Zifan Tang

Fabrications, Applications and Challenges of Solid-State Nanopores: A Mini Review

Nanopore sensors are expected to be one of the most promising next generation sequencing technologies, with label-free, amplification-free and high-throughput features, as well as rapid detections and low cost. Solid-state nanopores have been widely explored due to their diverse fabrication methods and CMOS compatibility. Here, we highlight the fabrication methods of solid-state nanopores, including the direct opening and the tuning methods. In addition, molecular translocation developments, DNA sequencing and protein detections are summarized. Finally, the latest progress relating to solid-state nanopores is discussed, which helps to offer a comprehensive understanding of the current situation for solid-state nanopore sensors.

Acoustically Triggered Disassembly of Multilayered Polyelectrolyte Thin Films through Gigahertz Resonators for Controlled Drug Release Applications

Controlled drug release has a high priority for the development of modern medicine and biochemistry. To develop a versatile method for controlled release, a miniaturized acoustic gigahertz (GHz) resonator is designed and fabricated which can transfer electric supply to mechanical vibrations. By contacting with liquid, the GHz resonator directly excites streaming flows and induces physical shear stress to tear the multilayered polyelectrolyte (PET) thin films. Due to the ultra-high working frequency, the shear stress is greatly intensified, which results in a controlled disassembling of the PET thin films. This technique is demonstrated as an effective method to trigger and control the drug release. Both theory analysis and controlled release experiments prove the thin film destruction and the drug release.

A Universal Biomolecular Concentrator To Enhance Biomolecular Surface Binding Based on Acoustic NEMS Resonator

In designing bioassay systems for low-abundance biomolecule detection, most research focuses on improving transduction mechanisms while ignoring the intrinsically fundamental limitations in solution: mass transfer and binding affinity. We demonstrate enhanced biomolecular surface binding using an acoustic nano-electromechanical system (NEMS) resonator, as an on-chip biomolecular concentrator which breaks both mass transfer and binding affinity limitations. As a result, a concentration factor of 105 has been obtained for various biomolecules. The resultantly enhanced surface binding between probes on the absorption surface and analytes in solution enables us to lower the limit of detection for representative proteins. We also integrated the biomolecular concentrator into an optoelectronic bioassay platform to demonstrate delivery of proteins from buffer/serum to the absorption surface. Since the manufacture of the resonator is CMOS-compatible, we expect it to be readily applied to further analysis of biomolecular interactions in molecular diagnostics.

Bioparticle manipulations using lamb wave resonator array

We apply the Lamb wave resonators (LWRs) in microfluidic field, and design a novel MEMS device consisting of 4 LWRs, that can efficiently drive multiple cylindrical vortices and locally enrich the bioparticles in liquid. The acoustic streaming effects in the fluid induced by the LWR is deduced. A numerical simulation method to compute the acoustic streaming effect is presented, and based on which, a 3D finite element model for the LWR inducing acoustic streaming is built. An LWR array consisting of 4 resonators is designed, simulated and fabricated. The simulation model predicts the distributions of multiple micro-vortices induced by the LWR array and the concentration of the particles in the vortices. Experimentally, we demonstrate that, the LWR array device, can efficiently drive multiple horizontal cylindrical vortices in a 1 μL drop and further trapped the bioparticles at the center of the vortex, which shows a great potential for biomolecular manipulations and biosensing applications.

Directly trapping of nanoscale biomolecules using bulk acoustic wave resonators

Techniques that can manipulate micro or macro biomaterials like cells and organisms have been of interest for a wide range of applications from biochemistry to clinical diagnostics and many clever techniques have been developed. However, methods with the ability to directly manipulate nanoscale biomaterials (e.g. proteins or DNAs) are still challenging due to physical limitations like Brownian motions. Here, according to theoretical design of the stagnation point in the medium which is formed by bulk-acoustic-wave-resonator-induced acoustic streaming, we experimentally realize trapping of biomolecules characterized by length scales at nanometer. We expect bulk acoustic wave resonator (BAWR) to become a powerful tool (e.g. biosensor and bioactuator) to revolutionize the fundamental and applied research for nanoscale biomaterials manipulation.

Trapping of biomolecules using bulk acoustic wave resonators

This work highlights a new on-chip biomolecule trapping method. We systematically studied the device performance in liquid, and provide a hydrodynamic combined acoustic method to trap micro-and nano-scaled bioparticles.