Temperature change rate actuated bubble mixing for homogeneous rehydration of dry pre-stored reagents in centrifugal microfluidics†,Lab on a Chip

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Temperature change rate actuated bubble mixing for homogeneous rehydration of dry pre-stored reagents in centrifugal microfluidics†
Lab on a Chip ( IF 6.1 ) Pub Date : 2017-12-20 00:00:00 , DOI: 10.1039/c7lc01249g
S. Hin _{1,

2,

3,

4,

5} , N. Paust _{1,

2,

3,

4,

5} , M. Keller _{1,

2,

3,

4,

5} , M. Rombach _{4,

5,

6} , O. Strohmeier _{1,

2,

3,

4,

5} , R. Zengerle _{1,

2,

3,

4,

5} , K. Mitsakakis _{1,

2,

3,

4,

5}

Affiliation

In centrifugal microfluidics, dead volumes in valves downstream of mixing chambers can hardly be avoided. These dead volumes are excluded from mixing processes and hence cause a concentration gradient. Here we present a new bubble mixing concept which avoids such dead volumes. The mixing concept employs heating to create a temperature change rate (TCR) induced overpressure in the air volume downstream of mixing chambers. The main feature is an air vent with a high fluidic resistance, representing a low pass filter with respect to pressure changes. Fast temperature increase causes rapid pressure increase in downstream structures pushing the liquid from downstream channels into the mixing chamber. As air further penetrates into the mixing chamber, bubbles form, ascend due to buoyancy and mix the liquid. Slow temperature/pressure changes equilibrate through the high fluidic resistance air vent enabling sequential heating/cooling cycles to repeat the mixing process. After mixing, a complete transfer of the reaction volume into the downstream fluidic structure is possible by a rapid cooling step triggering TCR actuated valving. The new mixing concept is applied to rehydrate reagents for loop-mediated isothermal amplification (LAMP). After mixing, the reaction mix is aliquoted into several reaction chambers for geometric multiplexing. As a measure for mixing efficiency, the mean coefficient of variation ( [C with combining macron]

, n = 4 LabDisks) of the time to positivity (t_p) of the LAMP reactions (n = 11 replicates per LabDisk) is taken. The [C with combining macron]

of the t_p is reduced from 18.5% (when using standard shake mode mixing) to 3.3% (when applying TCR actuated bubble mixing). The bubble mixer has been implemented in a monolithic fashion without the need for any additional actuation besides rotation and temperature control, which are needed anyhow for the assay workflow.

中文翻译：

温度变化率驱动的气泡混合，用于离心微流体中干燥的预存储试剂的均匀水合†

在离心微流体中，很难避免混合室下游的阀门中的死体积。这些死体积从混合过程中排除，因此引起浓度梯度。在这里，我们提出了一种新的气泡混合概念，可以避免这种死体积。混合概念采用加热以在混合室下游的空气体积中产生温度变化率（TCR）引起的过压。主要特征是具有高流体阻力的排气孔，相对于压力变化而言，这表示低通过滤器。快速的温度升高会导致下游结构中压力的快速升高，从而将液体从下游通道推入混合室。随着空气进一步渗入混合室，气泡形成，由于浮力而上升并混合液体。缓慢的温度/压力变化通过高流体阻力通风口达到平衡，从而可以进行连续的加热/冷却循环以重复混合过程。混合后，可通过触发TCR驱动阀的快速冷却步骤将反应体积完全转移到下游流体结构中。新的混合概念适用于为回路介导的等温扩增（LAMP）进行水合试剂的再水化处理。混合后，将反应混合物等分到几个反应室中，以进行几何多路复用。作为混合效率的度量，平均变异系数（通过触发TCR驱动阀的快速冷却步骤，可以将反应体积完全转移到下游流体结构中。新的混合概念适用于为回路介导的等温扩增（LAMP）进行水合试剂的再水化处理。混合后，将反应混合物等分到几个反应室中，以进行几何多路复用。作为混合效率的度量，平均变异系数（通过触发TCR驱动阀的快速冷却步骤，可以将反应体积完全转移到下游流体结构中。新的混合概念适用于为回路介导的等温扩增（LAMP）重新水合试剂。混合后，将反应混合物等分到几个反应室中，以进行几何多路复用。作为混合效率的度量，平均变异系数（ [C与结合宏]

，得出LAMP反应阳性（t _p）的时间（每个LabDisk n = 11个重复）的时间为n = 4个LabDisk。在所述的吨_p（当使用标准摇模式混合）至3.3％（在应用时TCR致动气泡混合）从18.5％减少。气泡混合器已经以整体的方式实现，除了旋转和温度控制外，不需要任何其他的致动，而这对于化验工作流程仍然是必需的。 [C与结合宏]

更新日期：2017-12-20

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