8/10/2017
- 10/10/2017, Amberstone Biosciences, LLC, The development
of a high throughput dielectricphoresis (DEP) droplet sorting system.
7/1/2016
- 8/31/2018 An automated single bacterium microbial fuel cells (MFCs)
on
electrowetting on dielectric device ($29,991, with UNLV).
Past
Projects:
9/1/2016
- 5/2/2017, Velox Biosystems (working as the team leader when I was
working in the ZhaoLab at UCIrvine). Single pan bacterium detection in
platelet enriched plasma using integrated comprehensive droplet digital
detection (IC3D).
6/5/2014
- 12/10/2014, Website/database development for 3E Promotions,
LLC.
3/1/2013
- 5/1/2014, The
development of a commercial
hunter-schmidt meta-analysis programs
based on adobe authorware &
vba (visual basic for
applications).
1/12/2012
- 4/1/2016, The following work were conducted in my graduate school.
Research
conducted in graduate school:
High
throughput microfluidics
We are experts on microfluidics. Those technologies include single
cell droplet encapsulation, high throughput droplet generation (from
AutoCAD to a real chip), on-chip sensors/actuators, detectors,
electrodes, and all other tools for on-chip laboratory automation.
Scientific instrumentation (hardware/software) being interfaced with
those sensors can be developed within a milestone-driven project.
Electrowetting is the physical phenomenon in which a polarizable liquid
droplet sees an increase in its contact angle in the presence of an
electric field. The ability to create, merge, split, and move
sub-microliter droplets on the surface of chip will increase
bio-analysis efficiency as it will reduce both the time needed to
reactions to run to completion and the volume of reactant/biological
sample required. Applications included protein sensing, DNA sequencing,
and cell sorting. Using standard CMOS chips provides a great solution
for
fabricating the micron level electrodes. With this consideration,
we utilize the ON Semiconductor’s C5X High Voltage technology to
overcome this problem. The 20V devices are giving higher voltage
limitation than that reported in previous literatures, thus we expect
moving, merging and splitting would work directly on the top layer of
the chip.
PZT
DMF Top Plate Control
An
intelligent EWOD top plate control system is proposed in this study.
The dynamic top plate is controlled by a piezoelectric (PZT) cantilever
structure. A High resolution laser displacement sensor is used to
monitor the deflection of the top plate. The gap height optimization
and the harmonic vibration significantly improve the droplet velocity
and decrease the minimum threshold actuation voltage for droplets
ranging from 0.2 無 to 2.0 無. The top plate vibration induced
actuation improvement is magnitude and frequency dependent. The maximum
droplet instantaneous velocity is around 9.3 mm/s,
which is almost 3 times faster than the droplet velocity without top
plate vibration. Small droplet rescue is also discussed and tested. The
top plate control technique reported in this study makes EWOD DMF chips
more reliable when used in the clinical point-of-care diagnostic
applications.
PCB-DMF
Capacitive Sensing
A
low-cost and high-resolution capacitive-to-digital converter integrated
circuit is used for droplet position detection in a digital
microfluidic system. A field-programmable gate array FPGA is used as
the integrated logic hub of the system for a highly reliable and
efficient control of the circuit. A fast-fabricating PCB (printed
circuit board) substrate microfluidic system is proposed. Smaller
actuation threshold voltages than those previously reported are
obtained. Droplets (3 無) are actuated by using a 200 V, 500 Hz
modulating pulsed voltage. Droplet positions can be detected and
displayed on a PCbased 3D animation in real time.
DMF
Fabrication
A
highly efficient and reliable electrowetting on dielectric (EWOD)
digital microfluidics (DMF) chip is proposed. An 8 痠 parylene C layer
is used as the dielectric material. Extra vapor-phase silane (VPS) is
introduced into the chamber and acts as an aerosol primer to enhance
the chemical adhesion to the parylene C surface. The EWOD chip can
perform droplet dispensing, merging and splitting. Dual electrode
dispensing mode (DEDM) and single electrode dispensing mode (SEDM) are
tested to investigate the dispensing volume accuracy. Small deviations
(0.0467 無 for DEDM and 0.0303 無 for SEDM) are observed for the
dispensing. Droplets from 1.5 無 to 2.3 無 are tested for the minimum
splitting voltage. Larger droplets require larger voltages to be split.
The proposed EWOD chip is promising for future point-of-care clinical
diagnostics.
Non-Parallel
DMF Devices
Droplet
transportation in a beak-like EWOD (electrowetting on dielectric) DMF
(digital microfluidics) device is investigated in this study. For a
sessile DI water droplet (4 無) on a 250 nm Teflon AF solution (1%)
coated hydrophobic surface, the droplet front edge has a smaller
contact angle variation than the rear edge when increase the applied
voltages. No ratchet-like motion is found under a top plate beak-like
vibration while there is no voltage applied to the EWOD electrode. If
there is a voltage applied to wet the surface, a subtle ratchet-like
motion is observed under the top plate beak-like vibration. The contact
angle hysteresis is presented in a new way, which is contact line
displacement hysteresis to the top plate opening angle. The contact
line displacement is an exponential function while decreasing the top
plate opening angle and a logarithmic function while increasing the top
plate opening angle, thereby this hysteresis can be modeled by classic
magnetic hysteresis methods.
Negative
Index Metamaterials
An
ultra-thin flat lens is proposed for focusing circularly polarized
light in the visible range. Anisotropic C-shaped nanoantennas with
phase discontinuities are used to form the metasurface of the lens. The
phase response of the C-shaped nanoantennas can be manipulated by
simply rotating the angle of the unit nanoantenna. A 600 nm incident
circularly polarized light is focused by the proposed techniques. Good
agreements are observed by using our MoM and a commercial FDTD software
package. The computation time spent by using MoM is approximately
10–100 times smaller than using FDTD. All the results show the proposed
nanoantenna array has a great potential for nanoscale optical
microscopy, solar cell energy conversion enhancement, as well as
integrated optical circuits
Non-Invasive
Brain Stimulation in Rodent Animals
Single-session
anodal transcranial direct current stimulation (tDCS) can improve the
learning-memory function of patients with Alzheimer’s disease (AD).
After-effects of tDCS can be more significant if the stimulation is
repeated regularly in a period. Here the behavioral and the histologic
effects of the repetitive anodal tDCS on a rat model of AD were
investigated. The behavioral and the
histological experiments indicate that the proposed repetitive anodal
tDCS treatment can protect spatial learning and memory dysfunction of
Abeta–40-lesioned AD rats.
Surface-Enhanced
Raman Spectroscopy
Periodic
broccoli-shaped Au and Ag surface-enhanced Raman spectroscopy (SERS)
arrays were fabricated by combining ordered SiO2 colloidal crystal
templates with the physical deposition technique. The SiO2 colloidal
rystal-assisted Au and Ag SERS substrates have a long-range, adjustable
periodic structure and a clean surface without incorporating any
reductants or surfactant chemicals. Different from depositing directly
on the flat substrates, the colloidal crystal-assisted nanostructure
array has a larger effective surface area under the same projected area
of laser irradiation, which exposes more “hot spots”.