A Study On Monolithic Integrated Chip With Digital Microfluidics And Film Bulk Acoustic Resonator Sensor

Lab-on-a-chip offers the ability to carry out high-resolution sample separations and detections on an integrated platform. It has been employed for a broad range of applications in biology, chemistry and medicine. Digital microfluidics, highlighting its capability of handling tiny droplet samples, fast reaction, parallel processing, and compact size, holds great promise in future high-throughput detection and point-of-care-testing.In order to address the high-density integration demand in current lab-on-a-chip R&D, a monolithic integrated chip with electrowetting-on-dielectric(EWOD) digital droplet manipulator and film bulk acoustic resonator(FBAR) sensor is proposed. The first and second generation integrated chips are successfully developed. In addition, a unique feature of signal amplification effect in the integrated chip sensing is carefully analyzed. The characterization experiments with chemical and biological samples are conducted, and preliminary results show that the integrated chips are practically effective.The main achievements of the PhD work are listed in the following:1. On the basis of previous work and extensive literature survey, the dissertation proposes sharing the same aluminium nitride thin film between the FBAR sensor and the EWOD manipulator, which is a key factor to achieve the single chip integration. The single-channel integrated chip, multi-channel integrated chip and the corresponding system are successfully demonstrated via the breakthrough in design, fabrication and testing technologies.2. Taking advantage of the unique discrete feature, the sensing of sample droplets in air environment is available. It solves the problem of severe sensor performance degradation in liquid sensing environment, and hence the signal to noise ratio is improved greatly. The LOD for mass detection is calculated to be 0.13 ng/cm2.3. The signal amplification mechanism is studied theoretically and experimentally. Over an order of magnitude improvement on LOD is monitored by masking FBAR sensors with hydrophobic film. The LODs for Hg2+, BSA and anti-IgG solutions are experimentally determined to be about 1nM. An analytical model is developed based on the diffusions and first order binding kinetics of biological target molecules in confined droplets.