Stretch Sensor: Development of Biodegradable Film

Abstract

This article presents research on biodegradable stretch sensors produced using biological material. This sensor uses a piezoresistive effect to indicate stretch, which can be used for force measurement. In this work, an attempt was made to develop the composition of a sensitive material and to design a sensor. The biodegradable base was made from a κ-carrageenan compound mixed with Fe₂O₃ microparticles and glycerol. The influence of the weight fraction and iron oxide microparticles on the tensile strength and Young's modulus was experimentally investigated. Tensile test specimens consisted of 10-25% iron oxide microparticles of various sizes. The results showed that increasing the mass fraction of the reinforcement improved the Young's modulus compared to the pure sample and decreased the elongation percentage. The GF of the developed films varies from 0.67 to 10.47 depending on composition. In this paper, it was shown that the incorporation of appropriate amounts of Fe₂O₃ microparticles into κ-carrageenan can achieve dramatic improvements in mechanical properties, resulting in elongation of up to 10%. The developed sensors were experimentally tested, and their sensitivity, stability, and range were determined. Finally, conclusions were drawn on the results obtained.

Keywords: biodegradable; force sensor; iron (III) oxide; stretch sensor; κ-carrageenan.

Figure 1

κ-Carrageenan molecule chemical structure.

Figure 2

Mechanical stand for strain sensor testing with samples: (a) view of the mechanical testbench, where A—force sensor, B—clamps, C—manual control panel; (b) sample fixing clamps; (c) schematic representation of experiment: a—clamps, b—electrodes, c—carrageenan film, d—multimeter.

Figure 3

Steps of sample preparation from carrageenan precipitates to film. (a) The precipitates of carrageenan. (b) Dried pure carrageenan film. (c) Precipitates of κ-carrageenan with iron (III) oxide. (d) Dried film of carrageenan with iron (III) oxide.

Figure 4

Investigation of the κ-carrageenan biopolymer film with Fe₂O₃ structures by SEM. (a) Micrograph of carrageenan biopolymer film cross-section with iron oxide Fe₂O₃ particles. Size = 1280 × 1100; DPI = 182.65; Conditions: V_acc = 15.0 kV; Mag- = ×60; WD = 12.40 mm. Pixel size = 231.771. (b) Micrograph of carrageenan biopolymer film with iron oxide Fe₂O₃ particles. Size = 1280 × 1100; DPI = 182.65; Conditions: V_acc = 15.0 kV; Mag- = ×30; WD = 10.60 mm. Pixel size = 4635.42. (c) Size = 1280 × 1100; DPI = 182.65; Conditions: V_acc = 15.0 kV; Mag- = ×1000; WD = 10.20 mm. Pixel size = 139.06; (d) Size = 1280 × 1100; DPI = 182.65; Conditions: V_acc = 15.0 kV; Mag- = ×1000; WD = 10.40 mm. Pixel size = 139.06.

Figure 5

View of films damaged by the applied force. (a) Broken carrageenan film, the composition with 0.5 mL of glycerol and 3 g of iron (III) oxide; (b) sample with 0.05 g of iron (III) oxide; (c) cracked specimen of carrageenan film, the composition with 3 mL of glycerol.

Figure 6

Investigation of samples with 30 mL Crgn + 0.5 mL Glc + 1 g Fe₂O₃. (a) Dependence of resistance under controlled force. (b) Dependence of resistance on the registered displacement of the sample during the mechanical load.

Figure 7

Investigation results of the sample containing the initial material proportions of 30 mL Crg + 0.5 mL Glc + 1 g Fe₂O₃ after 5 months of aging. (a) Dependence of resistance on the force applied to the sample. (b) The dependence of the measured resistance on displacement resulted from the applied load.

Figure 8

Investigation of sample with 0.5 mL glycerol and 0.05 g Fe₂O₃ in 3 g of carrageenan. (a) Dependence of resistance on the force applied to the sample with 30 mL Crg + 0.5 mL Glc + 0.05 g Fe₂O₃. (b) Dependence of resistance under displacement.

Figure 9

Investigation of the sample with 30 mL carrageenan + 0.5 mL glycerol + 0.05 g Fe₂O₃; sample aged 5 months. (a) Dependence of measured resistance on the applied load. (b) The dependence of measured resistance on displacement resulting from the applied load.

Figure 10

Investigation of a sample with 30 mL carrageenan + 3 mL glycerol+ 3 g Fe₂O₃. (a) Dependence of measured resistance on the applied load. (b) The dependence of measured resistance on displacement resulting from the applied load.

Figure 11

Visual representation of the displacement of samples; 1 and 1a: 30 mL Crg + 0.5 mL Glc + 1g Fe₂O₃ and 30 crg + 3 mL Glc + 3 g Fe₂O₃; 2 and 2a: 30 mL Crg + 0.5 mL Glc + 0.05 g Fe₂O₃; 3: 30 mL Crg + 3 mL glycerol + 3 g Fe₂O₃.