为了使用微流体细胞仪对细胞精确计数, 采用紫外光刻工艺制作了能够真正实现三维聚焦功能的微流体检测芯片(微流控芯片)。使用聚二甲基硅氧烷(PDMS)进行二次倒模复制其结构以缩短微流控芯片制作周期、降低制作成本, 并进行了芯片的封装与测试。首先, 利用沉浸式光刻技术和斜曝光工艺制作了具有三维聚焦功能的SU-8微流沟道; 然后, 利用PDMS对所制作的SU-8微流沟道进行一次倒模, 得到其负模结构; 对负模结构进行表面处理后, 再进行二次倒模, 得到PDMS微流沟道; 最后, 封装PDMS微流沟道与盖片, 制得微流控芯片, 并对微流控芯片的沟道聚焦效果进行了测试。实验测试发现随着鞘流与样本流流速比不同, 得到样本流的聚焦宽度也不同。当鞘流与样本流流速比为20∶1时, 可以得到约10.4 μm的聚焦宽度。结果表明, 该芯片结构可靠, 可以满足进一步的流体聚焦检测要求。采用该方法制作的微流控芯片具有生产周期短、成本低、效率高和结构可靠的特点。

To count the cells precisely by using a microfluidic cytometer, a three-dimensional focusing microfluidic chip was designed by UV-photolithography based on SU-8 photoresist. The Polydimethyl Siloxane (PDMS) was used to cast doubly to replicate its structure and to shorten the fabrication cycle of microfluidic chip and reduce its costs. First, the PDMS was taken to fabricate a mold with a three-dimensional focusing microfluidic channel by the oblique exposure lithography of SU-8 photoresist and immersion lithography. Then, the PDMS was used to cast firstly for the SU-8 microfluidic to obtain a PDMS negative mode structure. After the negative mode structure was treated, it was casted again and the PDMS microfluidic detection channel which was consistent with that of the original mold was achieved. Finally, the PDMS microfluidic channel with a cover plate was packaged by using a certain packaging method and the microfluidic chip was obtained. Furthermore, the channel focus effect was tested. The test result shows that the focused width of sample flow changes with the different velocity ratios of sheath flow and sample flow. When the ratio of sheath flow and sample flow is 20∶1, the focused width is about 10.4 μm. The results demonstrate that the chip with the microstructure is reliable, and it meets the requirements of further fluid focus testing. The manufactured microfluidic chip by using this process has a short cycle, low costs and a high efficiency.