Poly (methyl methacrylate) (PMMA) has become increasingly popular to fabricate microfluidic devices. In a microfluidic device, different functional areas usually require different wettability to achieve a better performance. However, most of the existing wettability modification methods have been applied to the whole PMMA surface making the device have minimum wettability difference. In this paper, a controllable gradient UV irradiation (CGUI) method was presented. In this method, a series of quartz plates sputtered with different thickness of Cu were arranged on top of the PMMA surface. By controlling the thickness of Cu film, the UV irradiation, which transmitted though the quartz plates onto the PMMA surface, can be adjusted making the modification performance able to be varied accordingly. The validation of the proposed CGUI was conducted through contact angle measurements. Our results showed that through 5 min CGUI process, the contact angle for different parts of the PMMA surface can be varied from 45.48° to 77.41° continuously with a long-term stability of 60 days. To demonstrate this method, a fully integrated Point-of-Care Test (POCT) device was designed and fabricated for the detection of cardiac Troponin I achieving the lower detection limit of 85 pg/ml within 10 min.

聚（甲基丙烯酸甲酯）（PMMA）在制造微流体装置中变得越来越流行。在微流体装置中，不同的功能区域通常需要不同的润湿性才能获得更好的性能。但是，大多数现有的润湿性改进方法已应用于整个PMMA表面，从而使该器件具有最小的润湿性差异。本文提出了一种可控的梯度紫外线照射（CGUI）方法。在这种方法中，将一系列溅射了不同厚度的Cu的石英板布置在PMMA表面的顶部。通过控制Cu膜的厚度，可以调节通过石英板透射到PMMA表面上的UV辐射，从而可以相应地改变改性性能。通过接触角测量对提出的CGUI进行了验证。我们的结果表明，通过5分钟的CGUI过程，PMMA表面不同部分的接触角可以连续地从45.48°更改为77.41°，并具有60天的长期稳定性。为了证明该方法，设计并制造了一个完全集成的即时护理测试（POCT）设备，用于检测心肌肌钙蛋白I，并在10分钟内达到85 pg / ml的检测下限。