Cliff Tsai Portfolio_04272016 - HWSW

Portfolio in reverse chronological order Tsungchan Tsai (Cliff Tsai)

1

Hardware


2

Project 1 – Medical Device/Plasma Technology Development Project @ EP

Technologies LLC (2013-2014):

Rapid Inactivation of Bacterial Spores Using Plasma Activated Water:

Development, Species Identification and Sporicidal Mechanism

Project Feature: A new non-thermal plasma method to rapidly kill bacterial spores on dry surfaces

Required Skills: Plasma medicine, interaction of plasma with microbes, microbiology, plasma

chemistry, plasma engineering

Abstract: This work demonstrated that plasma activated water (PAW) can be used to achieve rapid

inactivation of C. difficile spores on dry hard surfaces as long as the powerful, short-lived aqueous

species can be produced in the vicinity of the spores. The experimental results showed that a higher

than 6 log reduction of C. difficile spores can be achieved within a 10 second exposure time. It was

found that the PAW treatments had a more rapid and efficacious sporicidal activity than the dry plasma

methods (both the direct DBD and the mini-plasmatron) likely due to the synergistic action of the

powerful, short-lived liquid-phase species (e.g., ONOOH) and the low pH. Spore coat and membrane

damage appeared to be the key sporicidal mechanism using activated droplets.

Accomplishment:

An oral presentation was given in the 22nd

International Symposium on Plasma Chemistry

Society (ISPC 22) in Belgium

A conference paper (ISPC 22 Proceedings) based on this work was published


3

Project 2 – Plasma Technology & Process Development Project @ Texas A&M

(2009-2012):

Polymer film deposition onto temperature-sensitive substrates in ambient air

conditions using a plasma jet

Project Feature: A new method/process to grow materials on living surfaces in open air conditions

using AP-PECVD

Required Skills: PECVD, plasma-material interaction, plasma chemistry, plasma engineering,

polymer engineering, FTIR, profilometer, XPS, AFM, SEM, optical emission spectroscopy (OES)

Abstract: A new system to deposit polymer films onto temperature-sensitive surfaces in open air

conditions by using an atmospheric non-thermal helium dielectric barrier discharge (DBD) plasma jet

was developed. Two distinct modes, which are diffuse mode and concentrated mode, were observed in

the plasma jet with the rising applied power. Methyl methacrylate (MMA) was employed as the

monomer for depositing PMMA films. The results showed that a high deposition rate (22 nm·sec−1

)

can be attained with a discharge power of 3.5 W and deposition temperature of 39 °C. In addition to

typical transparent PMMA films, opaque films with wrinkled microstructures can be obtained by using

the concentrated-mode plasma jet likely due to a buckling effect. High quality (RMS roughness is

0.4±0.1 nm) of the deposited transparent films was also demonstrated by SEM and AFM imaging

techniques. Similar functional groups were observed comparing pure PMMA and the films deposited

at different powers by using FTIR. XPS analysis showed that a higher power leads to higher C:O ratio

in the deposited films. Besides, the less retention of ester groups and the higher concentration of the

–CHn groups were observed with a higher plasma power. The MMA addition to the helium plasma jet

inhibited the generation of NO and OH excited species. By using this proposed polymer deposition

technique, rapid polymer film growth can be achieved on various types of temperature-sensitive

substrates (e.g., plastic, rubber, onion, and fingernail) with similar characteristic features to the

conventional polymer films.

PMMA Film

Bubbler

Finger (Floating electrode)

DBD jet

Powered

electrode

Accomplishment:

A journal paper (Plasma Processes and Polymers, vol. 8, pp. 523 (2011)) based on this work

was published

A patent based on this work was granted/issued


4


(2009-2012):

Metal film deposition onto temperature-sensitive substrates in ambient air

conditions using a plasma jet

Project Feature: A pioneer work which first demonstrated that copper films can be deposited in open

air conditions with an electrical conductivity close to that of bulk iron

Required Skills: PECVD, plasma-material interaction, plasma chemistry, plasma engineering, redox

reaction, electrical resistance measurement, profilometer, XPS, SEM, OES

Abstract: Deposition of metallic copper films were accomplished at ambient air conditions using a

helium DBD plasma jet with the addition of hydrogen (H2) and Cu(acac)2 vapor, which was sublimed

from its solid state at 90 °C. A change in the operation mode of the plasma jet was observed with the

rising applied power. Initially a diffuse mode was present at the low power. Higher power led to the

transition to a concentrated mode, in which a plasma channel with relatively high intensity was formed.

The mode change also showed dependence on the precursor temperature. When the precursor was

heated up to 100 °C, a helical mode, in which the discharge bent to form a curve and spun in the tube

around the central axis, occurred instead of the centered concentrated mode. The deposition profile

obtained by the profilometer showed that in general the as-deposited copper film is thicker at the

center and thinner toward edges. At a power of 3.0 W, a deposition rate of 8.3 nm/min and an

electrical resistivity of ≤ 1×10-7 ohm-m, which is close to that of bulk iron, can be obtained. Similar to

those copper films deposited by traditional CVD methods, the films obtained using the

He/H2/Cu(acac)2 plasma jet consisted of nano-grains (~ 50 nm in size), indicating the island growth

mechanism. The XPS results showed that the surface of the conductive portion (reddish brown region)

of the as-deposited film was mainly composed of metallic copper (60–80 at.% in total), rather than

copper oxide, whereas carbon and oxygen (20–40 at.% in total) were still observed. The

concentrations of the carbon and oxygen impurities, mainly attributed to the precursor ligands, can be

significantly reduced by applying a higher discharge power. It was also shown that a higher power led

to a lower concentration of the carbonyl groups in the film. In addition, the copper films exhibit better

stability (more resistant to corrosion), compared to the copper films deposited using thermal

evaporation. This He/H2/Cu(acac)2 DBD jet enables the copper films to be deposited on various

substrates (e.g., glass, silicon, plastic, and cardboard) at low temperature.

Accomplishment:

A patent (the same one mentioned in the previous project) based on this work was

granted/issued

A journal paper was drafted to be submitted


5

Project 4 – Plasma Physics Project @ Texas A&M (2009-2012):

Characteristics of Precursor-Dependent Multiple Breakdowns in Helium

Dielectric Barrier Discharge Jet

Project Feature: A fundamental study on plasma physics which discovered several unknown

discharge breakdown processes (e.g. multiple breakdown) in plasma jets

Required Skills: Plasma-impurity interaction, plasma physics, electrical characterization, high-speed

ICCD imaging, photomultiplier (PMT)

Abstract: Multiple-breakdown phenomenon in a helium (He) plasma jet was characterized. It was

observed that after MMA precursors were added to the plasma jet, the discharge current pulse at each

half cycle changed from a single broad pulse to multiple broad pulses when a sufficient voltage was

introduced. The number of the broad pulses in the He/MMA plasma jet increases with rising power.

There was always only one broad pulse per half cycle regardless of the applied power in the case using

pure He plasma jet. We observed that the higher the applied power the longer the pulse duration. The

experimental results from the discharge current traces, PMT traces, and ICCD images indicated that

each broad current pulse observed at the positive half cycle consists of several short-duration (1–2 s)

small current pulses which overlap. In other words, the “broadened current pulse” in the He and

He/MMA plasma jets can be deconvolved into several small pulses. Each short-duration pulse (one

breakdown) was found to result from an ionization wave front and a trailing plasma channel when the

wave travels from the anode to cathode. In both He and He/MMA cases, the number of the

short-duration pulses increases as the discharge power rises. The generation of more short-duration

current pulses (more breakdowns) causes the formation of a single broadened pulse (4–16 s) in the

He plasma jet with longer duration but several (2–3) broadened pulses (2–4 s) in the He/MMA

plasma jet. The separation of the broadened pulses in the He/MMA case is due to the higher

breakdown voltage and the faster decay of electron density in each single short-duration pulse,

compared to the case using pure helium. The fast current disappearance can be likely attributed to the

electron energy loss and attachment to the MMA and formed radicals.

Accomplishment:

A journal paper (IEEE Transactions on Plasma Science, vol. 40, pp. 2931 (2012)) based on

this work was published


6


(2009-2012):

Bacterial Growth Inhibition Using Polymer Films Deposited by Plasma Jet

Project Feature: A pioneer work which first demonstrated the feasibility of direct deposition of

coatings on biological surfaces in open air conditions for bacterial growth inhibition

Required Skills: Plasma medicine, interaction of plasma with microbes, microbiology

Abstract: The interaction of the plasma and the deposited coating with bacteria (E. coli) on agar was

experimentally investigated. MMA addition to the He DBD plasma jet enhanced the bactericidal

efficacy of the plasma jet (i.e., faster bacterial inactivation using He/MMA DBD jet was observed,

compared to that by pure He plasma). The experimental results showed that the deposited PMMA by

the plasma jet served as a barrier, which significantly inhibited the growth of the bacteria from the 2nd

inoculation in which the bacterium suspensions were directly added on top of the deposited film. The

results with various plasma treatment times showed that the bacterial growth inhibition efficacy was

influenced by the film thickness and the type of bacterial strains. With this new plasma-jet application,

we demonstrated that wounds can be not only sterilized but also protected by the deposited coatings

(like bandage) from bacterial invasion and growth. In addition, the attempt of AP-PECVD on pigskin

using both the He/MMA DBD jet and the He/H2/Cu(acac)2 DBD jet was made for preliminary study

of the plasma-tissue interaction and the features of the coatings grown on tissue. PMMA films were

successfully deposited on the pigskin and they exhibited a greater diameter than that of the glass tube,

similar to the results on the microscope slides and agar. The deposition of reddish brown copper films

with a size (~4 mm) close to the inner dimension of the glass tube on pigskin was also achieved. A

proper discharge power was required to prevent tissue damage and charring due to the excess heat

from plasma.

Accomplishment:

A journal paper (Applied Physics Letters, vol. 101, pp. 074107 (2012)) based on this work was

published


7

Project 6 – Plasma Technology, Process and Prototype Development Project @

Texas A&M (2009-2012):

Design and Development of Various Plasma Systems for Different Applications

Required Skills: Prototype design, plasma engineering, electrical engineering, mechanical

engineering, very strong hands-on skill


8

Project 7 – Equipment Engineering Project @ Academia Sinica (2008):

Reconstruction and Performance Improvement of a Ultra-High Vacuum

Molecular Beam Epitaxy System

Required Skills: Vacuum Technology, electrical engineering, mechanical engineering, 3rd

party

coordination capability, very strong hands-on skill

Project Summary:

Dissembled, cleaned, reconstructed, and upgraded a MBE system which had severe oil

contamination

Tested vacuum leakage on all the flanges and baked out the chamber to release the adsorbed

particles.

Accomplishment:

The upgraded MBE can reach down to 10-10

Torr and can be used to grow materials with low

evaporation temperature


9

Project 8 – Nanomaterial Fabrication & Characterization Project @ Academia

Sinica (2008-2009):

Fabrication of Semiconductor Nanostructures and Characterization of Their

Room-Temperature Ferromagnetism

Project Feature: Non-magnetic semiconductor materials may exhibit magnetic properties when their

dimensions are in several nanometers

Required Skills: PVD, material science, molecular beam epitaxy (MBE), ultra-high vacuum

technology, nano-technology, XRD, SEM, AFM, vibrating sample magnetometer (VSM), SQUID

magnetometer

Abstract: In this study, room-temperature ferromagnetism was measured in amorphous germanium

(Ge) nanoparticles by the vibrating sample magnetometer (VSM) and SQUID magnetometer. Ge

nanoparticles with various sizes and distribution were fabricated by depositing Ge layers on top of

silica nanospheres. The sizes and the distributions of Ge nanoparticles were manipulated by the sizes

of the silica nanospheres and the thickness of the Ge layers. Different Ge nanoparticles were also

collected by adjusting the helium gas pressures in inert gas condensation. The magnetization of

samples was influenced by both the size and the density of Ge nanoparticles. Larger saturation

magnetizations were observed in the sample with smaller size of Ge nanoparticles. As the density

was increased, the magnetic coupling among Ge nanoparticles was enhanced due to reduced

interparticle distances. The appearance of room-temperature ferromagnetism was attributed to the

magnetic coupling among Ge nanoparticles, in which magnetic moments may arise from both defects

in amorphous structures and the surface effect of nanoparticles. By capping a metal layer over the Ge

nanoparticles, the magnetizations were also increased through the enhancement of the magnetic

coupling. Further investigation of the room-temperature ferromagnetism in the nanostructures of

different semiconductor materials, such as Si, Sb and Bi, was also conducted. Preliminary results

showed that Si and Sb nanostructured fabricated on nanospheres also exhibited room-temperature

ferromagnetism.

Accomplishment:

A journal paper (Taiwan Nano Newsletter, vol. 18, pp. 40 (2009)) related to this work was

published


10

Project 9 – CMOS-MEMS Design & Capacitive Sensing Project @ National Tsing

Hua University (2006):

Design of a 2-D Verical Comb-Drive Micromirror with Differential Capacitance

Sensing Circuit

Project Feature: A new 2-D micromirror design which integrated the differential capacitance sensors

using CMOS-MEMS technology

Required Skills: CMOS, MEMS, semiconductor process, Cadence Tool, CoventorWare, HSPICE

Abstract: A new two-dimensional vertical comb-drive micromirror with integrated differential

capacitance sensing circuit, which is based on the TSMC 0.35 µm 2P4M Mixed Signal CMOS-MEMS

process, was designed and analyzed. In this design, the metal layers including Metal-1, Via12, and

Metal-2 were employed to form the lower comb electrodes; while Metal-3, Via34, and Metal-4 were

utilized for the upper comb electrode. Not all the comb electrodes were used for micromirror actuation.

Instead, some lower comb electrodes served as the capacitance sensing elements. Additional upper

comb electrodes were designed to achieve the differential capacitance sensing capability. When a

positive potential was applied to the outer actuators and the gimbal was grounded, the gimbal started

to rotate, leading to an increase in the capacitance of lower sensing comb electrodes and a decrease in

the capacitance of upper sensing comb electrodes. Furthermore, the differential capacitance can be

obtained. A Correlated Double Sampling (CDS) differential capacitance sensing circuit was also

designed to convert the differential capacitance to a voltage output. The voltage output can be used not

only to calculate the rotation angle but also to achieve feedback control. The CDS sensing circuit can

effectively reduce the flicker noise, offset voltage, switch charge injection, clock feedthrough and

kT/C noise. The analytical results showed that rotation angles of ±1° and ±0.72° with respect to the

mirror- and gimbal- axis can be obtained. A change in the rotation angle led to a change in the

capacitance (120-130 fF) of the sensing electrodes, which led to a voltage change ranging from -7 to 2

V at the output of the CDS differential capacitance sensing circuit based on the HSPICE simulation

results.


11

Project 10 – CMOS-MEMS Design & Fabrication Project @ National Tsing Hua

University (2004-2006):

Design and Fabrication of Two-Dimensional Vertical Comb-Drive Micromirrors

in an Optical-Tweezers System

Project Feature: Design of new 2-D micromirrors based on CMOS-MEMS fabrication process,

which facilitates the integration of the readout circuit with MEMS

Required Skills: CMOS, MEMS, semiconductor process, Cadence Tool, CoventorWare, ANSYS,

SEM, wet & dry etching, 3-D interferometer

Abstract: A novel CMOS two-dimensional (2-D) gimbaled angular vertical comb-drive (AVC)

micromirror with curled-hinged structures and an octagonal-shaped mirror was designed for the

application in an optical-tweezers system. The 2-D mirror is fabricated by TSMC 0.35 µm 2P4M Mixed

Signal CMOS-MEMS process followed by a subsequent wet etching technique. The CMOS 2-D

micromirror has the advantages of low cost, high fill factor, and capability of integration with readout

circuit. The analytical and modeling results showed that the proposed mirror has larger rotation angles,

compared to the conventional rectangular staggered vertical comb-drive (SVC) micromirrors. Rotation

angles of ±2.1° and ±1.8° with respect to the mirror- and gimbal- axis can be achieved in this AVC

octagonal 2-D micromirror.

Accomplishment:

Published a conference paper on the design of the CMOS-MEMS micromirror


12

Software


13

Project 1 – User Interface Design & Data Processing Project:

Tool Path Modification for 3D Printing

Project Feature: A Windows desktop application software to automatically modify G code file

Required Skills: C++ programming, MFC, data structure, data processing, file I/O, machine code

Abstract: This application was developed to modify tool paths for 3D printing processes. The whole

concept can be illustrated by the figure below. The original tool paths are just very simple 90 degree

paths: 12 in x+ direction, 23 in y+ direction, 34 in x- direction, 45 in y+ direction, and so on

so forth. The label E along the lines means that when the printer extrusion head moves from one point

to another, it will extrude filaments. The new paths after modification are a little bit different. Instead

of starting from point 1, the printing head starts from a point (point 1-pre) which has some distance

away from point 1. And when the printing head moves from 1-pre to 1, no filament is extruded. And

then from 1 to 2, similar to the original paths, the extrusion will be turned on. After extrusion when the

tool head arrives point 2, the extrusion will stop but keep moving to point 2-post. This application

allows the user 1) to import a file with .gcode format, 2) to tune the overshoot distance and moving

speeds during the overshoots, and 3) to export a new file with modified G code.

*Please visit https://clifftsai.wordpress.com/ for more detailed information

https://clifftsai.wordpress.com/


14

Project 2 – User Interface Design Project:

Sales Log Interface

Project Feature: A Windows desktop application software to allow the user to record, manage, and

track sales information

Required Skills: C++ programming, MFC, GUI design, data processing, file I/O, sorting using text

callbacks

Abstract: This application was developed to allow the user to manage the sales information more

efficiently. It has edit boxes to receive the information about the sales items and a main list control to

display the items with their detailed information the user types in. The main list control also has a sort

function which will be enabled when the user clicks the column header. There is a second list control

to show the dimension, weight, and price for the box used for international shipping. Both list controls

allow the user to add, update, and remove items. The application will calculate the total expense, the

total income, and the net profit automatically. The item information on the list can be further saved to a

file, which can be loaded back whenever the user wants to. In addition, this application has printing

function, which allows the user to print a summary report.

*Please visit https://clifftsai.wordpress.com/ for more detailed information

https://clifftsai.wordpress.com/


15

Project 3 – Control System Development & User Interface Design Project:

Control of Two-Dimensional Vertical Comb-Drive Micromirrors in an

Optical-Tweezers System

Project Feature: Design of a nonlinear control for 2-D veritical comb-drive micromirrors and an

image processing interface for cell recognition in the optical-tweezers system using

MATLAB/Simulink

Required Skills: MATLAB, Simulink, controller design, mathematical modeling of physical systems,

image processing

Abstract: A nonlinear controller for MEMS vertical comb-drive micromirrors, which were used in an

optical-tweezers system to control the optical tweezers, was designed. The controller combines

adaptive control and sliding control to deal with parametric uncertainties and nonlinear torque inherent

in the vertical comb-drive micromirrors, respectively. With the nonlinear controller, the vertical

comb-drive micromirrors can be operated linearly and robustly. The simulation results show that the

micromirror integrated with the proposed controller can follow a desired trajectory of 10-Hz sinusoid

with tracking error of less than 0.001° in 0.01 seconds. In addition, an image processing user interface

was designed and developed for cell recognition in the optical-tweezers system. The user interface was

used to generate the desired trajectory to the nonlinear control. It also had capabilities for automatic

cell recognition, path planning for a single laser spot, object position display, and manual operation.

Accomplishment:

Published a conference paper on the control of the CMOS-MEMS micromirror


16

Project 4 – User Interface Design & Process Simulation Project:

Design and Development of a Computer-Aided Manufacturing (CAM) Graphic

User Interface (GUI) for an Excimer Laser Based Submicron Fabrication System

Project Feature: Developed a CAM GUI software which can display the simulated fabrication

animation and result for an excimer laser submicro-machining system

Required Skills: C++/MFC programming, interpolation, fabrication path planning, data processing,

OpenGL, slicing

Abstract: A computer-aided manufacturing (CAM) software with a graphic user interface (GUI) was

designed and developed using C++ with MFC library. The CAM software was used to generate

machining codes for an excimer laser based submicron fabrication system, whose application was to

manufacture metallic free-form micro-molds. The GUI allowed users to import STL model and input

the fabrication parameters, such as laser spot size, laser wavelength, stage travel speed, and material

removal rate. Furthermore, this software has the capability to display the animation of the simulated

fabrication process and show the final appearance of the laser-fabricated micro-mold.

Accomplishment:

3rd place in the National Contest of Student Project

Documents

Cliff Tsai Portfolio_04272016 - HWSW