Three-dimensional highway-like graphite flakes/carbon fiber hybrid electrode for electrochemical biosensor

Carbon-based electrodes are promising candidates for developing cheap, miniaturized, and disposable biosensors for effective, point-of-care disease management. However, their sensitivity is usually lower than gold electrodes due to polymer binders used during the procedure of ink formulating. Although surface pretreatment with reactive chemicals and addition of nanomaterials are available to enhance their sensor performance, both approaches may suffer from the use of hazardous substances and processing complexity. Here, we report an inexpensive, non-nanomaterials approach by making a graphite/carbon fiber (G/CF) hybrid electrode for biosensor applications. The hybrid electrode is formed by embedding a homemade graphite ink in the CF matrix of a commercially available carbon paper. This design resembles a super-efficient 3D highway network where ample expressways (CF) run through numerous small factories (locally distributed graphite flakes) for rapid goods pick-up and transportation (electron transfer). Featuring high conductivity, low impedance and large active surface area surpassing commercial screen-printed carbon electrodes, the G/CF hybrid electrodes show superior sensor performance for glucose detection as compared to counterparts prepared on electrodes without CF matrix. This study provides a new approach of enhancing electrochemical performance of carbon-based electrodes by structural design using macro-size scale, affordable materials.