Pencil drawn interdigitated capacitive sensors on wood substrate

• Published in: Advanced Sensor and Energy Materials Vol. 3; no. 4; p. 100103
• Main Authors: Thakur, Abhay Singh, Srivastava, Vinit, Vaish, Rahul
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 01.12.2024; Elsevier
• Subjects: Capacitor; Pencil; Sensors; Triple-mode sensor; Wood; Pencil; Sensors; Wood; Triple-mode sensor; Capacitor
• ISSN: 2773-045X; 2773-045X
• DOI: 10.1016/j.asems.2024.100103

This research presents the fabrication and characterization of an interdigitated capacitive (IDC) sensor on a wooden substrate using pencil traces. The resistance of the pencil traces decreased from 100 kΩ to 5 kΩ as the pencil grade shifted from HB to 8B. Concurrently, capacitance measurements revealed an increase from approximately 5 pF for a 5-finger IDC made with HB pencil to around 32 pF for an 8B pencil counterpart. Increasing the number of pencil traces from 10 to 50 resulted in a significant decrease in resistance and a proportional increase in capacitance. Application of the IDC sensor demonstrated notable changes in capacitance upon proximity and touch, with a significant decrease upon removal. The interdigitated capacitance sensor exhibits good proximity effects and contact sensitivity in touch, with capacitance increasing exponentially from 0.3 pF (7 cm) to 1.2 pF (direct contact), highlighting its ability to detect objects with high precision. Additionally, environmental factors such as temperature and humidity influence capacitance values. These findings underscore the potential of pencil-drawn IDC sensors for responsive and adaptable applications in various fields. •Functionalizing a wood substrate using graphite abrasion with pencil lead creating conductive pathways, making it a cost-effective and eco-friendly method for sensor development on biodegradable materials.•A triple-mode sensor capable of detecting proximity, touch, and pressure has been developed on a non-conductive fibrous material. This innovation showcases the versatility of wood as a substrate for multifunctional sensor applications, offering unique sensing capabilities in diverse environments.•The capacitance values range from 0.3 pF to 1.2 pF, providing flexibility for calibration adjustments within this range. This allows for precise tuning of the sensor's response and ensures accurate measurements across different conditions or use cases.•The sensor is connected to an Arduino Uno for real-life functionality, enabling real-time data processing and interaction with external systems. This integration enhances the sensor's versatility and applicability in practical applications.•The sensor's cost-effectiveness and eco-friendly fabrication and deployment highlight its strong potential in sustainable home solutions and green electronics.