Facile Pressure-Sensitive Capacitive Touch Keypad for a Green Intelligent Human–Machine Interface

Muhammad Shumail Malik, Muhammad Hamza Zulfiqar, Muhammad Atif Khan, Muhammad Qasim Mehmood, Yehia Massoud*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

10 Scopus citations


There is a great demand for human–machine interfaces (HMIs) in emerging electronics applications. However, commercially available plastic-based HMIs are primarily rigid, application-specific, and hard to recycle and dispose of due to their non-biodegradability. This results in electronic and plastic waste, potentially damaging the environment by ending up in landfills and water resources. This work presents a green, capacitive pressure-sensitive (CPS), touch sensor-based keypad as a disposable, wireless, and intelligent HMI to mitigate these problems. The CPS touch keypads were fabricated through a facile green fabrication process by direct writing of graphite-on-paper, using readily available materials such as paper and pencils, etc. The interdigitated capacitive (IDC) touch sensors were optimized by analyzing the number of electrode fingers, dimensions, and spacing between the electrode fingers. The CPS touch keypad was customized to wirelessly control a robotic arm’s movements based on the touch input. A low-pressure touch allows slow-speed robotic arm movement for precision movements, and a high-pressure touch allows high-speed robotic arm movement to cover the large movements quickly. The green CPS touch keypad, as a disposable wireless HMI, has the potential to enforce a circular economy by mitigating electronic and plastic waste, which supports the vision of a sustainable and green world.

Original languageEnglish (US)
Article number8113
Issue number21
StatePublished - Nov 2022

Bibliographical note

Funding Information:
The authors would like to acknowledge the research funding to the KAUST Innovative Technologies Laboratories (ITL) from King Abdullah University of Science and Technology (KAUST).

Publisher Copyright:
© 2022 by the authors.


  • capacitive pressure sensors
  • graphite-on-paper
  • green
  • intelligent HMI
  • touch keypad

ASJC Scopus subject areas

  • Analytical Chemistry
  • Information Systems
  • Biochemistry
  • Atomic and Molecular Physics, and Optics
  • Instrumentation
  • Electrical and Electronic Engineering


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