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Makers and engineers: get to know your instrumentation amplifier for accurate IoT data capture

03 October 2018

Sensing is where the Internet of Things (IoT) and the smart home begins, and it’s where DIYers, makers, and even professional designers run into their first problem.

Many inexpensive transducers such as accelerometers, force sensors, strain gauges, and pressure transducers are designed around resistive Wheatstone bridges, so their outputs are differential voltages in the millivolt (mV) region. 

To ensure the data that is captured is accurate, designers need to become familiar with the instrumentation amplifier (INA). This is a balanced differential amplifier with easily controllable gain, low offset drift, and noise-cancelling properties.

Piezo-resistive transducers

One of the most popular families of transducers are those that use piezo-resistive elements. These are used to measure strain, force, acceleration, and pressure, to name a few applications. 

Small piezo-resistive elements are attached to the mechanical elements of the transducer. The desired parameter sensed causes the mechanical structure to deform. The piezo-resistive elements undergo strain proportional to the sensed parameter which changes the elements’ electrical resistance. 

Read the full article in the October issue of DPA

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