Electrical Engineering Department, ‡Bioengineering Department, §California NanoSystems Institute (CNSI), ∥Department of Molecular and Medical Pharmacology, and ⊥Department of Chemistry and Biochemistry, University of California, Los Angeles (UCLA), California 90095, United States.
ACS Nano. 2013 Oct 22;7(10):9147-55. doi: 10.1021/nn4037706. Epub 2013 Sep 12.
Optical imaging of nanoscale objects, whether it is based on scattering or fluorescence, is a challenging task due to reduced detection signal-to-noise ratio and contrast at subwavelength dimensions. Here, we report a field-portable fluorescence microscopy platform installed on a smart phone for imaging of individual nanoparticles as well as viruses using a lightweight and compact opto-mechanical attachment to the existing camera module of the cell phone. This hand-held fluorescent imaging device utilizes (i) a compact 450 nm laser diode that creates oblique excitation on the sample plane with an incidence angle of ~75°, (ii) a long-pass thin-film interference filter to reject the scattered excitation light, (iii) an external lens creating 2× optical magnification, and (iv) a translation stage for focus adjustment. We tested the imaging performance of this smart-phone-enabled microscopy platform by detecting isolated 100 nm fluorescent particles as well as individual human cytomegaloviruses that are fluorescently labeled. The size of each detected nano-object on the cell phone platform was validated using scanning electron microscopy images of the same samples. This field-portable fluorescence microscopy attachment to the cell phone, weighing only ~186 g, could be used for specific and sensitive imaging of subwavelength objects including various bacteria and viruses and, therefore, could provide a valuable platform for the practice of nanotechnology in field settings and for conducting viral load measurements and other biomedical tests even in remote and resource-limited environments.
纳米级物体的光学成像，无论是基于散射还是荧光，都是一项具有挑战性的任务，因为在亚波长尺寸下，检测信号的信噪比和对比度降低。在这里，我们报告了一个安装在智能手机上的现场便携式荧光显微镜平台，用于使用轻便紧凑的光机附件到手机现有的摄像头模块对单个纳米粒子和病毒进行成像。这种手持式荧光成像设备利用(i)紧凑型 450nm 激光二极管，以约 75°的入射角在样品平面上产生斜向激发，(ii)长通薄膜干涉滤光片以排除散射激发光，(iii)外部透镜产生 2×光学放大倍数，以及(iv)用于调焦的平移台。我们通过检测单独的 100nm 荧光颗粒以及用荧光标记的单个人类巨细胞病毒来测试这个智能手机启用显微镜平台的成像性能。通过对相同样品的扫描电子显微镜图像，验证了在手机平台上检测到的每个纳米物体的大小。这个重量仅约 186 克的可现场携带的荧光显微镜附件可以用于对包括各种细菌和病毒在内的亚波长物体进行特定和敏感的成像，因此可以为纳米技术在现场环境中的应用提供一个有价值的平台，甚至可以在远程和资源有限的环境中进行病毒载量测量和其他生物医学测试。
