In order to improve the quality of Hunyuan inferior Ca-based bentonite （Ca-Bent）, semidry process was used to modify Ca-Bent into superior Na-based bentonite （Na-Bent）. The factors affecting sodium-modification we...In order to improve the quality of Hunyuan inferior Ca-based bentonite （Ca-Bent）, semidry process was used to modify Ca-Bent into superior Na-based bentonite （Na-Bent）. The factors affecting sodium-modification were investigated. The optimized experimental parameters are obtained as follows： Na2CO3 dosage 4.0%, ageing time 25 d, briquetting pressure 25 MPa and briquetting moisture 20%. Under the optimization conditions, the modified Na-Bent has a colloid value of 73.6 mL/（3g）, dilation of 38 mL/g and water absorption in 2 h （2HWA） of 465%, respectively. The bailing results indicate that the modified Na-Bent pellets have higher drop strength and compression strength than the Ca-Bent pellets.展开更多
Herein,we fabricated a flexible semidry electrode with excellent mechanical performance,satisfactory self-adhesiveness,and low-contact impedance using physical/chemical crosslinked polyvinyl alcohol/polyacrylamide dua...Herein,we fabricated a flexible semidry electrode with excellent mechanical performance,satisfactory self-adhesiveness,and low-contact impedance using physical/chemical crosslinked polyvinyl alcohol/polyacrylamide dual-network hydrogels(PVA/PAM DNHs)as an efficient saline reservoir.The resultant PVA/PAM DNHs showed admirable adhesive and compliance to the hairy scalp,facilitating the establishment of a robust electrode/skin interface for biopotential signal transmission.Moreover,the PVA/PAM DNHs steadily released trace saline onto the scalp to achieve the minimized potential drift(1.47±0.39 mV/min)and low electrode–scalp impedance(18.2±8.9 kΩ@10 Hz).More importantly,the application feasibility of real-world brain−computer interfaces(BCIs)was preliminarily validated by 10 participants using two classic BCI paradigms.The mean temporal cross-correlation coefficients between the semidry and wet electrodes in the eyes open/closed and the N200 speller paradigms are 0.919±0.054 and 0.912±0.050,respectively.Both electrodes demonstrate anticipated neuroelectrophysiological responses with similar patterns.This semidry electrode could also effectively capture robust P-QRS-T peaks during electrocardiogram recording.Considering their outstanding advantages of fast setup,user-friendliness,and robust signals,the proposed PVA/PAM DNH-based electrode is a promising alternative to wet electrodes in biopotential signal acquisition.展开更多
基金Project(50725416) supported by the National Science Fund for Distinguished Young Scholars Project(50804059) supported by the National Natural Science Foundation of China+1 种基金 Project(2008BAB32B06) supported by the Key Project in the National Science and Technology Pillar Program during the 11th Five-Year Plan PeriodProject(200805331080) supported by the Specialized Research Fund for the Doctoral Program of Higher Education
文摘In order to improve the quality of Hunyuan inferior Ca-based bentonite （Ca-Bent）, semidry process was used to modify Ca-Bent into superior Na-based bentonite （Na-Bent）. The factors affecting sodium-modification were investigated. The optimized experimental parameters are obtained as follows： Na2CO3 dosage 4.0%, ageing time 25 d, briquetting pressure 25 MPa and briquetting moisture 20%. Under the optimization conditions, the modified Na-Bent has a colloid value of 73.6 mL/（3g）, dilation of 38 mL/g and water absorption in 2 h （2HWA） of 465%, respectively. The bailing results indicate that the modified Na-Bent pellets have higher drop strength and compression strength than the Ca-Bent pellets.
基金supported by the National Natural Science Foundation of China (Nos.62176089,61703152)the Hunan Provincial Natural Science Foundation (Nos.2021JJ30226,2018JJ3134)+1 种基金Scientific Research Foundation of Hunan Provincial Education Department (No.21B0532)Science and Technology Planning Project of Zhuzhou (No.2020015).
文摘Herein,we fabricated a flexible semidry electrode with excellent mechanical performance,satisfactory self-adhesiveness,and low-contact impedance using physical/chemical crosslinked polyvinyl alcohol/polyacrylamide dual-network hydrogels(PVA/PAM DNHs)as an efficient saline reservoir.The resultant PVA/PAM DNHs showed admirable adhesive and compliance to the hairy scalp,facilitating the establishment of a robust electrode/skin interface for biopotential signal transmission.Moreover,the PVA/PAM DNHs steadily released trace saline onto the scalp to achieve the minimized potential drift(1.47±0.39 mV/min)and low electrode–scalp impedance(18.2±8.9 kΩ@10 Hz).More importantly,the application feasibility of real-world brain−computer interfaces(BCIs)was preliminarily validated by 10 participants using two classic BCI paradigms.The mean temporal cross-correlation coefficients between the semidry and wet electrodes in the eyes open/closed and the N200 speller paradigms are 0.919±0.054 and 0.912±0.050,respectively.Both electrodes demonstrate anticipated neuroelectrophysiological responses with similar patterns.This semidry electrode could also effectively capture robust P-QRS-T peaks during electrocardiogram recording.Considering their outstanding advantages of fast setup,user-friendliness,and robust signals,the proposed PVA/PAM DNH-based electrode is a promising alternative to wet electrodes in biopotential signal acquisition.
