Bong Ki Wan, Lee Jiseok, Doyle Patrick S
Department of Chemical Engineering, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, MA 02139, USA.
Lab Chip. 2014 Dec 21;14(24):4680-7. doi: 10.1039/c4lc00877d. Epub 2014 Oct 15.
Stop Flow Lithography (SFL) is a microfluidic-based particle synthesis method for creating anisotropic multifunctional particles with applications that range from MEMS to biomedical engineering. Polydimethylsiloxane (PDMS) has been typically used to construct SFL devices as the material enables rapid prototyping of channels with complex geometries, optical transparency, and oxygen permeability. However, PDMS is not compatible with most organic solvents which limit the current range of materials that can be synthesized with SFL. Here, we demonstrate that a fluorinated elastomer, called perfluoropolyether (PFPE), can be an alternative oxygen permeable elastomer for SFL microfluidic flow channels. We fabricate PFPE microfluidic devices with soft lithography and synthesize anisotropic multifunctional particles in the devices via the SFL process--this is the first demonstration of SFL with oxygen lubrication layers in a non-PDMS channel. We benchmark the SFL performance of the PFPE devices by comparing them to PDMS devices. We synthesized particles in both PFPE and PDMS devices under the same SFL conditions and found the difference of particle dimensions was less than a micron. PFPE devices can greatly expand the range of precursor materials that can be processed in SFL because the fluorinated devices are chemically resistant to most organic solvents, an inaccessible class of reagents in PDMS-based devices due to swelling.
停流光刻法（SFL）是一种基于微流体的颗粒合成方法，用于制造各向异性多功能颗粒，其应用范围涵盖从微机电系统到生物医学工程等领域。聚二甲基硅氧烷（PDMS）通常用于构建SFL设备，因为这种材料能够快速制作具有复杂几何形状、光学透明性和透氧性的通道。然而，PDMS与大多数有机溶剂不兼容，这限制了目前可通过SFL合成的材料范围。在此，我们证明一种名为全氟聚醚（PFPE）的氟化弹性体可以作为SFL微流体流动通道的替代透氧弹性体。我们通过软光刻制造PFPE微流体设备，并通过SFL工艺在设备中合成各向异性多功能颗粒——这是在非PDMS通道中使用氧润滑层进行SFL的首次演示。我们通过将PFPE设备与PDMS设备进行比较，来衡量PFPE设备的SFL性能。我们在相同的SFL条件下，在PFPE和PDMS设备中合成颗粒，发现颗粒尺寸差异小于一微米。PFPE设备可以极大地扩展可在SFL中处理的前驱体材料范围，因为氟化设备对大多数有机溶剂具有化学抗性，而这是基于PDMS的设备由于溶胀而无法使用的一类试剂。
