Chen Chuanzhao, Xu Pengcheng, Li Xinxin
State Key Lab of Transducer Technology, and, Science Technology on Micro-system Lab, Shanghai Institute of Micro-system and Information Technology, Chinese Academy of Sciences , 865 Changning Road, Shanghai 200050, China.
ACS Appl Mater Interfaces. 2014 Dec 24;6(24):21961-9. doi: 10.1021/am508120s. Epub 2014 Dec 12.
A top-down nanofabrication technology is developed to integrate multiple SAMs (self-assembled monolayers) into regioselective patterns. With ultraviolet light exposure through regioselectively hollowed hard mask, an existing SAM at designated microregions can be removed and a dissimilar kind of SAM can be regrown there. By repeating the photolithography-like process cycle, diverse kinds of SAM building blocks can be laid out as a desired pattern in one microfluidic channel. In order to ensure high quality of the surface modifications, the SAMs are vapor-phase deposited before the channel is closed by a bonding process. For the first time the technique makes it possible to integrate three or more kinds of SAMs in one microchannel. The technique is very useful for multiplex surface functionalization of microfluidic chips where different segments of a microfluidic channel need to be individually modified with different SAMs or into arrayed pattern for surface-guided fluidic properties like hydrophobicity/philicity and/or oleophobicity/philicity, etc. The technique has been well validated by experimental demonstration of various surface-directed flow-guiding functions. By modifying a microchannel surface into an arrayed pattern of multi-SAM "two-tone" stripe array, surface-guiding-induced 3D swirling flow is generated in a microfluidic channel that experimentally exhibits quick oil/water mixing and high-efficiency oil-to-water chemical extraction.
一种自上而下的纳米制造技术被开发出来，用于将多个自组装单分子层（SAMs）整合到区域选择性图案中。通过选择性镂空的硬掩膜进行紫外线曝光，可以去除指定微区域现有的SAM，并在那里重新生长出不同种类的SAM。通过重复类似光刻的工艺循环，可以在一个微流体通道中将各种SAM构建块排列成所需的图案。为了确保表面修饰的高质量，在通过键合工艺封闭通道之前，对SAM进行气相沉积。该技术首次使得在一个微通道中整合三种或更多种SAM成为可能。该技术对于微流体芯片的多重表面功能化非常有用，在微流体芯片中，微流体通道的不同部分需要用不同的SAM进行单独修饰，或者形成阵列图案以实现诸如疏水性/亲水性和/或疏油性/亲水性等表面引导的流体特性。通过各种表面导向的导流功能的实验证明，该技术已得到充分验证。通过将微通道表面修饰成多SAM“双色调”条纹阵列的图案，在微流体通道中产生表面引导诱导的三维旋流，实验表明该旋流能实现快速的油/水混合和高效的油到水的化学萃取。
