Industrial Consultancy & Sponsored Research (IC&SR) , IIT Madras
Technology Category/ Market
Category – Electronic Systems and Design manufacturing
Applications –Electronics, Automation, and
Automobiles, Mobile interface, Touchscreens ,displays
Industry – Sensors, Electrical and Semiconductors
Market -Sensors Market size was valued at USD 151.90 Billion in 2021 and is projected to reach USD 324.51 Billion by 2030, growing at a CAGR of 8.8% from 2023 to 2030
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Problem Statement
- Capacitive sensors often need complex signal conditioning to achieve output insensitivity
- For resistive sensors complexity associated with signal conditioning is relatively less compared to that for capacitive sensors, as they possess higher selectivity to the sensing parameters of interest
- However, in certain circuits resistance measurement itself could be sensitive to variations in coupling-capacitance
Technology
A device with a direct microcontroller interface unit, the device comprising:
Also, a method of directly interfacing a microcontroller (108) and a capacitively-coupled resistive sensor (102), the method comprising steps of:
- Decoupling a capacitively-coupled resistive sensor with a reference resistor and a reference capacitor
- Operating the microcontroller in a first measurement mode and a second measurement mode for predetermined time periods
- Determining a first time interval and a second time interval during discharging in the first measurement mode
- Determining a third time interval and a fourth time interval during discharging in the second measurement mode
- Determining resistance of the capacitively-coupled resistive sensor as a function of the first time interval, the third time interval, and the resistance of the reference resistor
- Determining effective coupling-capacitance of the capacitively-coupled resistive sensor
- The microcontroller operating in the first measurement mode configured to perform charging and discharging of the reference capacitor
- The effective resistance of the charging and discharging paths is equal to the resistance of the capacitively-coupled resistive sensor
- In some embodiments, the method includes disconnecting the capacitively coupled resistive sensor and the reference resistor in the first measurement mode.
- The first time interval is indicative of time taken for decrease in voltage across the reference capacitor to a first predetermined threshold voltage and the second time interval indicative of time taken for decrease in voltage across the reference capacitor to a second predetermined threshold voltage
- The third time interval is indicative of time taken for decrease in voltage of the reference capacitor to a first predetermined threshold voltage and the fourth time interval indicative of time taken for decrease in voltage across the reference capacitor to a second predetermined threshold voltage
Key Features/ Value Proposition
Technical Perspective:
- Simple direct microcontroller interface used to determine the value of coupling-capacitance independent of the value of the sensor and reference resistors, supply voltage and threshold voltage.
- The capacitively-coupled resistive sensor includes a resistor element coupled to a pair of capacitors in series connection.
- The output of the disclosed device is independent of the values of the coupling-capacitors, the reference capacitor, the DC excitation voltage, and the preset threshold voltage.
User Perspective:
- The device has a simple design and completes measurement in a few milliseconds.
- The device may be extensively used in non-intrusive sensing and monitoring applications based on capacitively-coupled resistive sensors
Questions about this Technology?
Contact For Licensing
sm-marketing@imail.iitm.ac.in
ipoffice2@iitm.ac.in
Research Lab
Prof. Bobby George
Department of Electrical Engineering
Intellectual Property
- IITM IDF Ref. 1985
- IN436429-Granted
Technology Readiness Level
TRL- 3
Experimental Proof of Concept