Strain gauge force sensitivity

• CharleyK
In summary, the individual is seeking advice on designing a force sensor for a project. They are considering using piezo-electric elements, strain gauges, or laser interferometers, but are concerned about finding the appropriate sensitivity and minimizing drift. They also mention the possibility of using voice coil assemblies from loudspeakers as a potential solution.

CharleyK

Hello, I'm new here and that's because I've run into a problem I can't reliable find anywhere else.
I guess I need some personal experience or input from someone.

I'm designing a force sensor for a project of mine, it will be measuring force in three orthogonal directions. Now, I'm confident I can design a platform with the required stiffness in all directions, but the problem is measuring.

I have several options, piezo-electric elements, strain gauges or laser interferometers.
I'm dealing with a force of a few tens of mN and I need a sensitivity of tens of μN. The force is also a very slowly changing force vector, so I guess piezo-electric won't be any good.

From what I gathered, piezo-resistive strain gauges have he highest sensitivity (save for capacitive methods), but most of the time the force sensitivity is a matter of signal amplification. I know a guy who could amplify a normal 2N load cell to a sensitivity of 0.1 mN, but does anyone know/think I can get strain gauges amplified with a 0.01 mN sensitivity without too much drift?

Or maybe know a site/source where I could find some guidelines for determining the force sensitivity of such a setup?

Thanks!
Charley

I believe you are operating below the sensitivity of most strain gauges.

I would consider using the voice coil assemblies from three loudspeakers. Remove the cone but not the suspension. By optically sensing the axial position of the voice coil you can maintain it's position with a DC current through the coil. Do that for each of the 3Ds and monitor the current needed to maintain position. Those currents are directly proportional to the force components.

What is a strain gauge force sensor?

A strain gauge force sensor is a device used to measure the amount of force applied to a particular object. It uses the principle of strain, which is the change in length or shape of an object when a force is applied, to measure the amount of force being exerted. The sensor typically consists of a thin metal strip or wire, called the strain gauge, attached to the object being measured. When the object is subjected to force, the strain gauge deforms and its electrical resistance changes, allowing for the measurement of force.

How does a strain gauge force sensor work?

A strain gauge force sensor works by converting mechanical energy (force) into electrical energy. When a force is applied to the object being measured, the strain gauge deforms and its electrical resistance changes. This change in resistance is then measured by an electrical circuit and converted into a corresponding electrical signal. This signal can then be calibrated to determine the amount of force being applied.

What are the benefits of using a strain gauge force sensor?

There are several benefits to using a strain gauge force sensor. One of the main benefits is its high accuracy and sensitivity. These sensors can measure even very small changes in force, making them ideal for precise measurements. They are also highly reliable and can withstand harsh environments, making them suitable for a variety of applications. Additionally, strain gauge force sensors are relatively easy to install and can be used to measure a wide range of forces, making them versatile and cost-effective.

What are some common applications of strain gauge force sensors?

Strain gauge force sensors have a wide range of applications in various industries. Some common applications include weighing scales, load cells, and force transducers used in industrial settings. They are also used in the automotive industry for measuring torque and strain, as well as in aerospace engineering for structural testing. Additionally, strain gauge force sensors are commonly used in medical devices, such as prosthetics and force-sensitive surgical instruments.

How can I choose the right strain gauge force sensor for my application?

When choosing a strain gauge force sensor, it is important to consider the range of forces that need to be measured, as well as the accuracy and sensitivity required. Other factors to consider include the environmental conditions the sensor will be exposed to, such as temperature and humidity, and the type of output signal needed (analog or digital). It is also important to select a sensor from a reputable manufacturer to ensure high quality and reliability. Consulting with an expert in the field can also help in selecting the right sensor for your specific application.