SENSORS: Arrayed Optical Detection of Nanoscale Biomass

该传感器方案侧重于检测少量物质的能力，包括病原菌和细胞反应所必需的生物分子。对于质量变化的传感问题和片上多路复用和多路分解问题，提出了新的方法。这些想法是基于为先进的MEMS和集成光学设备开发的概念。目前的大多数检测技术要么笨重，要么昂贵，要么速度慢。我们提出了一种新型的超灵敏检测材料分子量的装置/仪器，应用于病原体和生化检测、医学、药物发现和纳米技术。所提出的技术允许通过光纤连接的结构来检测本质上联网的结构中的不同目标阵列。该技术通过使用一次性无源芯片来实现高产量和低成本。该器件由基于绝缘体上硅的芯片组成，该芯片将超灵敏纳米机械悬臂与新型硅基无源集成光学元件结合在一起。无源光环谐振器用于光信号的片上波长复用和解复用。环形谐振器充当不同波长的过滤器，这些过滤器被引导到不同的悬臂梁传感器。悬臂梁波导用于运动检测。在MHz范围内的机械振动由生物敏感悬臂换能器阵列中的一个元件编码在光信号上。各个波长与不同悬臂传感器的机械振动一对一的关联使人们能够定位每个感应点。这种转换策略的创新允许使用不需要外部调谐或闭环控制的环形谐振器。此外，该策略需要用于光载波信号的廉价宽带源。可以在外部设备上并行地检测在每个环形谐振器/悬臂对处检测到的振动频率的移动。该生物传感器的工作原理是基于病原体高度敏感、免疫特异性地附着在硅纳米砖结构上。除了检测病原体的存在外，还测量了病原体的质量。我们的初步结果表明，悬臂能够探测到从象形图到象形图范围内的质量。质量的附加信息使人们能够筛选假阳性，大大提高了方法的效率。IC兼容制造技术使一次性芯片的成本真正降至最低。这种方法使高分辨率测量各种病原体的干质量成为可能，从大型单细胞生物体到病毒和大分子。这一新颖的硅基纳米光子运动检测方案允许此类设备的阵列形成完整的硅平台，从而降低成本、提高灵敏度和巨大的系统级集成，使功能、成本和便携性发生革命性变化。广泛影响这项研究将使廉价紧凑型测试的大规模可访问性成为可能，目前仅在少数专业实验室完成。这将有助于预防和诊断当今的疾病和生物危险材料。例如，人们可以设想，战场上的士兵在口袋里装着传感器，可以检测到用于生物武器的非常微量的危险化学品，或者在医生的办公室或家里，病人自己使用一次性传感器，对疾病进行极其灵敏的监测。

AbstractIntellectual MeritThis Sensor proposal focuses on the ability to detect small amounts of materials, including pathogenic bacteria and biomolecules integral to cell responses. New approaches are proposed to the problems of transducing mass changes and to the problems of on-chip multiplexing and demultiplexing. These ideas are based on concepts developed for advanced MEMS and integrated optic devices. Most current detection technologies are either, bulky, expensive or slow. We propose a novel device/instrument for ultra-sensitive detection of molecular amounts of material with applications in pathogen and biochemical detection, medicine, drug discovery, and nanotechnology. The proposed technology allows the detection of an array of different targets in an intrinsically networked structure through fiber-optically linked structures. The technology lends itself to high throughput at low cost through use of disposable passive chips.The device consists of a silicon-on-insulator based chip that incorporates ultra-sensitive nano-mechanical cantilevers with novel silicon-based passive integrated optics. Passive optical ring-resonators are used for on-chip wavelength multiplexing and demultiplexing of optical signals. The ring-resonators act as filters for different wavelengths, which are guided to different cantilever sensors. The cantilever waveguide is used for motion detection. Mechanical vibrations in the MHz range are encoded on the optical signal by one element of an array of biosensitized cantilever transducers. The one-to-one association of individual wavelengths with mechanical vibrations of different cantilever sensors allows one to address each sensing site. This innovation in transduction strategy allows the use of ring-resonators that do not need external tuning or closed-loop control. Furthermore, this strategy requires inexpensive broadband sources for optical carrier signals. The sensed shift in vibration frequency at each ring resonator/cantilever pair can be detected in parallel on the external device. The principle of operation of the biosensor is based on highly-sensitive, immunospecific attachment of pathogens to silicon nanofabricated structures. In addition to detecting its presence, the mass of the pathogen is also measured. Our preliminary results show that the cantilevers are able to detect mass in the attograms to picograms range. The additional information of the mass allows one to screen for false positives, greatly increasing the efficiency of the method. The IC compatible fabrication technology allows the cost to be truly minimized for the disposable chip. Emerging from this method is the possibility of high resolution measurements of the dry mass of a great variety of pathogens, from large unicellular organisms to viruses and large macromolecules. This novel Si-based nanophotonic motion detection scheme allows arrays of such devices to form a complete silicon platform for reduced cost, increased sensitivity and enormous system level integration revolutionizing functionality, cost and portability.Broader ImpactsThis research will will enable large scale accessibility for inexpensive compact tests, today only done in a few specialized laboratories. This will help prevent and diagnose diseases and bio hazardous materials of today. One could envision for example the detection of very small traces of hazardous chemicals used in biowarfare by a soldier in the field, carrying the sensor in his pocket, or extremely sensitive monitoring of a disease, in the doctor's office or at home, by the patient himself using a disposable sensor.