Polyurethane-carbon Nanotubes@Bismuth Telluride Hybrid Aerogel: Preparation and Sensing Properties

doi:10.15541/jim20250286

Abstract

Abstract:

With the rapid development of intelligent equipment such as bionic humanoid robots, flexible tactile sensors have attracted increasing attention for their bionic haptic behaviors similar to human fingers. However, the existing sensing materials used for assembling multimodal flexible tactile sensors still lack the high-selective response capabilities, resulting in the cross-interference phenomenon of various output signals, which is difficult to meet the lightweight and integrated requirements of microsystems. In this study, a new-style polyurethane-carbon nanotubes@bismuth telluride (WPU-CNT@Bi₂Te₃) hybrid aerogel was designed and prepared, which exhibits a maximum compressive strain of 60% and a compressive strength of 9.4 kPa via the optimization of component ratios. Furthermore, according to the independent sensing principles of the piezoresistive effect of CNTs to mechanical pressure stimuli, and the thermoelectric effect of Bi₂Te₃ to changes in the external temperature, this hybrid aerogel derived flexible tactile sensor achieves high sensitivity (GF value of -1.28 kPa^-1, temperature response sensitivity of 1.2 K^-1, and minimum response temperature difference of 0.4 K) and rapid response behaviors (response and recovery times of 0.14 and 0.18 s for pressure, optimal response time of 0.28 s for temperature) to temperature and pressure, with high sensing stability (no degradation after 1300 thermal cycles) and non-mutual interference behaviors, endowing the equipped robotic hand with the perception capability to recognize both the hardness and temperature of various objects.

Key words: aerogel, flexible sensor, piezoresistive effect, thermoelectric effect

CLC Number:

TB332
O613

CAO Ying, PENG Lu, XIA Shuang, BAI Ju, ZHANG Ting, LI Tie. Polyurethane-carbon Nanotubes@Bismuth Telluride Hybrid Aerogel: Preparation and Sensing Properties[J]. Journal of Inorganic Materials, 2026, 41(5): 619-627.

Figures/Tables 12

Fig. 1 XRD patterns of WPU, Bi2Te3, CNT@Bi2Te3 and WPU-CNT@Bi2Te3

Fig. 2 Microscopic morphology, structure and elemental distribution of the WPU-CNT@Bi2Te3 aerogel (a, b) SEM images of the microscopic porous morphology of the aerogel; (c) TEM images of the crystal structure of CNT@Bi2Te3 in the hybrid; (d) Elemental distribution mappings of C, O, Te and Bi in the aerogel

Fig. 3 Static pressure response performance of the WPU-CNT@Bi2Te3 aerogel derived flexible tactile sensor (a) Resistance changing rates of the flexible tactile sensor under different pressures; (b) Corresponding response sensitivity of the flexible sensor; (c) I-V response curves of the flexible device under different pressures. Colorful figures are available on website

Fig. 4 Dynamic pressure response performance of the WPU-CNT@Bi2Te3 aerogel derived flexible tactile sensor (a) Response and recovery time; (b) Relationship between strain and resistance changing rate; (c) Resistance changing rates under the stepwise compression-recovery gradient test; (d) Influence of compression rate on the resistance variation. Colorful figures are available on website

Fig. 5 Schematic diagram and basic response performance of the WPU-CNT@Bi2Te3 aerogel derived flexible tactile sensor for temperature variations (a) Schematic diagram of the temperature-response output; (b) Thermoelectric output voltages under different temperature differences; (c) Seebeck coefficient fitting result; (d) Thermoelectric output voltages during the dynamic process of continuous heating and cooling

Fig. 6 Dynamic temperature discriminatory response and stability of the WPU-CNT@Bi2Te3 aerogel derived flexible tactile sensor (a) Dynamic discriminatory response behavior and (b) response time to positive and negative temperature differences; (c) Response results to the tiny temperature difference between the sensor and the fingers; (d) Response stability of the sensor under 1300 thermal cycles. Colorful figures are available on website

Fig. 7 Non-interference characteristics of the flexible sensor regarding to the pressure and temperature response behaviors (a) Influence of compression deformation on the temperature response behavior; (b) I-V curves under the same pressure (3 N) with different temperature differences; (c) Influence of temperature difference on the pressure response behavior. Colorful figures are available on website

Fig. 8 Practical performance of a robotic hand integrated with flexible sensor applied to recognize the properties of objects (a) Piezoresistive outputs for objects with different hardness and (b) corresponding linear relationship of hardnesses and outputs; (c) Thermoelectric voltages of water cups with different temperatures and (d) corresponding linear relationship of temperatures and outputs

Fig. S1 Preparation process flow chart of the WPU-CNT@Bi2Te3 aerogel

Fig. S2 Electrical resistivities and Seebeck coefficients of aerogels with different mass percentages of CNT@Bi2Te3

Fig. S3 Compression performance of WPU-CNT@Bi2Te3 aerogel (a) Optical image of practical recovering status under a strain of 50%; Stress-strain behaviors under (b) various compression strains of 10%-60% and (c) different compression speeds of 20-300 mm/min; (d) Cyclic test under a strain of 30%

Table S1 Comparison of performance between WPU-CNT@Bi2Te3 aerogel-based flexible tactile sensor and relevant studies

Sensitive material system	Sensor device structure	Multifunctional parameters	Sensing mechanism	Decoupling capability	Integration difficulty/Cost	Pressure sensitivity	Temperature sensitivity	Ref.
WPU-CNT@Bi₂Te₃	Aerogel monolith	Temperature, pressure	Thermoelectric piezoresistive	√	√ General	-19.9%/N (1.28 kPa^-1)	12.8 μV/K (1.2 K^-1)	This work
Ag nanoparticle/PDMS	Aerogel monolith	Temperature, pressure	Thermoelectric	×	× Relatively high	\	0.0017 K^-1	[15]
MWCNTs	Conventional membrane	Temperature, pressure	Thermoelectric piezoresistive	√	× General	0.74 kPa^-1	0.95 K^-1	[16]
PEDOT: PSS	Aerogel monolith	Temperature, pressure	Thermoelectric piezoresistive	√	× General	28.9 kPa^-1	<0.1 K^-1	[20]
PTFE	Conventional membrane	Pressure	Triboelectric	×	√ General	\	\	[24]
PEDOT:PSS/CNT	Conventional membrane	Static pressure, dynamic pressure	Triboelectric piezoresistive	×	× Relatively high	291699.6 kPa^-1	\	[25]
Liquid metal	Conventional membrane	Static pressure, dynamic pressure	Triboelectric	×	× Relatively high	\	\	[S1]
GO-PDMS/PTFE	Conventional monolith	Temperature, pressure	Triboelectric piezoresistive	√	× General	15.22 kPa^-1	1 K^-1	[S2]
Ag nanowires	Conventional membrane	Temperature, pressure	Thermal conductivity piezoresistive	×	× Relatively high	\	0.05 K^-1	[S3]
PDMS/liquid metal/NdFeB	Conventional monolith	Non-contact pressure	Magnetoelastic piezoresistive	√	× Relatively high	0.27 kPa^-1	\	[S4]
PDMS/ionic liquid	Conventional membrane	Non-contact pressure	Piezoresistive capacitance	√	× Relatively high	0.93 kPa^-1	\	[S5]

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