Yu-Shih Chen

3D lobule-mimetic chip via positive Dielectrophoresis force with sinusoidal spacing poly (ethylene glycol)-diacrylate microwalls

In vitro culture and patterning of living cells to form a ordered 3D tissue is a rapidly developing technique with its applications in drug testing, co-culture studies, generating in vitro models of disease and other fields of biotechnology. This paper reports a 3D lobule-mimetic chip where in a three-dimensional lobule is constructed by using positive DEP (Dielectrophoresis) force. Positive DEP force was utilized to attract, adhere and pattern the cells on the surface of poly (ethylene glycol)-diacrylate (PEG-DA). PEG-DA-based check valve and valveless holes were designed to control the distribution of cells. A 3D lobule-mimetic chip is observed depend on this geometry microstructure and the novel cell manipulation method.

A hybrid vertical comb-drive actuator supported by flexible pdms suspensions

In this work, we proposed a hybrid PDMS-silicon electrostatic actuator with a large stroke under low driving voltages. The device features a staggered vertical comb-drive suspended by PDMS springs. Because of the flexibility of PDMS, an initial staggered displacement was naturally formed due to the self-weight of the device. Experimental results showed that the combination of polymeric springs and silicon structures enabled the large stroke of 3.73 µm at 3.5 kHz. The presented heterogeneous integration technology improves the performance and may bring new functionalities to micro-systems.

A double trapped single cell contact and interaction system via movable poly (ethylene glycol) diacrylate (PEG-DA) microstructure for immune analysis

Some subsets of immune cells execute their missions depending on cell contact and interaction, like natural killer cell and cytotoxic T lymphocyte. To understand the movement exhibited by cellular aggregates, we must understand how the local interactions between moving cells affect the collective motion. In this paper, we demonstrated a double trapped single cell chip by positive dielectrophoresis (pDEP) force with the movable poly (ethylene glycol) diacrylate (PEG-DA) for cell-cell contact microenvironment. In our design, such as S-shape channel, L-shaped double-lock and /-shaped double-lock, we could evaluate the NK cell activity in single cell level. Based on our data, we provided an easily-performed method for study the interaction of immune cells.

Cryogenic frozen device for hepatocyte culture and responses

In clinical medicine, freezing treatment has been applied to patients for years. However, the combination of the micro/nano biochip (or Lab Chip) techniques and cryogenic frozen techniques were seldom proposed in the past. This paper reports a cryogenic frozen apparatus for the study of microfluidic liver tissue mimic hepatic cords responses on three dimension hepatocyte culture chip. We designed the micro-cylinder about the height of 85 micrometer for loading hepatocyte to form three dimension tissue-mimic structures. The liver is organized into lobules which take the shape of polygonal prisms. Each lobule is typically hexagonal in cross section and is centered on the central vein. The bulk of the lobule consists of hepatocytes which are arranged into hepatic cords that are separated by sinusoid space. In liver function testing, the albumin secretion was affected 12% by freezing the hepatocyte ten minutes.

Spontaneous oscillation due to charging effect in MEMS RF switches

A spontaneous oscillation due to charging effect in an RF MEMS switch was investigated. When an RF MEMS switch opens from its contact mode, a nano-scale gap is formed and the charges accumulate between the movable and fixed electrodes, which cause a strong attractive force in the gap. The attractive force draws the electrodes to contact each other again, thus the charges are neutralized. As the charges are cyclically accumulated and dissipated, the intermittent excessive electrostatic force is generated, leading to the repeated pull-in/contact/pull-out motions at tens of kHz. The lifetime of MEMS switches was reduced because the electrode surfaces were degraded after cyclical excessive contacts by the oscillations. The spontaneous oscillation was analyzed theoretically by the extended Qucs model. The experiments were performed to validate the investigated effect of the spontaneous oscillation.

A multifunctional embryos manipulative microfluidic chip with dynamic flow resistance trapping and CO-culture with stromal cells

In order to optimize the quality of embryos culture, more factors are used to improve the quality of embryos. This microfluidic device integrates the various functions, such as the trapping mechanism of dynamic flow resistance, and co-culture embryos with human stromal cells providing the growth factors. For the main function, embryos can be manipulated by fluidic field in the G-type co-culture chamber (GCC), which can make the embryos grow better by keeping them moving when co-culturing. Its expected that the successful rate of embryos development and the quality can be improved by constructing the suitable environment to provide the physical stimulus for the embryos.

Isotropically tunable MEMS color filter by surface plasmon resonance

A tunable surface plasmon resonance (SPR) structure driven by microelectromechanical system (MEMS) is proposed and analyzed in this work. The MEMS isotropically expands the suspended SPR structures of nanometer metal disks scattered on a polydimethylsiloxane (PDMS) diaphragm, to different extents on the xy-plane; filtering the incident white light into various colors under control of applied voltage. This symmetrical MEMS design and its isotropic structure modulation of SPR prevailed other MEMS color filters in modulation capability, operation variety, and shows independency of polarization.

Four-leaf-clover-shaped immune response chip by using optoelectronic tweezers force

To study the immune system, the natural killer (NK) cell and target cell needs to contact for cell-cell interaction. Therefore, an optoelectronic tweezers (OET) complex optofluidic and four-leaf-clover-shaped (FLCS) microwells, multilayered platform was designed and fabricated to increase interaction. In this study, a novel method uses OET to attract immune cell into the dead zone. The proposed design creates a dynamic observation area with slower flow velocity enabling precise capture of immune cell into the microwells without harm, matching the simulation. Through a simple method, the preliminary data of NK cell and target cell interaction is obtained within 4 hours.

Using magnetic marked PEGDA-based cell sheets for three dimensional lobule-mimicking chip

The formation and regeneration of tissue are the result of intricate temporal and spatial coordination of numerous individual cell fate processes. It is regulated not only by cell autonomous processes but also by extracellular microenvironmental stimuli. In this study, we propose lobule-mimicking culture chips by using magnetic-mark poly (ethylene glycol) diacrylate (PEGDA)-based cell sheets (MP cell sheets). It consists of four cell sheet chambers and one stacking chamber. MP cell sheets were formed by UV light two times. Using magnetic field to manipulate MP cell sheets moving and rotating. Finally, we had stacked MP cell sheets to achieve lobule-mimetic regeneration.

Using gelatin methacrylate covering and dielectrophoresis force manipulating for lobule-mimicking culture chip in vitro

In vivo, tissue morphology pays an important role in cell single transferring and tissue function increasing. However, maintaining the mimetic cell culture microenvironment in microfluidic chip, several stresses which break the membrane of cells and damage the pattern of the tissue. In the paper, we demonstrate lobule-mimicking culture chip by using gelatin methacrylate (GelMA) covering and dielectrophoresis (DEP) force manipulating. GelMA is a photocrosslinked biocompatible material. The hydrogel material was used in chip for three purposes: precluding the damage between cells or tissue, providing a biological scaffold to keep cell growth, and supplying the nutrient to cells in diffusible situation.