Funano Shun-Ichi, Ota Nobutoshi, Tanaka Yo
Laboratory for Integrated biodevice, Center for Biosystems Dynamics Research, RIKEN, 1-3 Yamadaoka, Suita, Osaka 565-0871, Japan.
Lab Chip. 2021 Jun 1;21(11):2244-2254. doi: 10.1039/d1lc00058f.
Compared with polymer microfluidic devices, glass microfluidic devices have advantages for diverse lab-on-a-chip applications due to their rigidity, optical transparency, thermal stability, and chemical/biological inertness. However, the bonding process to construct glass microfluidic devices usually involves treatment(s) like high temperature over 400 °C, oxygen plasma or piranha solution. Such processes require special skill, apparatus or harsh chemicals, and destroy molecules or cells in microchannels. Here, we present a simple method for glass-glass bonding to easily form microchannels. This method consists of two steps: placing water droplets on a glass substrate cleaned by neutral detergent, followed by fixing a cover glass plate on the glass substrate by binding clips for a few hours at room temperature. Surface analyses showed that the glass surface cleaned by neutral detergent had a higher ratio of SiOH over SiO than glass surfaces prepared by other cleaning steps. Thus, the suggested method could achieve stronger glass-glass bonding via dehydration condensation due to the higher density of SiOH. The pressure endurance reached over 600 kPa within 6 h of bonding, which is sufficient for practical microfluidic applications. Moreover, by exploiting the reversibility of this bonding method, cell recoveries after cultivating cells in a microchannel were demonstrated. This new bonding method can significantly improve both the productivity and the usability of glass microfluidic devices and extend the possibility of glass microfluidic applications in future.
与聚合物微流控装置相比，玻璃微流控装置因其刚性、光学透明性、热稳定性以及化学/生物惰性，在各种芯片实验室应用中具有优势。然而，构建玻璃微流控装置的键合过程通常涉及诸如400℃以上的高温处理、氧等离子体或过硫酸溶液处理等。这些过程需要特殊技能、设备或使用苛刻的化学品，并且会破坏微通道中的分子或细胞。在此，我们提出一种用于玻璃-玻璃键合以轻松形成微通道的简单方法。该方法包括两个步骤：将水滴放置在经中性洗涤剂清洗过的玻璃基板上，然后在室温下用夹钳将盖玻片固定在玻璃基板上几个小时。表面分析表明，经中性洗涤剂清洗的玻璃表面比通过其他清洗步骤制备的玻璃表面具有更高的SiOH与SiO比例。因此，由于SiOH密度较高，所建议的方法可通过脱水缩合实现更强的玻璃-玻璃键合。键合6小时内耐压性达到600 kPa以上，这对于实际的微流控应用而言足够了。此外，通过利用这种键合方法的可逆性，证明了在微通道中培养细胞后细胞的回收率。这种新的键合方法可以显著提高玻璃微流控装置的生产率和可用性，并扩展未来玻璃微流控应用的可能性。
