A facile method for microfluidic metering and transport

Accurate metering and transport of samples and reagents are a critical process in many microfluidic applications, such as biochemical analysis, diagnostics and drug delivery. However, as the liquid volume to be processed is usually rather small, its sensoring and metering remains a challenging problem. Though some studies on this issue have been reported so far, there is still much room for improvement regarding the metering accuracy, system simplicity and control flexibility. In this work, we propose a simple, automatic and cost-effective method for microfluidic metering and transport. To improve the accuracy, the geometric metering approach with hydrophobic valves of minimum dead volumes is adopted. Besides, an on-chip Bernoulli pump is designed to reduce the hardware requirement, and a pulse width modulation (PWM) scheme is used to facilitate the operation. Testing results show that for metering of 20 μL liquid, the averaged error is − 1.3%, the relative standard deviation is 0.42%. The liquid transport can also be well regulated via PWM method.