Park Jaewon, Kim Hyun Soo, Han Arum
Department of Electrical and Computer Engineering, Texas A&M University, College Station, TX 77843-3128.
J Micromech Microeng. 2009 May 20;19:65016. doi: 10.1088/0960-1317/19/6/065016.
A poly(dimethylsiloxane) (PDMS) patterning method based on a photoresist lift-off technique to make an electrical insulation layer with selective openings is presented. The method enables creating PDMS patterns with small features and various thicknesses without any limitation in the designs and without the need for complicated processes or expensive equipments. Patterned PDMS layers were created by spin-coating liquid phase PDMS on top of a substrate having sacrificial photoresist patterns, followed by a photoresist lift-off process. The thickness of the patterned PDMS layers could be accurately controlled (6.5-24 µm) by adjusting processing parameters such as PDMS spin-coating speeds, PDMS dilution ratios, and sacrificial photoresist thicknesses. PDMS features as small as 15 µm were successfully patterned and the effects of each processing parameter on the final patterns were investigated. Electrical resistance tests between adjacent electrodes with and without the insulation layer showed that the patterned PDMS layer functions properly as an electrical insulation layer. Biocompatibility of the patterned PDMS layer was confirmed by culturing primary neuron cells on top of the layer for up to two weeks. An extensive neuronal network was successfully formed, showing that this PDMS patterning method can be applied to various biosensing microdevices. The utility of this fabrication method was further demonstrated by successfully creating a patterned electrical insulation layer on flexible substrates containing multi-electrode arrays.
本文提出了一种基于光刻胶剥离技术的聚二甲基硅氧烷（PDMS）图案化方法，用于制作具有选择性开口的电绝缘层。该方法能够创建具有微小特征和各种厚度的PDMS图案，在设计上没有任何限制，也无需复杂的工艺或昂贵的设备。通过在具有牺牲光刻胶图案的基板上旋涂液相PDMS，然后进行光刻胶剥离工艺来创建图案化的PDMS层。通过调整诸如PDMS旋涂速度、PDMS稀释比例和牺牲光刻胶厚度等工艺参数，可以精确控制图案化PDMS层的厚度（6.5 - 24 µm）。成功制作出了尺寸小至15 µm的PDMS特征，并研究了每个工艺参数对最终图案的影响。对有无绝缘层的相邻电极之间进行的电阻测试表明，图案化的PDMS层作为电绝缘层能正常发挥作用。通过在该层上培养原代神经元细胞长达两周，证实了图案化PDMS层的生物相容性。成功形成了广泛的神经网络，表明这种PDMS图案化方法可应用于各种生物传感微器件。通过在包含多电极阵列的柔性基板上成功创建图案化的电绝缘层，进一步证明了这种制造方法的实用性。
