EEET1413 / EEET 1464 - Sensors and measurement technologies

Individual assignment

Sensors and Measurement Technologies

Individual Assignment

Your supervisor hands you a datasheet of a temperature sensor from a medical system that is

currently undergoing technical improvement. You are informed that the sensor behaviour is

slow enough to be modelled with a first-order response. The datasheet of the temperature

sensor indicates that “ = (the last digit of your student number + the second last digit of your

student number + 5) seconds”. It also describes the calibration curve as “Linear, with an

output of 4 volts at 0

◦

C and (the third last digit of your student number + 5) volts at 35

◦

C”.

When testing the medical unit, it is initially kept at 5C for a long time before the test event

begins.

Question 1 – Derive a transfer function for this sensor and draw the calibration curve.

(10 marks)

Question 2 - Graph the sensor response when it is exposed to the testing temperature

profile shown in Figure 1 (Clearly outline your approach to graphing the sensor’s

output). (25 marks)

Figure 1. Temperature change applied to the sensor

The electronics system that the temperature sensor is connected to has a 16bit ADC with an

input range between 0.2V – 4.8V.

0 10 40 Seconds

C

30

25

20

15

EEET1413 / EEET 1464 - Sensors and measurement technologies

Individual assignment

Question 3 – Based on the calibration curve found in Question 1, design a signal

conditioning circuit that translates the output of the temperature sensor to the input

range of the electronics system’s ADC. Include simulation results. (20 marks)

Question 4 – What is the temperature sensor’s sensitivity? After digitization, what is the

digitized sensitivity of the temperature sensor? From the application perspective, is it

better or worse? (15 marks)

Question 5 – As part of the output of the electronics system, a warning light must be

active when the temperature is above 15 degrees. Add an electronic circuit that

facilitates this functionality. Include simulation results. (15 marks)

Question 6 – Upon the completion of Question 5, you accidentally find that the

temperature sensor is also sensitive to ambient mechanical vibration. When the

temperature is higher than 15 degrees, the response magnitude towards ambient

mechanical vibration equals to 1/10 of the temperature response magnitude. How do

you compensate the mechanical interference? Please include the relevant schematics

and possible simulation results. (15 marks)