A novel and simplified procedure for patterning hydrophobic and hydrophilic SAMs for microfluidic devices by using UV photolithography
A novel and simplified procedure for patterning hydrophobic and hydrophilic SAMs for microfluidic devices by using UV photolithography
复制标题
DOI：
10.1021/la053303l
复制
发表时间：
2006-09-26
期刊：
影响因子：
3.9
通讯作者：
Tardy, Jacques
中科院分区：
文献类型：
--
作者：
Besson, Eric;Gue, Anne-Marie;Tardy, Jacques
这项工作描述了如何通过结合众所周知的化学方案和标准光刻设备（365 nm）来实现微流控装置微通道内疏水和亲水区域的选择性图图化。进行了两种技术的比较。第一种技术是制备光可切割的自组装单层有机硅烷，第二种技术是在硅或玻璃衬底上光辅助接枝（365 nm）自组装单层有机硅烷。在第一种情况下，我们从携带邻硝基苯功能（疏水区）的单层开始，该单层被光化学裂解，露出羧酸基（亲水区）。问题是切割该单层所需的能量太高，反应时间超过1小时，辐照通量为50 mW/cm(2)。为了克服这一实际缺点，我们提出了另一种基于噻吩与二苯甲酮反应作为光引发剂的方法。在这种方法中，首先制备了一层巯基丙基三甲氧基硅烷（MPTS）。随后，一个碳氢链被光接枝到硫醇层上，形成疏水表面，而未修饰的硫醇表面被氧化成磺酸（亲水性区域）。我们证明了这种方法的可行性，并通过紫外接枝合成了高质量的自组装单层膜，辐照时间为30 s，波长为365 nm （50 mW/cm(2)）。通过接触角测量、x射线光电子能谱（XPS）、原子力显微镜（AFM）和多重内反射红外光谱（MIR-FTIR）对改性表面进行了表征。亲疏水表面的接触角相差达77度。我们还证明了这种方法与微流体通道内的选择性表面接枝是兼容的。
This work describes how selective patterning of hydrophobic and hydrophilic areas inside microchannels of microfluidic devices can be achieved by combining well-known chemical protocols and standard photolithography equipment (365 nm). Two techniques have been performed and compared. The first technique is based on the preparation of self-assembled monolayers of photocleavable organosilane and the second one on photoassisted grafting (365 nm) of self-assembled monolayers (SAMs) on a silicon or glass substrate. In the first case, we begin with monolayers carrying an o-nitrobenzyl function (hydrophobic area) that is photochemically cleaved, revealing a carboxylic acid group (hydrophilic area). The problem is that the energy necessary to cleave this monolayer is too high and the reaction time is more than 1 h with 50 mW/cm(2) irradiation flux. To overcome this practical disadvantage, we propose another approach that is based on the thiol-ene reaction with benzophenone as photoinitiator. In this approach, a monolayer of mercaptopropyltrimethoxysilane (MPTS) is prepared first. Subsequently, a hydrocarbon chain is photografted locally onto the thiol layer, forming a hydrophobic surface while the reminding unmodified thiol surface is oxidized into sulfonic acid (hydrophilic area). We demonstrated the feasibility of this approach and synthesized high-quality self-assembled monolayers by UV grafting with an irradiation time of 30 s at 365 nm (50 mW/cm(2)). The modified surfaces have been characterized by contact angle measurements, X-ray photoelectron spectroscopy (XPS), AFM, and multiple internal reflection infrared spectroscopy (MIR-FTIR). The difference in the contact angles on the hydrophilic and hydrophobic surfaces reached a remarkable 77 degrees. We have also demonstrated that this method is compatible with selective surface grafting inside microfluidic channels.