Metal ions are known to play various roles in living organisms; therefore, the detection of metal ions in water resources is essential for monitoring health and environmental conditions. In contrast to artificially fabricated materials and devices, biological-friendly materials such as microalgae have been explored for detecting toxic chemicals by employing fluorescence emissions and biophotovoltaic fuel cells. However, complicated fabrication, long measurement time, and low sensitivity remain the greatest challenge due to the minimal amount of bioelectricity generated from whole-cell microalgae. Herein we report the novel concept of a microalgae living biosensor by enhancing photocurrent through nanocavities formed between copper (Cu) nanoparticles and the Cu-electrode beneath. The strong energy coupling between plasmon cavity modes and excited photosynthetic fluorescence from Chlorella demonstrated that photoelectrical efficiency could be significantly amplified by more than two orders of magnitude through nanocavity confinement. Simulation results reveal that substantial near-field enhancements could help confine the electric field to the electrodes. Finally, the microalgae sensor was exploited to detect various light and heavy metal ions with a breakthrough detection limit of 50 nM. This study is envisioned to provide inspirational insights on nanocavity-enhanced electrochemistry, opening new routes for biochemical detection, water monitoring, and sustainable optoelectronics.

众所周知，金属离子在生物中扮演着各种角色。因此，检测水资源中的金属离子对于监测健康和环境状况至关重要。与人工制造的材料和设备相比，已经开发出了诸如微藻之类的生物友好型材料，用于通过利用荧光发射和生物光伏燃料电池来检测有毒化学物质。然而，由于全细胞微藻产生的生物电量最少，复杂的制造，较长的测量时间和较低的灵敏度仍然是最大的挑战。本文中，我们通过增强通过铜（Cu）纳米颗粒和下方的Cu电极之间形成的纳米腔的光电流，报告了微藻类生物传感器的新颖概念。小球藻表明，通过纳米腔的限制，光电效率可以显着提高两个数量级以上。仿真结果表明，实质性的近场增强可以帮助将电场限制在电极上。最终，微藻传感器被用于检测各种轻金属和重金属离子，突破性检测极限为50 nM。可以预见，这项研究将为纳米腔增强电化学技术提供启发性的见解，为生化检测，水监测和可持续的光电子学开辟新的途径。