Question

Using credible sources, explain how the Wheatstone bridge circuit is applied in two biomedical devices. explain why this circuit was used in these devices!

Answer 1

A Wheatstone bridge is an electrical circuit used to measure an unknown electrical resistance by balancing two legs of a bridge circuit, one leg of which includes the unknown component. Its operation is similar  to the original potentiometer.

The  practical applications for the Wheatstone Bridge circuit is used for many biomedical applications to include but not limited to:

• MRI/CT - table positioning, accurate movement of the CT scan imaging device and equal patient weight distribution. High accuracy is needed to perform imaging functions while preventing over-travel of the patient placed within the scanning tube.A multi axis strain gauged sub-assembly is very effective in ensuring smooth reliable movement and table positioning while adjusting for weight distrbution.
• Infusion pumps/Syringe pumps - monitors and controls the amount of fluid flow of intravenous medication that was to be received via the tubing.
• Mammography - monitors the amount of physical force that is applied to the patients breast by the machine itself when attempting to take an image.
• Conventional radiography - monitors the amount of x-ray dose received to the AEC cells and the patient.
• Scales, weighing/Patient lifts - with the incorporation of a load cell into the bottom metal plates these scales routinely require re-zeroing which uses the above circuit.
• Remote robotic surgeries - used so physicians can precisely measure both depth of force and drill bit rotational force during remote hip surgeries etc.
• Strain guage in OEM Medical Devices and Equipment

Strain gauge technology:Very small and precise mechanical strain is measured using the Strain guage.Hence the strain guage must be included in a measurement system where accurate determination of a change in resistance us possible.It can be achieved by the Wheatstone bridge .

The Wheatstone bridge illustrates the concept of a difference measurement, which can be extremely accurate. Variations on the Wheatstone bridge can be used to measure capacitance, inductance, electrical impedance and other quantities, such as the amount of combustible gases in a sample, with an explosimeter.