基于纖維素的空氣凝膠因其互聯(lián)多孔網(wǎng)絡(luò)、低密度和優(yōu)異的壓縮性，特別適合用于柔性傳感器，這些特性使得有效的變形檢測(cè)和信號(hào)傳輸成為可能。然而，纖維素氣凝膠在應(yīng)變傳感應(yīng)用中的廣泛采用受到其有限壓縮性和抗疲勞性的限制。為解決這些問(wèn)題，研究通過(guò)協(xié)同方法開(kāi)發(fā)了復(fù)合氣凝膠傳感器，該方法將通過(guò)TEMPO氧化法制備的竹纖維素納米纖維（BCNFs）與甲基三甲氧基硅烷（MTMS）改性及氧化石墨烯（GO）摻雜相結(jié)合。

所得的BCNF/MTMS/還原石墨烯氧化物（rGO）氣凝膠通過(guò)凍干和碳化的一體化工藝制備。所制備的壓阻式傳感器具有彈性、導(dǎo)電的多孔結(jié)構(gòu)，具備卓越的傳感性能，展現(xiàn)出高壓縮敏感度（在20–30%應(yīng)變下，應(yīng)變系數(shù)可達(dá)2.45）。此外，該傳感器在監(jiān)測(cè)人體關(guān)節(jié)運(yùn)動(dòng)方面表現(xiàn)出優(yōu)異性能，展現(xiàn)出作為下一代健康監(jiān)測(cè)應(yīng)用中高性能柔性可穿戴應(yīng)變傳感器的潛力。本研究為開(kāi)發(fā)具有增強(qiáng)機(jī)械和傳感性能的先進(jìn)纖維素基氣凝膠傳感器提供了可行策略。

圖文導(dǎo)讀

圖1. Preparation process diagram of BCNF/MTMS/rGO aerogels.

圖2. SEM images of BCNF/MTMS/GO-0.5 (A, D), BCNF/MTMS/GO-1 (B, E), BCNF/MTMS/GO-1.5 (C, F), BCNF/MTMS/rGO-0.5 (G, J), BCNF/MTMS/rGO-1 (H, K), and BCNF/MTMS/rGO-1.5 (I, L) aerogels.

圖3. (A) TEM image of BCNF. (B) FTIR spectra and (C) XRD spectra of BF, PBF, BCNF, BCNF/MTMS/GO-1 aerogel, and BCNF/MTMS/rGO-1 aerogel. (D) XPS spectra of BCNF, BCNF/MTMS/GO-1 aerogel, and BCNF/MTMS/rGO-1 aerogel, along with (E) C 1s and (F) Si 2p spectra of BCNF/MTMS/rGO-1 aerogel. (G) Nitrogen adsorption–desorption isotherms and (H) pore sizes of BCNF, BCNF/MTMS/GO-1 aerogel, and BCNF/MTMS/rGO-1 aerogel.

圖4. (A) Loading and unloading processes of BCNF/MTMS/rGO-1 aerogel. (B) Retention of maximum stresses in BCNF/MTMS/GO-0.5, BCNF/MTMS/GO-1, and BCNF/MTMS/GO-1.5 aerogels at a strain of 50% for 50 cycles. (C) Stress–strain curves of BCNF/MTMS/rGO-1 aerogel at the maximum strains of 10, 30, and 50%, respectively. (D) Fatigue tests of several selected cycles on BCNF/MTMS/rGO-1 aerogel at 50% strain. (E) Retentions of maximum stress and total strain loss of BCNF/MTMS/rGO-1 aerogel during 100 cycles at 50% strain. (F) Comparison of water contact angles for BCNF, BCNF/MTMS/GO-1, and BCNF/MTMS/rGO-1 aerogels.

圖5. Electromechanical performance of BCNF/MTMS/rGO-1 aerogels. (A) Mechanism of electrical resistance variation. (B) Current–voltage characteristics under different strains (0, 10, 20, 30, 40, and 50%). Variation of resistance with different applied strains (C) and frequencies (D). (E) Strain-sensing performance of BCNF/MTMS/rGO-1 aerogel. (F) Cycling stability test under 30% strain for 800 cycles.

圖6. (A) Schematic representation of the pressure sensor’s structure. (B) Different bending angle signals of the finger. Resistance variation curves during the processes of (C) finger bending, (D) knee bending, and (E) elbow bending.

小結(jié)

本研究通過(guò)優(yōu)化溶液混合和凍干工藝，成功制備了BCNF/MTMS/rGO-1氣凝膠。竹纖維素納米纖維（BCNF）、甲基三甲氧基硅烷（MTMS）與還原石墨烯氧化物（rGO）的協(xié)同組合，制備出具有堅(jiān)固三維多孔結(jié)構(gòu)的氣凝膠，該結(jié)構(gòu)賦予其機(jī)械韌性，同時(shí)集成導(dǎo)電網(wǎng)絡(luò)可實(shí)現(xiàn)敏感應(yīng)變響應(yīng)（GF在20-30%應(yīng)變下可達(dá)2.45），并展現(xiàn)出卓越的循環(huán)穩(wěn)定性 （壓縮循環(huán)穩(wěn)定性可達(dá)800次循環(huán)）。基于氣凝膠的傳感器在監(jiān)測(cè)復(fù)雜人體運(yùn)動(dòng)方面表現(xiàn)出色，包括精細(xì)的手指運(yùn)動(dòng)和大范圍的關(guān)節(jié)彎曲。這些結(jié)果表明，BCNF/MTMS/rGO-1氣凝膠在毫米級(jí)運(yùn)動(dòng)（如手指、肘部和膝蓋彎曲）中展現(xiàn)出卓越的機(jī)械韌性和可靠的壓阻響應(yīng)，使其成為針對(duì)這些關(guān)節(jié)級(jí)變形可穿戴設(shè)備的理想候選材料。

文獻(xiàn)：

https://doi.org/10.1021/acsaelm.5c01129

審核編輯 黃宇