High-Performing Electrochemical Sensors enabled by Electropsun Laser-Induced Carbon Nanofibers

Since its emergence, laser-induced carbon nanomaterial technology has revolutionized the fabrication of flexible electrodes applicable in several areas, which includes the development of high-performing electrochemical sensors at low cost. A wide array of substrates and composites have been successfully converted into carbon nanomaterials as well as their associated functional hybrids. Electrospun nanofibers as a substrate have caught our attention owing to their 3D-fibrous structure featuring high porosity and huge surface area-to-volume ratio, foreseeing the enhanced detection sensitivity when they are employed as electrochemical transducers. Moreover, doping the polymer solution prior to spinning allows tuning of properties and convenient modifications of fiber precursor, enabling facile fabrication of electrochemical transducers with favorable functionalities. In addition, their manufacturing process can be effectively controlled via spinning parameters, and easily scaled up at relatively low cost. However, when electrospun nanofibers are subjected to laser-processing their fluffiness and delicate structure pose significant challenges, which required thorough investigations to enable laser-induced carbon nanofibers (LCNFs) with desired properties. This talk will first highlight the parameters of the electrospinning and lasing processes, which critically govern the morphological and electroanalytical properties of the LCNF electrode. Afterwards, the talk will focus on how to implement the strategy to realize high performing enzyme-less electrochemical sensors. Here, the incorporation of metal salt precursor into the electrospun nanofibers allows for further <i>in situ</i> formation of electronanocatalysts embedded with the LCNFs. Through electrospinning, the metal precursor can be uniformly distributed within the nanofibers, subsequently promoting homogeneous dispersion of the nanocatalysts within the LCNFs. As shown in an exemplary case, the immense electroactive surface area of LCNFs with highly dispersed Ni nanoparticles permitted the detection of glucose in sub μM range, which considerably outstands other reports where sophisticated procedure and costly instruments were required. Furthermore, the strategy for integration of LCNFs into miniaturized devices will be illustrated. Herein, the devices contained 3D-porous electrochemical transducers with pore sizes of ca. 5-10 μm (an order of magnitude smaller than the pores in comparable graphene foam) and unsurprisingly offered an impressive limit of detection for dopamine sensing (down to pM range). Finally, the talk will demonstrate LCNFs as part of a lateral flow assay (LFA). Here, 25-fold enhancement in detection sensitivity of a common redox marker could be obtained when compared to the LFA integrated with a flat screen-printed electrode. Overall, the investigations have proven that LCNFs are highly promising for the development of point-of-care testing where high analytical performance can be achieved together with high affordability.