Quartz crystal microbalance with microfluidic multi-stream solution control for mineralization kinetic analysis

• QCM sensor was integrated with microfluidic solution control and optical microscopy.
• Microfluidic solution control provides parallel-stream laminar flow and a liquid–liquid interface.
• QCM sensor was analyzed in no-mass loading, biomolecule mass-loading, and rigid mass-loading.
• Laminar flow shows improved sensor response time.
• Calcium phosphate mineralization was demonstrated and analyzed with controlled precursor mixing.

We present a quartz crystal microbalance (QCM) sensor integrated with microfluidic multi-stream solution control for a variety of analysis applications, including improved studies of mineralization kinetics. The cost-effective assembly of this device and functionality of the QCM crystal in situations of rigid and viscoelastic mass loading are demonstrated. The significant advantage of this system is the control of solution mixing on-chip through the use of laminar parallel-flow which creates a liquid–liquid reaction interface at the QCM sensor. This shows improved sensor response times, due to laminar flow, of 105 Hz/min compared to 19 Hz/min for turbulent mixing in a bulk solution flow cell. This device adds to the current real-time mass measurements obtained from traditional QCM by allowing for simultaneous optical microscopy. The combination of QCM mass analysis, optical microscopy, and laminar parallel-flow to achieve a liquid–liquid reaction interface provides an analytical system well suited for the study of controlled mineralization. The microfluidic solution flow decreases non-specific mineralization and offers significant experimental control.