Force sensors are a much more integral part of our everyday lives than we give them credit for. These devices are used in everything from weighing scales to medical appliances to a wide range of industrial machinery.
The main role of a force sensor in most applications is to convert the mechanical force applied to an object into an electrical signal that gives you an accurate value of the magnitude of the force.
The ability of a force sensor to measure tension, compression, and other forces accurately makes them an indispensable tool in major industries like automation, robotics, IT, healthcare, and many more.
This blog covers force sensors in detail — highlighting their working principles, types, applications, and more. So keep reading till the end.
- What are Force Sensors?
- Working Principle of Force Sensors
- Types of Force sensors
- Load Cells
- Strain Gauges
- Force Sensing Resistors
- Ultrasonic Force Sensors
- Magnetic Force Sensors
- Capacitive Force Sensors
- Piezoelectric Force Sensors
- Applications of Force Sensors
What are Force Sensors?
Force sensors, in simple terms, are devices that can detect mechanical forces and convert them into corresponding electric output signals. Force sensors are designed to measure the force of tension, compression, expansion, etc., which are translated into electrical signals that are transmitted to indicators, controllers, or other processing devices.
Working Principle of Force Sensors
How do force sensors work? Well, the answer is quite simple. Force sensors operate by converting mechanical force into an electrical signal using techniques such as strain gauges, the piezoelectric effect, and capacitive sensing.
The basic principle involves the detection of applied force and its conversion into measurable quantities like changes in resistance, capacitance, or voltage.
Most force sensors use strain gauges which experience deformation under applied force. This deformation leads to a change in the electrical resistance of the material which is measured and converted into a force value.
Types of Force Sensors
Following are some common types of force sensors that are normally used in most applications.
- Load Cells
These are force transducers that can convert force generated from compression, weight, expansion, and other similar sources into an electrical signal.
Most load cells contain strain gauges which are thin foils that deform under force. The resistance of strain gauges varies with deformation and this change in resistance is converted into an electrical signal. Load cells are extensively used in smart weighing scales and other force or weight-measuring devices.
- Strain Gauges
Strain gauges consist of an insulating substrate with a zig-zag patterned metallic foil. The strain gauges compress and elongate in response to the applied force. The change in the length and cross-sectional area of the metallic foil changes its resistance which is measured with the help of a Wheatstone bridge circuit.
The change in resistance is converted into a voltage output which gives you a measure of the force.
- Force Sensing Resistors
Force sensing resistors or FRSs can measure changes in force by detecting variations in electrical resistance. These consist of a semi-conductive material placed between two flexible substrates with a spacer layer between them.
The application of force leads to the deformation of the conductive film. This changes resistance which varies inversely in response to the external applied force. The FRS sensors are used in:
- Electronic scales
- Robotics
- Medical devices
- Human-machine interfaces
- for overload detection in industrial systems
- Ultrasonic Force Sensors
These sensors use ultrasonic transducers that emit high-frequency sound waves. Under the applied force, there is a change in amplitude, frequency, and time that the sound takes to reach the receiver.
The changes in these quantities are measured and converted into the corresponding value of the applied force.
- Magnetic Force Sensors
These sensors use the principle of magnetostriction which states that under mechanical stress, the magnetic properties of a material experience a change. Under the force, the sensor’s ferromagnetic material experiences a shift in its magnetic permeability.
This change is detected via other magnetic sensors like coils which creates an electrical signal corresponding to the magnitude of the applied force. These sensors find uses in applications like biomechanics and microfluidics and environments with high electromagnetic interference.
- Capacitive Force Sensors
Capacitive force sensors use the principle of change in the capacitance of the capacitors under force. A capacitor has two conductive plates connected to a power supply.
The capacitance changes as the area of the plates or the separation between them alters by some external force. Under the action of force, the distance between the plates changes. This leads to a change in capacitance which can be measured and converted to the corresponding force value.
These force sensors are used extensively in proximity sensors, touch screens, and other low-force measurement applications.
- Piezoelectric Force Sensors
These sensors work on the piezoelectric effect principle. According to this principle, under applied mechanical stress or force, certain crystalline materials generate corresponding electric charges.
In these sensors, there are crystal elements with a carefully placed electrode between them. The application of force leads to deformation which changes the internal charge symmetry of the crystals. An electric charge proportional to the applied force is generated as a result.
A charge amplifier is used to convert the charge into a measurable digital signal which is then processed and displayed.
Applications of Force Sensors
Following are some common applications of force sensors across various industries:
- These are used in weighing scales like analytical balances, personal scales, and industrial weighing systems.
- They are also used in robotics, the pharmaceutical industry, and food processing.
- These are used in the manufacturing industry to ensure the systems are operating in safe ranges.
- These are also used in brake testing and seatbelt tension monitoring in the automotive industry.
- The healthcare field uses these in medical devices, rehabilitation equipment, and prosthetics.
- These are used in consumer electronics like smartphones, tablets, smartwatches, and other smart appliances.
Conclusion
A force sensor is a key tool in modern technology that ensures higher accuracy and efficiency in a wide range of industries like automotive, medical, robotics, and aerospace, to name just a few.
These are also an important component of almost every personal and commercial weighing scale.
Force sensors are available in a wide range of designs where each detects and then converts different types of forces into readable outputs. The choice of the force sensor in your case mainly depends on the type of force you need to measure, the capacity of the force, and accuracy requirements.
So, take these few points into account to find a force sensor that delivers the best results for your application.
You can visit us at Eagle Scales to explore our wide range of weighing solutions for all personal, healthcare, industrial, and commercial applications.
