This document discusses various types of force sensors, including digital and mechanical force gauges. It explains the functionality and history of piezoelectric sensors and strain gauge sensors, detailing their mechanisms for measuring force. Additionally, it covers the historical context and basic principles behind spring scale measurements.

1. Force Sensors
Done By Ahmad Taweel
1

2. Outline
• Introduction
• Digital force Gauge
• Piezoelectric sensor
• Strain Gauge sensor
• Mechanical force Gauge
• Scale spring
• References
2

3. Sensor
• A sensor is an object whose purpose is to detect
events or changes in its environment, and then
provide a corresponding output.
• Sensors typically use electrical or optical signals
as output
3

4. Force gauge
• A force gauge is a small measuring instrument
used to measure the force during a push or pull
test
• There are two kinds of force gauges today:
Mechanical and Digital force gauges
4

5. Digital force gauges
• Piezoelectric Sensor
• Strain gauge Sensor
5

6. Piezoelectric Sensor
• History
• Definition
• Mechanism
6

7. History
• Piezoelectric effect was first proven in 1880 by the
French Physicist brothers Pierre and Jacques Curie
• In the 1950s manufacturers begin to use the
piezoelectric effect
7

8. Definition
• The word “piezoelectricity” is derived from a Greek
word “pizo” or “piezein” which means to squeeze or
press
• A piezoelectric sensor: is a device that uses the
piezoelectric effect to measure changes in pressure,
acceleration, temperature, strain, or force by
converting them to an electrical charge
8

9. 9

10. Mechanism (1/2)
1. The charges in a
piezoelectric crystal are
exactly balanced
2. The effects of the
charges exactly cancel
out, leaving no net charge
on the crystal faces
10

11. Mechanism (2/2)
3. If crystal is
squeezed, the charges
are forced to be out of
balance
4. By squeezing the
crystal, a voltage is
produced across its
opposite faces—and
that's piezoelectric
effect
11

12. Strain Gauge Sensor
• History
• Definition
• Mechanism
12

13. History
• Invented by Edward E. Simmons and Arthur C.
Ruge in 1938
13

14. Definition
• A strain gauge is a device used to measure strain
on an object
• Strain can be related to stress, force
• As the foil is subjected to force, the resistance
of the foil changes in a defined way
14

15. 15

16. • Initial State:
• No compression
• No extension
• Resistance zero
16
Mechanism (1/3)

17. Mechanism (2/3)
• If a strip of conductive
metal is stretched, it will
result in an increase of
electrical resistance
17

18. Mechanism (3/3)
• If a strip of conductive
metal is broaden and
shorten, it will result in a
decrease of electrical
resistance
18

19. Mechanical force gauges
• Spring scale
19

20. History
• The first spring balance was made around 1770
by Richard Salter of Bilston.
• In 1838 they obtained the spring balance patent
20

21. Definition (1/2)
• A spring scale is a type of weighing
scale
• It consists of:
• Spring fixed at one end
• Hook to attach an object at the other
• The scale markings are equally spaced
21

22. Definition (2/2)
• Spring balances come in different sizes
• Small scales that measure newton will have a less firm
spring
• Larger ones that measure tens, hundreds or thousands
of newton or even more depending on the scale of newton
used (5000-8000)
22

23. Mechanism
• Measure only weight
• A spring scale will only read correctly in a frame
of reference
• It works by Hooke's Law
23

24. 24

25. References
• https://en.m.wikipedia.org/wiki/Force_gauge
• http://www.slideshare.net/researcher1234/ferroe
lectric-and-piezoelectric-materials
• https://en.wikipedia.org/wiki/Piezoelectric_sensor
• https://en.m.wikipedia.org/wiki/Strain_gauge
• https://en.m.wikipedia.org/wiki/Spring_scale
25

26. Thank You
26