Pressure, Force, Motion, and Humidity Sensors

Pressure Sensors

In module 1 you will learn how to specify and use various types of pressure sensors for an embedded circuit. First, you will learn about piezoresistive, capacitive, and vacuum sensors. This includes a deep dive into the piezoresistive effect and how a Wheatstone bridge is used in these systems. This is followed by a discussion on pressure transmitters and how to calculate an error budget. Finally, we will give you examples of commercial pressure sensors and explain what you need to know to purchase them on a web site.

Force and Strain Sensors and Touch Screens

In module 2 you will learn how to specify and use various types of force and strain sensors for an embedded circuit. First, you will learn about how strain gauges use the piezoresistive effect and Wheatstone bridges to output a strain signal. Then you will learn how load cells use strain gauges to output a force signal. We have a video on a teardown of a weight scale for you to watch, where we teach you how the strain gauges are arranged in an unusual bridge circuit. Finally, we teach you about how touch screens used in kiosks, PC's and smart phones work. We have a lab exercise for you to perform on strain gauges, where you will get hands-on experience wiring the gauges into the PSoC system, and writing code to read the gauges.

Position, Acceleration and Velocity Sensors

In module 3 you will first learn how magnetic detection sensors such as Hall sensors and LVDT's work, as well as how capacitive detection sensors. Then you will learn how to specify and use accelerometers in an embedded circuit. We will discuss how the first accelerometers used the piezoelectric effect to output a sinusoidal signal. We will review the key principles and equations involved in vibrational measurement. Then you will learn later accelerometers used the piezoresistive effect and internal strain gauges to output a sinusoidal signal representative of force, as opposed to acceleration. Then we will explain how accelerometers are now using MEMS technology and changes in capacitive to output the signal. We teach you about gyroscopes, both traditional mechanical ones, still used in aircraft for angular position sensing, and modern MEMS ones used to determine angular velocity.

Motion, Distance and Humidity Sensors

In module 4 you will learn how to specify and use position and motion detectors in an embedded circuit. First, you will learn about the pyroelectric effect. Then you will learn how Passive Infrared motion detectors use the pyroelectric effect in commercial burglar alarms. Then you will learn how ultrasonic distance detection is accomplished, the same principles that whales, dolphins and bats use to navigate their worlds. We tackle microwave detection sensors last, as these are the most complex sensors that we cover in the course. They are used in long range position detection sensors and commercial security sensors for outdoors use.

Course Projects

This module contains the materials you need to complete the Strain Gauge lab assignment.