Capacitive angular displacement sensors: from materials and device architectures to wearable applications

Purpose This paper systematically reviews the past two decades of angular displacement sensor research, focusing on capacitive types. This paper aims to help readers grasp the classification, principles, performance and applications of angular displacement sensors, identify the technical challenges and the research gaps of capacitive sensors and provide references for sensor selection, optimization and innovation in scenarios like wearables and aerospace. Design/methodology/approach This paper first classifies angular displacement sensors into contact (e.g. potentiometer) and non-contact (e.g. capacitive, inductive and optical) types, outlining their core features. This paper then delves into capacitive sensors, explaining their flat capacitance principle, key issues (edge effect, parasitic capacitance and environmental sensitivity) and solutions (structural optimization and signal conditioning). This study reviews four typical capacitive sensor studies and compares performance parameters (resolution, precision, range and size) of various sensors via tables. Finally, this study summarizes applications in wearables, aerospace and engineering and discusses research gaps. Findings Capacitive angular displacement sensors stand out for their high precision/resolution, low power, simple structure and low cost, but face issues like edge effect and environmental sensitivity – mitigable via structural design, signal processing and environmental adaptation. They have achieved breakthroughs in miniaturization (less than 8 mm outer diameter), high precision (26-bit resolution) and multi-functionality (dual angular/linear measurement), with broad prospects in wearable monitoring and aerospace control. They balance performance and cost more effectively than inductive/optical sensors for industrial and wearable applications. Originality/value This paper uniquely focuses on in-depth analysis of capacitive sensors from principles to latest research. This paper constructs a performance comparison framework for angular displacement sensors, systematically summarizes wearable application details (e.g. hand/limb joint sensors) to fill existing gaps and identifies research gaps (precision, dynamic performance, fusion and miniaturization) and future directions (nanomaterials, three-dimensional printing and IoT integration) to guide innovative development.