ELEC6263 Assignment 1: Packaging and characterisation of a piezoelectric accelerometer

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ELEC6263 Assignment 1: Packaging and characterisation of a piezoelectric accelerometer
Overview

The purpose of this assignment is for you to design, build and investigate the performance of a piezoelectric accelerometer that you have designed. You will use a small electromagnetic shaker table to test the device. The assignment will cover a variety of aspects including, research, design, simulation, construction, assembly and testing. You will be required to design a package for the accelerometer, based on 3D printing technology.

Objectives

You will need to understand the basic principles that are used on the design of state-of-the-art MEMS accelerometers. In particular, those based on piezoelectric materials. You will be given a small piezoelectric disc, which will be the main element of the accelerometer.
Tasks

1. Investigate and report on the principles of MEMS accelerometers.

2. Examine and report on the principles of operation of the piezoelectric disc. Make sure that you understand and explain the nature of the seismic mass and how it affects the frequency response of the disc. Find a relationship between the resonant frequency, the dimensions of the disc and its physical properties (such as modulus of elasticity) and the added mass. Calculate the approximate resonant frequency of the piezoelectric disc.

3. Measure and record the important electrical characteristics of the disc (capacitance etc.). Use an LCR bridge to measure these.

4. Design a suitable packaging for the accelerometer using SolidWorks, which is available on ECS computers. You will have a short briefing session on using this, but the best way is to learn it for yourself. SolidWorks will be used to generate the Stereo Lithography file (STL format), which is used to produce the 3D printed package. You will be assessed on the design of the package in terms of its functionality, compactness, engineering design and aesthetics.

5. 3D print your design and check that it has printed correctly and is fit for purpose. If necessary, revise and re-print your design. You should include at least one photograph of your printed package in your report and comment on any problems or notable features.

6. Explore and report on the signal conditioning circuits that are necessary to interface with the piezoelectric transducer.

7. Consider and report on how the transducers can be modelled by an electrical equivalent circuit. Discuss the effect of gravity on the accelerometers? What is the expected response 2 to vibration? How can you run a quick test to check the dynamic behavior of the piezoelectric disc in response to vibration, to assist with generation of your model?

8. Design and document an appropriate interfacing circuit for each of the transducers. If you decide to use a charge amplifier, it is recommended that you use a TL071/081 op-amp (these have an extremely high input impedance and are readily available in the drawers in the labs). Your circuits should operate from a ±15V supply and give an approximate ±5V output when the transducers are shaken at the maximum amplitude of the shaker (20V p/p between 0.5Hz-5kHz). Your design should only include components available from the drawers in the teaching lab.

9. Simulate and document the operation of your circuits in Multisim (or an alternative simulation package of your choice). Comment on whether your circuits meet your specifications, their linearity with respect to input frequency/amplitude, and how they behave across the range of conditions. If necessary, revise your design(s) to meet the specifications.

10. Build the circuits in the lab, on protoboard (you can get a protoboard issued to you by the lab technicians). You should test and document the basic functionality of your circuit and verify that it performs as simulated.

11. The electromagnetic shaker can be driven directly from a standard laboratory signal generator. A sine wave is an appropriate test signal. It is suggested that you limit the maximum amplitude of the sine wave to no more than 20V peak-to-peak. The output impedance of the signal generator is 50 Ω, but the impedance of the shaker is only 3 Ω, soyou will get a significant attenuation in the driving voltage to the shaker.

12. Attach the 3D printed structure to the shaker table via the threaded shaft. At this point, the piezoelectric accelerometer should have no mass added to the diaphragm. Choose THREE different amplitudes of the driving signal and sweep frequency from 0.5 Hz to 5 kHz. Observe and record the output of the piezoelectric device on an oscilloscope. You will need at least 10 readings for each frequency sweep, but you may find that some ‘interesting’ effects occur at specific frequencies that you want to investigate in more detail.

13. Glue a small nut to the centre of the diaphragm to act as a seismic mass. The weight of the nut is approximately 0.7 g. Repeat the tests in task 12 then glue another nut to increase the mass to 1.4 g and again repeat the frequency sweep tests. Examine the performance of the PZT accelerometer with and without the added mass.

14. A report is required for this assignment. You will need to describe the experiments that you have undertaken and to analyse the results that you have obtained. You will have a series of results from the piezoelectric accelerometer.

  • Were the results what you expected? How do you know that you obtained the correct response?
  • Can you explain and differences between the simulated and measured responses?
  • Did you observe any ‘unusual’ behaviour at certain frequencies and what might be the cause of this? 
Hints
  • In order to design the mount, you will need to know the dimensions of the piezoelectric disc, the size of the mounting rod for the shaker etc. Some of this information is available on the data sheets that you will be provided with, but you may also need to examine some components and take measurements yourself.
  • When testing the performance of the transducer, remember to consider the effect of the input impedance of the oscilloscope.
  • Remember to use your logbook to record your design process and experimental procedure.
Submission
A report is required for this assignment, which should fully describe each task. You will need to document your work and justify your design decisions. The report should follow the structure of a technical document and be a maximum of 10 pages, including references.

You may use additional pages for appendices.

You should use your logbook as a working record, to describe your design and practical work.

You will need to submit:

  1. An electronic (in PDF format) copy of the report.
  2. Scan (in PDF format) of relevant sections of your logbook to demonstrate how your initial ideas led to the final design of the package, circuits and testing methods.
  3. Design files (in ZIP format) associated with your design/simulations.

The mark scheme for this assignment can be found on the Handin website.

The deadline for this assignment is Tuesday March 17th, 2026 at 4pm.

This assignment forms 50% of the total assessment for this module and you can expect to spend 75 hours on this assignment.

Although you are encouraged to discuss this assignment with your colleagues, all work submitted must be your own. Reports and designs will be checked for plagiarism/collusion.

NM White and J Yan
January 2026

2026-03-17