Three-dimensional chemotaxis model for a crawling neutrophil

Study for Laser Controlled Fabrication of Micro/Nano-Structures of Silicon Based on Multi-Physics Model

This work proposes a detailed process of micro/nano-structure surface modification in relation to temperature field. In this paper, a femtosecond laser is used to induce the surface morphology of a silicon substrate. We provide a new method for the fabrication of a micro/nano-cantilever probe by controlling the aspect ratio of the silicon surface morphology. A computational method is used to investigate the mechanical behaviors of early perturbation to late-stage structure. A diffuse interface model is employed to describe the evolution and provide a general framework. The theoretical model of femtosecond laser control surface morphology is verified by the experiments. For systematic study, the model involves the interface energy and kinetics of diffusion. This method provides an effective way to improve the sensitivity of micro/nano-cantilever sensors.

Adjustable and Versatile 3D Tumor Spheroid Culture Platform with Interfacial Elastomeric Wells

Three-dimensional (3D) cell culture platforms have recently received a great deal of attention, as these systems are able to recapitulate the in vivo microenvironment of tissues or tumors. Herein, we describe adjustable and versatile elastomeric well structures for spheroid formation and their use for in situ analyses as a tunable 3D cell culture platform. Elastomeric spherical wells are fabricated using a one-step interfacial reaction between aqueous droplets on immiscible liquid polydimethylsiloxane (PDMS) without any template or expensive equipment. Because of their differing surface tensions, spherical wells are spontaneously formed on liquid PDMS with various sizes and curvatures that are easily controlled. Using arrays of these optimized wells, single tumor spheroids within each well were successfully formed at high efficiency (up to 97%) by coculturing tumor cells and fibroblasts to reflect the complex microenvironment of cancer tissue. Moreover, the tumor spheroids formed within the interfacial wells were directly applied for observing drug responses and monitoring reactive oxygen species (ROS) to investigate tumor cell responses to drugs or their 3D microenvironment. We believe that our proposed platform provides a significant contribution to the multimodal analyses of anticancer therapeutics and the tumor microenvironment.

Hollow Microtube Resonators via Silicon Self-Assembly toward Subattogram Mass Sensing Applications

Fluidic resonators with integrated microchannels (hollow resonators) are attractive for mass, density, and volume measurements of single micro/nanoparticles and cells, yet their widespread use is limited by the complexity of their fabrication. Here we report a simple and cost-effective approach for fabricating hollow microtube resonators. A prestructured silicon wafer is annealed at high temperature under a controlled atmosphere to form self-assembled buried cavities. The interiors of these cavities are oxidized to produce thin oxide tubes, following which the surrounding silicon material is selectively etched away to suspend the oxide tubes. This simple three-step process easily produces hollow microtube resonators. We report another innovation in the capping glass wafer where we integrate fluidic access channels and getter materials along with residual gas suction channels. Combined together, only five photolithographic steps and one bonding step are required to fabricate vacuum-packaged hollow microtube resonators that exhibit quality factors as high as ∼ 13,000. We take one step further to explore additionally attractive features including the ability to tune the device responsivity, changing the resonator material, and scaling down the resonator size. The resonator wall thickness of ∼ 120 nm and the channel hydraulic diameter of ∼ 60 nm are demonstrated solely by conventional microfabrication approaches. The unique characteristics of this new fabrication process facilitate the widespread use of hollow microtube resonators, their translation between diverse research fields, and the production of commercially viable devices.

Multiphysics and Multiscale Analysis for Chemotherapeutic Drug

This paper presents a three-dimensional dynamic model for the chemotherapy design based on a multiphysics and multiscale approach. The model incorporates cancer cells, matrix degrading enzymes (MDEs) secreted by cancer cells, degrading extracellular matrix (ECM), and chemotherapeutic drug. Multiple mechanisms related to each component possible in chemotherapy are systematically integrated for high reliability of computational analysis of chemotherapy. Moreover, the fidelity of the estimated efficacy of chemotherapy is enhanced by atomic information associated with the diffusion characteristics of chemotherapeutic drug, which is obtained from atomic simulations. With the developed model, the invasion process of cancer cells in chemotherapy treatment is quantitatively investigated. The performed simulations suggest a substantial potential of the presented model for a reliable design technology of chemotherapy treatment.