1993

B. Razavi, Design of Analog CMOS Integrated Circuits, McGraw-Hill, 2000

Electrochemistry/Electrokinetics:

J. Bockris, A. Reddy, Modern Electrochemistry-2 Electrodics, Plenum, 1998

H. Morgan, N. Green, AC Electrokinetics: colloids and nanoparticles, RSP Press, 2001

Microfluidics & Microfabrication:

M. Madou, Fundamentals of Microfabrication, CRC Press, 2002

N.T. Nguyen, S. Wereley, Fundamentals and Application of Microfluidics, Artech, 2002

Sensors & signal conditioning:

R. Pallas-Areny, J. Webster Sensors and Signal Conditioning, Wiley, 2001

A/D - D/A conversion:

D. Johns, K. Martin, Analog Integrated Circuit Design, Wiley, 1997

Teaching methods

The slides of each lesson are available in AMS CAMPUS

Assessment methods

The exam consists of an oral interview of 40-60m on both teaching modules, which cannot be split at separate checkpoints. Particularly evaluated will be the critical skills of the student to be able to move within the program and to give a rational context to the statements made during the interview by the student. Expressive and specific language skills will be considered key factors for very positive evaluations. In the case of very positive reactions from the student, his ability to abstraction will be tested on some topics introduced in the course. Competition of formative gaps and inappropriate language will be negatively assessed and will lead to inadequacy.

Teaching tools

Frontal lessons

Office hours

See the website of Marco Tartagni