Wearable strain sensors with a wide linear range (i.e., sensors established on piezoresistive materials) are highly desirable in detection of human motion, as well as for the evaluation of physical rehabilitation. However, most piezoresistive devices possess poor linearity in the working range due to the exponential collapse of the solid conductive structures under high strain, thus limiting their batch applications. Herein, a strain sensor with a broad linear detection range by virtue of a non‐Newtonian fluid (NNF) is reported. Graphitized carbon black (GCB) is employed to create the conductive network and subsequently embedded in defatted cellulose nanofiber (CNF)‐insulating framework. After the GCB/CNF liquid is encapsulated into the elastic polymer, the conductivity shows excellent response to tensile strain (gauge factor = 5.47). The conductivity does not drop sharply under large deformation, and the device reveals a linear response in the whole sensing range up to 100%. The sensor, which exhibits a stable performance with excellent sensitivity, durability, and low hysteresis, is applicable for real‐time monitoring bio‐signals, including pulse, muscle, and joint movements. All these results inspire a simple but promising route to design high‐performance wearable devices.
Objective
To explore the clinical effects of different forced expiratory volume in 1s (FEV
1
) reference equations on chronic obstructive pulmonary disease (COPD) airflow limitation (AFL) classification.
Methods
We conducted a COPD screening program for residents over 40 years old from 2019 to 2021. All residents received the COPD screening questionnaire (COPD-SQ) and spirometry. Postbronchodilator FEV
1
/FVC (forced vital capacity) <0.7 was used as the diagnostic criterion of COPD and two reference equations of FEV
1
predicted values were used for AFL severity classification: the European Respiratory Society Global Lung Function Initiative reference equation in 2012 (GLI-2012) and the Guangzhou Institute of Respiratory Health reference equation in 2017 (GIRH-2017). Clinical characteristics of patients in GOLD (Global Initiative for Chronic Obstructive Pulmonary Disease) 1–4 grades classified by the two reference equations were compared.
Results
Among 3524 participants, 659 subjects obtained a COPD-SQ score of 16 or more and 743 participants were found to have AFL. The COPD-SQ showed high sensitivity (59%) and specificity (91%) in primary COPD screening. Great differences in COPD severity classification were found when applying the two equations (p < 0.001). Compared with GIRH-2017, patients with AFL classified by GLI-2012 equations were significantly severer. The relationship between symptom scores, acute exacerbation (AE) history distributions and COPD severities classified by the two equations showed a consistent trend of positive but weak correlation. Group A, B, C and D existed in all GOLD 1 to 3 COPD patients, but in GOLD 4, only Groups B and D existed. However, no clear significant differences were found in symptoms, AE risk assessments, risk factors exposure and even the combined ABCD grouping under the two equations.
Conclusion
There were significant differences in COPD AFL severity classification with GLI-2012 and GIRH-2017 FEV
1
reference equations. But these severity estimation differences did not affect symptoms, AE risk assessments and ABCD grouping of patients at all GOLD grades.
Stretchable conductor (SCD) is one of the essential functional elements for soft electronics, such as next-generation wearable and bio-implantable device. However, most of the reported SCDs display a variable conductivity...
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