Yutong Shen,Shanshan Chai,Qingling Zhang,Mengdi Zhang,Xue Mao,Liang Wei,Fenglei Zhou,Runjun Sun,Chengkun Liu
The detection of lactate and other bioactive molecules is of great significance in biological research, medical testing, and environmental monitoring. Organic electrochemical transistors are a kind of biosensor devices, which can convert biological signals into electrical signals. In recent years, fiber-based organic electrochemical transistors (FECTs) provide a new approach for the construction of flexible wearable biosensors, promoting greatly the development of flexible wearable electronic products. In this study, a multilayer composite electrode was first prepared by incorporating MXene and PEDOT:PSS onto electrospun oriented polyvinyl formal (PVF) nanofiber bundle, and then assembled into FECT with high sensitivity and selectivity . Meanwhile, a wearable real-time monitoring platform was built to detect the lactate concentrations in human sweat. The results showed that MXene could act as a bridge between PEDOT:PSS and PVF, and the sensing performance of PVF/MXene/PEDOT:PSS-based FECT was enhanced obviously. It had a wide linear response range of 1 nM-100 mM, a sensitivity of 0.442 NCR/decade, a quick response time of 0.5 s, a low detection concentration, an excellent reproducibility, and a superior anti-interference characteristic. Therefore, this work provided more possibilities for the development of wearable biosensor.
Ionic-conductive polymers are appealing electrolyte materials for solid-state lithium-based batteries. However, these polymers are detrimentally affected by the electrochemically-inactive anion migration that limits the ionic conductivity and accelerates cell failure. To circumvent this issue, we propose the use of polyvinyl ferrocene (PVF) as positive electrode active material. The PVF acts as an anion-acceptor during redox processes, thus simultaneously setting anions and lithium ions as effective charge carriers. We report the testing of various Li||PVF lab-scale cells using polyethylene oxide (PEO) matrix and Li-containing salts with different anions. Interestingly, the cells using the PEO-lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) solid electrolyte deliver an initial capacity of 108 mAh g −1 at 100 μA cm −2 and 60 °C, and a discharge capacity retention of 70% (i.e., 70 mAh g −1 ) after 2800 cycles at 300 μA cm −2 and 60 °C. The Li|PEO-LiTFSI|PVF cells tested at 50 μA cm −2 and 30 °C can also deliver an initial discharge capacity of around 98 mAh g −1 with an electrolyte ionic conductivity in the order of 10 −5 S cm −1 .
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