# Research Progresses and Application of Biofuel Cells Based on Immobilized Enzymes
## 5 Conclusions and Outlook  
In conclusion, enzyme-based biofuel cells represent a promising technology for sustainable and eco-friendly power generation. The use of immobilized enzymes provides many advantages, including high stability, substrate specificity, and high efficiency, making EBFCs suitable for various applications. Despite significant progress in the development of EBFCs, several challenges still need to be addressed in order to fully realize their potential. One of the most pressing issues is the need for improved stability and lifetime of the enzymes used in EFBCs. Enzymes are typically susceptible to denaturation and deactivation under conditions such as high temperature, extreme pH, and exposure to organic solvents. Thus, finding strategiesto enhance the stability of enzymes under such conditions is crucial for the long-term operation of EBFCs. Another important issue is the need for improved efficiency and power output of EBFCs. Although enzymes have high catalytic activity, the power densities achieved by EBFCs are still relatively low compared to conventional fuel cells. Thus, developing new enzyme-based systems or optimizing existing ones to improve power output is a critical area of research. Finally, the integration of EBFCs into practical devices and systems requires the development of suitable electrode materials and designs, as well as the development of cost-effective and scalable production methods. Overall, addressing these urgent research issues is key to realizing the full potential of EBCs for a range of applications. In this review, although we have summarized the recent literatures' work using a variety of immobilization and modification strategies for enzymatic bioanodes and biocathodes, especially using those carbon-based nanomaterials which can be further improved by incorporating conductive polymers and other nanomaterials, there have been not many direct applications of these new strategies on the wearable and implantable devices based on EBFCs. There are still some technical gaps to be filled between the research of EBFCs and their applications in practice, and so far, there have been very few commercially EBFC available in the market, if any. While the low power output and limited enzyme lifespan are still major challenges, ongoing research in novel enzyme immobilization techniques, hybrid EBFC systems, and enzyme stabilization strategies offer great potential for improving the performance and lifespan of EBFCs. Although there are many types of natural enzymes, almost all of them more or less have a stability issue and require mild reaction conditions and the cost of biological enzymes is not low, which limits the expanded application of EBFCs and makes it difficult to commercialize them. So, it is also important to reduce the cost of manufacturing EBFCs and apply them to complex environments. It is expected to develop suitable and efficient artificial or mimetic enzymes to replace natural enzymes for catalytic reactions. The future of EBFC technology looks promising, particularly in the fields of implantable and wearable devices. In the coming years, we expect to see further progress in enzyme engineering and immobilization techniques, as well as the integration of EBFCs with other devices and systems. With ongoing advancements in enzyme engineering, enzyme immobilization strategies, and hybrid energy conversion systems, the power output and efficiency of EBFCs are expected to continue to improve. Moreover, the use of sustainable and eco-friendly biofluids as fuel sources makes EBFCs an attractive option for sustainable energy production. In the future, we can expect to see more practical applications of EBFCs, particularly in the medical and wearable device industries. With the increasing demand for sustainable and renewable energy sources, the potential for EBFCs to revolutionize the energy industry is enormous. Conceptualization, C.L. ([PERSON]), J.Z. and N.T. ; methodology, J.Z. and C.L. ([PERSON]); validation, J.Z. and H.Y. ; formal analysis, J.Z. and C.L.