School of Electrical and Computer Engineering, Cornell University, Ithaca, NY 14853, USA.
Analyst. 2014 Feb 21;139(4):742-8. doi: 10.1039/c3an01787g.
Research on birds has long played an important role in ecological investigations, as birds are relatively easily observed, and their high metabolic rates and diurnal habits make them quite evidently responsive to changes in their environments. A mechanistic understanding of such avian responses requires a better understanding of how variation in physiological state conditions avian behavior and integrates the effects of recent environmental changes. There is a great need for sensor systems that will allow free-flying birds to interact with their environment and make unconstrained decisions about their spatial location at the same time that their physiological state is being monitored in real time. We have developed a miniature needle-based enzymatic sensor system suitable for continuous real-time amperometric monitoring of uric acid levels in unconstrained live birds. The sensor system was constructed with Pt/Ir wire and Ag/AgCl paste. Uricase enzyme was immobilized on a 0.7 mm sensing cavity of Nafion/cellulose inner membrane to minimize the influences of background interferents. The sensor response was linear from 0.05 to 0.6 mM uric acid, which spans the normal physiological range for most avian species. We developed a two-electrode potentiostat system that drives the biosensor, reads the output current, and wirelessly transmits the data. In addition to extensive characterization of the sensor and system, we also demonstrate autonomous operation of the system by collecting in vivo extracellular uric acid measurements on a domestic chicken. The results confirm our needle-type sensor system's potential for real-time monitoring of birds' physiological state. Successful application of the sensor in migratory birds could open up a new era of studying both the physiological preparation for migration and the consequences of sustained avian flight.
鸟类研究在生态调查中长期以来发挥着重要作用，因为鸟类相对容易观察，而且它们较高的代谢率和昼行性习惯使它们对环境变化非常敏感。要深入了解鸟类的这种反应机制，就需要更好地了解生理状态的变化如何影响鸟类的行为，并整合近期环境变化的影响。我们非常需要传感器系统，使自由飞翔的鸟类能够与环境互动，并在实时监测其生理状态的同时，对其空间位置做出无约束的决策。我们开发了一种适合于连续实时监测未受约束的活体鸟类尿酸水平的微型针状酶传感器系统。该传感器系统由 Pt/Ir 丝和 Ag/AgCl 糊剂构建而成。尿酸酶被固定在 0.7 毫米的 Nafion/纤维素内膜的传感腔内，以最大程度地减少背景干扰的影响。传感器的响应从 0.05 到 0.6 mM 的尿酸呈线性，这跨越了大多数鸟类物种的正常生理范围。我们开发了一种双电极电位计系统，该系统驱动生物传感器、读取输出电流并无线传输数据。除了对传感器和系统进行广泛的表征外，我们还通过在一只家鸡身上采集体内细胞外尿酸测量值来演示系统的自主运行。结果证实了我们的针式传感器系统在实时监测鸟类生理状态方面的潜力。成功将传感器应用于候鸟，将开创研究候鸟生理准备和持续鸟类飞行后果的新时代。
