Low-Profile, Large-Range Compressive Strain Sensing Using Micromanufactured CNT Micropillar Arrays

Abstract

Tactile sensors, or sensors that collect measurements through touch, have versatile applications in a wide range of fields including robotic gripping, intelligent manufacturing, and biomedical technology. Hoping to match the ability of human hands to sense physical changes in objects through touch, engineers have experimented with a variety of materials from soft polymers to hard ceramics, but so far, all have fallen short. A grand challenge for developers of “human-like” bionic tactile sensors is to be able to sense a wide range of strains while maintaining the low profile necessary for compact integration. Here, we developed a low-profile tactile sensor (∼300 μm in height) based on patterned, vertically aligned carbon nanotubes (PVACNT) that can repetitively sense compressive strains of up to 75%. Upon compression, reversible changes occur in the points of contact between CNTs, producing measurable changes in electrical admittance. By patterning VACNT pillars with different aspect ratios and pitch sizes, we engineered the range and resolution of strain sensing, suggesting that CNT-based tactile sensors can be integrated according to device specifications.

Wall Shear Stress Sensors Based on Carbon Nanotube Pillars

“…They show the potential for the design to be used as a microscale tactile sensor. The results further extend prior work, in which sensors consisting of ∼1 cm × 1 cm × 300 μm arrays of CNT pillars were shown capable of sensing normal loads of 5–100 mN by a piezoresistive mechanism …”

“…Carbon nanotube (CNT) pillars are promising materials for developing small drag-based flow sensors. The properties of CNTs have enabled chemical − and strain − sensor designs. CNTs have found use in flow sensors as well, ,− although these devices use CNTs for how the electrical properties of the material change due to stimuli.…”

Improving the Resolution of Flexible Large-Area Tactile Sensors through Machine-Learning Perception

“…Inspired by human skin, more and more researchers are working to prepare flexible tactile arrays with skin-like functionality to meet the needs of robotic mechanical claw grip state sensing − and have achieved perception capabilities far beyond skin. − Over the past decade, tactile array sensors have been extensively developed by utilizing different sensing mechanisms, such as resistive-, − capacitive-, − and piezoelectric-type mechanisms. − Among them, piezoresistive tactile sensors have become a focus of research due to their high load capacity, low mass production cost, low noise, and high tactile sensitivity. − Recently, advances in various functional materials, − structural designs, ,− fabrication methods, − and signal processing technologies − have further accelerated the development of tactile array sensors, which now enable pressure detection beyond the limits of the skin and ultrawide pressure monitoring ranges. However, some inherent characteristics of array-type tactile sensors limit their application in practical applications.…”