Advances in Fiber-Based Wearable Sensors for Personal Digital Health Monitoring

Abstract

With the continuous growth of the global economy, an increasing concern has emerged among individuals with regard to personal digital health. Smart fiber-based sensors meet people's demands for wearable devices with the advantages of excellent skin-friendliness and breathability, enabling efficient and prompt monitoring of personal digital health signals in daily life. Furthermore, by integrating machine learning and big data analysis techniques, a closed-loop system can be established for personal digital health, covering data collection, data analysis, as well as medical diagnosis and treatment. Herein, we provide a review of the recent research progress on fiber-based wearable sensors for personal digital health. Firstly, a brief introduction is provided to demonstrate the importance of fiber-based wearable sensors in personal digital health. Then, the monitoring of biophysical signals through fiber-based sensors is described, and they are classified based on different sensing principles in biophysical signal monitoring (resistive, capacitive, piezoelectric, triboelectric, magnetoelastic, and thermoelectric). After that, the fiber-based biochemical signal sensors are described through the classification of monitoring targets (biofluids and respiratory gases). Finally, a summary is presented on the application prospects and the prevailing challenges of fiber-based sensors, aiming to implement their future role in constructing personal digital health networks.

Keywords: biochemical signal; biophysical signal; fiber-based sensor; personal digital health; wearable sensors.

Figure 3

(a) Schematic diagram of the developed wireless signal processing module and real-time display interface for smartphones [48]. Copyright © 2023 Elsevier. (b) Detection of the signals generated by the strain sensor under extreme conditions. (b) Schematic of SiO₂ and PDMS-modified treated fibers. (c) Demonstrate the ability of strain sensors to monitor underwater and extreme cold conditions. The insets are the photographs of the sensor in operation [49]. Copyright © 2022 Springer Nature. (d) Schematic diagram of the fiber-based pressure transducer used to monitor the amount of pressure applied to a varicose vein treatment band. (e) A photo of the smart glove and a schematic of the transfer to the smart device app via Bluetooth technology [13]. Copyright © 2023 Elsevier. (f) Schematic structure of a wearable pressure sensor prepared through 3D textile-assisted carbonized cellulose fabric (3DTACCF) [52]. Copyright © 2022 Elsevier.

Figure 4

(a) A water-washable capacitive pressure sensor was prepared based on hydrophobic nanofiber membranes [54]. Copyright © 2019 American Chemical Society. (b) The electrical output curve of the sensor applied to human pulse monitoring [55]. Copyright © 2021 American Chemical Society (c) The schematic diagram of capacitive pressure sensors based on micropatterned dielectric layers. (d) Demonstration of the fast response/recovery time of micropatterned capacitive pressure sensors [56]. Copyright © 2021 American Chemical Society. (e) The illustration of a piezoelectric nanofiber sensor inspired by muscle fibers [60]. Copyright © 2021 Wiley–VCH. (f) Photos of the textile triboelectric nanogenerators with sewn, woven, and knitted structures. (g) Effect of different fabric structures on transition point pressure, sensitivity, and linearity of the sensor [61]. Copyright © 2020 Elsevier.

Figure 6

(a) Optical photo of fiber cross-section before and after the thermal drawing process, with PLA and rGO forming a sensing layer. (b) Photograph and sensing curves of a temperature sensing glove [27]. Copyright © 2023 Springer Nature. (c) A sensor array capable of simultaneously detecting temperature and pressure stimuli can be transmitted to smart devices via Bluetooth [78]. Copyright © 2023 Wiley-VCH. (d) The voltage output curve of the PPSF sensor, demonstrates its high resolution and fast response. (e) Photograph of a vest made directly from the PPSF material [11]. Copyright © 2020 American Chemical Society.

Figure 8

(a) Schematic of the MECS integrated with cotton diapers [100]. Copyright © 2022 American Chemical Society. (b) A photo of an N95 mask integrated with TENG, which is used to power the internal ammonia sensor [107]. Copyright © 2023 Elsevier. (c) Photograph of wearing the acetone sensor while exercising. (d) Working mechanism of the acetone sensor. (e) Acetone sensor masks for measuring the dynamic respiratory acetone level of volunteers under different dietary patterns. Blood β-hydroxybutyrate (BOHB) is used to assist in validating the data accuracy of acetone sensors [108]. Copyright © 2023 Elsevier. (f) A wearable fabric keyboard with humidity as the stimulus signal [109]. Copyright © 2021 Elsevier. (g) Time-voltage curves of the MEHS sensor for driving the LED illumination, with an illustration of the circuit schematic diagram [110]. Copyright © 2022 Elsevier.

Figure 1

A year-by-year breakdown of the relevant literature. The search criteria employed were the author keywords “fiber sensor”, “yarn sensor”, “textile sensor”, or “fabric sensor”, and the topic “health”. The data used in this analysis were sourced from the Web of Science Core Collection, November 2023.

Figure 2

(a) Fabrication of conductive treatment of Calotropis gigantea yarn (CGY). (b) Demonstrating that the GMF strain sensor is not sensitive to changes in temperature and humidity [45]. Copyright © 2023 Springer Nature. (c) The procedure for producing the multi-pathway conductive fabrics. (d) The confusion matrix for distinguishing different breathing patterns and the schematic diagram of the respiratory monitoring system [46]. Copyright © 2021 Elsevier. (e) Illustration of the CPF strain sensor prepared based on ALD. (f) Demonstration of the CPF strain sensors maintaining excellent durability under the effects of friction, washing, and light aging [47] Copyright © 2019 Springer Nature.

Figure 5

(a) The photo shows an active sensing bedsheet with a large area prepared through functional fibers and its actual application. Scale bar: 10 cm [17]. Copyright © 2020 Elsevier. (b) Demonstrating the ability of DMWES to keep skin dry and cool. (c) Demonstrating that the DMWES can discriminate pulse signals [68]. Copyright © 2023 Springer Nature. (d) Schematic of the 3D knitting process. (e) A smart insole prepared by a triboelectric nanogenerator for active sensing, illuminating warning lights, and sending danger signals [37]. Copyright © 2020 Springer Nature. (f) Schematic structure of the textile MEG. (g) Demonstration of the intrinsic waterproofness of the textile MEG. (h) Photograph of the textile MEG used for respiratory monitoring in the field as well as respiratory sensing curves [69]. Copyright © 2021 Elsevier. (i) The textile MEG can be used directly for underwater motion monitoring. Scale bar: 6 cm [14]. Copyright © 2021 Springer Nature.

Figure 7

(a) The illustration of multiple sensing yarns integrated into a fabric patch, and (b) photographs of flexible printed circuit boards and sensors attached to clothing [87]. Copyright © 2023 Wiley–VCH. (c) Photograph of the large-scale electrochemical fiber-based sweat sensor [18]. Copyright © 2023 Elsevier. (d) Increasing the sensing efficiency of the modified Janus fabrics to about 10 times that of the unmodified ones [88]. Copyright © 2023 Royal Society of Chemistry. (e) The fabrication process of the bi-electrode structure of the SYBSC [31]. Copyright © 2023 Elsevier. (f) The photos of the NFMAS in the flat and bent state, the wireless flexible circuit board, and worn on the wrist [89]. Copyright © 2023 Elsevier.