Insight Centre for Data Analytics, National Centre for Sensor Research, Dublin City University, Dublin 9, Ireland.
Lab Chip. 2017 May 31;17(11):2013-2021. doi: 10.1039/c7lc00368d.
A novel approach that allows control of flow in microfluidic channels with unsurpassed performance using light is described. Valve structures have been created using photoresponsive hydrogels based on spiropyran-functionalised pNIPAAm hydrogels photopolymerised around pillar structures within the channels. Valve actuation is controlled from outside the fluidic system using externally located LEDs. Highly precise and accurate flow rates can be selected by passing real-time flow rate measurements into a PID algorithm. The optimised algorithm also minimises overshoot of the selected flow rate, eliminates flow rate drift, and improves the system response time. In addition to the dramatic improvements in flow rate control, the set up enables the polymer actuation behaviour to be rapidly characterised. The power supply to the LED also provides a useful system diagnostic for monitoring the performance of the valve over time. For example, degradation in the valve actuation due to photodegradation will manifest as an increasing power requirement over time, enabling predictive failure thresholds to be established for particular actuator designs and polymer compositions.
描述了一种使用光来控制微流控通道中流动的新颖方法，该方法具有无与伦比的性能。使用基于螺吡喃功能化 pNIPAAm 水凝胶的光响应水凝胶，在通道内的支柱结构周围进行光聚合，从而创建了阀结构。阀致动通过外部定位的 LED 从流体制动系统外部进行控制。通过将实时流量测量值输入到 PID 算法中，可以选择非常精确和准确的流速。优化后的算法还最大限度地减少了所选流速的过冲，消除了流速漂移，并提高了系统的响应时间。除了在流速控制方面的显著改进外，该设置还能够快速表征聚合物致动行为。LED 的电源还提供了有用的系统诊断，用于随着时间的推移监测阀的性能。例如，由于光降解导致的阀致动退化将表现为随着时间的推移功率需求的增加，从而为特定的执行器设计和聚合物组成建立预测故障阈值。
