Towards bioelectronics: Charge carrier transport properties and structure of eumelanin thin films

黑色素存在于许多植物、动物、人类皮肤、头发、眼睛和大脑中，其性质类似于半导体。它能吸收强烈的可见光和紫外线，使我们的身体免受阳光的伤害。它还导电，而它的传导性强烈地依赖于湿度和温度。目前还不清楚是哪种类型的载流子，是离子还是电子，以及其潜在的机制是什么。我们将制造第一个黑色素场效应管来解决这些问题。这种结构将使我们能够确定主要的载流子，并详细地表征黑色素薄膜的电学性质。此外，黑色素薄膜的生长和结构将在纳米尺度上进行研究，以将电学性质与黑色素分子的组织联系起来，这是文献中另一个有争议的问题。黑色素的半导体特性，加上其稳定性和生物学性质，使其在紫外线保护膜、化学传感器和太阳能电池等应用中非常有趣。更好地了解黑色素的物理性质将为这些应用铺平道路。对黑色素等功能生物分子的研究有可能导致环境友好、可生物降解的技术和与人体环境兼容的医疗设备。

The pigment melanin, which can be found in many plants, animals, human skin, hair, eyes, and brain, has properties similar to a semiconductor. It absorbs strongly visible and UV light, enabling it to protect our body from sunlight. It also conducts charges, whereas its conductivity depends strongly on humidity and temperature. It is still not well understood which type of charge carriers, ions or electrons, is transported and what is the underlying mechanism. We will fabricate the first melanin field-effect transistors to address these questions. This configuration will allow us to determine the dominating charge carriers and to characterize the electrical properties of melanin thin films in detail. Additionally, the growth and structure of melanin films will be studied on a nanometer scale to relate electrical properties to the organization of melanin molecules, another issue disputed in literature. Melanin's semiconducting properties combined with its stability and biological nature make it very interesting for applications like UV-protective films, chemical sensors and solar cells. A better understanding of melanin's physical properties will pave the way for these applications. Research on functional biomolecules like melanin has the potential to result in environmentally friendly, bio-degradable technology and medical devices compatible with the environment of human body.