RIKEN, 2-1 Hirosawa, Wako, Saitama 351-0198, Japan.
Lab Chip. 2013 Oct 21;13(20):4033-9. doi: 10.1039/c3lc50696g. Epub 2013 Aug 9.
We demonstrate on-chip gas/liquid sensing by using the chemotaxis of live bacteria (Euglena gracilis) confined in an isolated micro-aquarium, and gas/liquid permeation through porous polydimethylsiloxane (PDMS). The sensing chip consisted of one closed micro-aquarium and two separated bypass microchannels along the perimeter of the micro-aquarium. Test gas/liquid and reference samples were introduced into the two individual microchannels separately, and the gas/liquid permeated through the PDMS walls and dissolved in the micro-aquarium water, resulting in a chemical concentration gradient in the micro-aquarium. By employing the closed micro-aquarium isolated from sample flows, we succeeded in measuring the chemotaxis of Euglena for a gas substance quantitatively, which cannot be achieved with the conventional flow-type or hydro-gel-type microfluidic devices. We found positive (negative) chemotaxis for CO2 concentrations below (above) 15%, with 64 ppm as the minimum concentration affecting the cells. We also observed chemotaxis for ethanol and H2O2. By supplying culture medium via the microchannels, the Euglena culture remained alive for more than 2 months. The sensing chip is thus useful for culturing cells and using them for environmental toxicity/nutrition studies by monitoring their motion.
我们通过使用被限制在隔离式微池中活体细菌（眼虫）的趋化性，以及通过多孔聚二甲基硅氧烷（PDMS）的气体/液体渗透，来展示芯片上的气/液感测。传感芯片由一个封闭的微池和两个沿着微池周边分开的旁路微通道组成。测试气体/液体和参考样品分别被引入两个单独的微通道中，气体/液体渗透过 PDMS 壁并溶解在微池水中，导致微池中的化学浓度梯度。通过采用与样品流隔离的封闭微池，我们成功地对 CO2 浓度低于（高于）15%的气体物质进行了定量的趋化性测量，这是传统的流动型或水凝胶型微流控装置无法实现的。我们发现对于低于（高于）15%的 CO2 浓度，存在正（负）趋化性，其中 64 ppm 是影响细胞的最小浓度。我们还观察到了对乙醇和 H2O2 的趋化性。通过微通道供应培养基，眼虫培养物保持存活状态超过 2 个月。因此，该传感芯片可用于培养细胞，并通过监测其运动来进行环境毒性/营养研究。
