Goal of the course is to provide a basic knowledge of the most significant use of sensors, circuits, electronics systems in the biomedical instrumentation, starting from recalling the basic principles of the instrument/technique and then analysing and designing the components and electronics circuits (analog and digital) employed in the instrument. The tipologies of instruments considered in the course are: conventional and advanced instrumentation for the analysis of signals of biological origin, systems for medical imaging based on the use of radiation (X and gamma rays). Special focus of the course will regard application of microelectronic technology and circuits to the considered topics.

Knowledge and understanding

After passing the exam, the student:

• knows the fundamental principles, generalizations, theories and concepts of devices, circuits and electronic systems used in biomedical instrumentation
• knows the terms and basic principles of electronics used in biomedical instrumentation
• includes the operation of a circuit or electronic system used in biomedical instrumentation
• includes the characteristics / needs / constraints of devices, circuits and electronic systems used in biomedical instrumentation

Applying knowledge and understanding

After passing the exam, the student:

• is able to apply his knowledge to specific problems in the electronics applied to biomedical instrumentation
• is able to select the principles and concept useful for obtaining solutions to problems of devices, circuits and electronic systems used in biomedical instrumentation
• designs electronics circuits or systems for processing signals of biological origin or for medical imaging
• measures the performance of an electronic system used in biomedical instrumentation
• defines the specifications of an electronic system used in biomedical instrumentation
• implements a complete electronics system project used in biomedical instrumentation

I part – Electronics for the processing of biological signals

1) Origin of the biological signals. Electrodes and sensors employed for the signal acquisition.

2) Analog circuits for the amplification and filtering of biological potentials. Application in the electrocardiograph. Amplifier for bio-potentials: basic parameters and design issues (noise, insulation and protection techniques, common-mode and interferences rejection). Application of the Instrumentation amplifier to the measurement of bio-signals.

3) The electronics of the pacemaker: basic functionalities, batteries, amplification circuits, pulses generators, telemetry. Integrated circuits used in the pacemaker, example of time-invariant architectures and switched-capacitor topologies. Integrated charge pumps for the increase of the power supply. Examples of amplifiers and filters. Low-power and low-voltage designs based on the use of transistors operating in sub-threshold regime.

4) Special topic on application of integrated technologies in the biomedical field: microelectronics systems for artificial vision.

II part – Electronics for medical imaging systems

1) Basics on diagnostic medical systems based on the use of radiation. Digital radiography, computed tomography, SPECT and PET. Figures of merit: efficiency, resolution, signal/noise ratio. Examples of application in the medical field. The PET time-of-flight.

2) The Anger Camera. Architecture and components. Scintillators coupled to photodetectors (photomultiplier tubes, PiN photodiodes, avalanche photodiodes). Basic on collimation systems for the radiation (parallel holes, pinholes). Estimation methods for the determination of the ionizing event in the detector (centroid, maximum likelihood, neural networks). Effect of the electronics noise of the photodetector-amplifier in the spatial and energy resolution.

3) Integrated circuits employed in the medical imaging systems. Examples of design of the integrated front-end. Recall of the electronics noise and its representation by means of the equivalent noise charge. The charge preamplifier and the optimization of the input transistor. The integrated filter. The peak stretcher (Kruiskamp and Leenaerts type). The baseline holder.  Examples of design of integrated circuits by means of Cadence (optional laboratory drills).

4) Basic timing techniques: leading edge, constant fraction discriminator, zero-crossing discriminator. Application in PET.

Knowledge of fundamentals on electronics devices and circuits. For non-electronics students, e.g. biomedical students, special lessons will be provided at the beginning of the course to provide complements of electronics topics.

The examination is based on a oral exam only.