Emanuel
Waddell
joined the Department
of Chemistry in the Fall of 2004. He is a graduate of Morehouse
College (I.B.S., Chemistry, Physics, 1991) and Louisiana State
University (Ph.D., Analytical Chemistry, 2000). His research at
LSU was in the area of near infrared time-resolved
fluorescence.
Following the receipt of his doctorate, Dr. Waddell completed a
National
Research Council Post-Doctoral Fellowship at the National Institute of
Standards and Technology in Gaithersburg, MD where he became interested
in the laser ablation of polymer substrates and its application in
microfluidic (lab-on-a-chip) devices. Dr. Waddell is a member of
the Biotechnology and Materials Science Faculty. (vita.pdf)
Research Projects Laser Ablation and Surface
Modification of Polymer
Substrates for the Fabrication of Microfluidic Devices
Micro total
analytical systems (m-TAS)
are rapidly emerging as a means to perform rapid, chemical analysis on
small
platforms that greatly reduce time and space requirements.For example, researchers have performed the
polymerase chain reaction, oligonucleotide hybridization, chemical
warfare
agent identification, and DNA sequencing in m-TAS.Traditionally, these systems have been
fabricated in glass substrates by chemical etching.Recently, there has been increased interest
in fabricating m-TAS
in polymer substrates due to reduced costs and amenability to multiple
environments.One of the methods by
which these systems may be fabricated in polymer substrates is by laser
ablation.This technique utilizes the
output of a pulsed laser to ablate microfluidic channels in polymer
substrates.We are in the beginning
stages of a research program that explores the use of UV laser ablation
of
polymers and its application towards m-TAS and sensor
development.
Here is a
short pdf of my ten
minute PowerPoint. The blue box is a video of micromachining
performed at NIST during my postdoc.
Progress
1. A
very belated welcome to Stephen Shreeves and Madhu Narayanan.
Stephen is a senior chemistry major and joined my group last
spring. He has been studyng the modification of polycarbonate.
Recently, he presented preliminary results at the SouthEastern Regional
Meeting of the American Chemical Society. Here is a picture of him getting grilled by the dean at
the REU poster session. Madhu is a Materials
Science masters student and has been studying the modification of
polyethylene terephthalate. He joined in the Spring of 2006
also. If you think you
may be
interested in doing surface chemistry with applications towards
microfluidics, please contact me. I also have
funds to employ undergraduate students. James
McKee worked for me during the summer of 2005 under the auspices of
the Research Experience for
Undergraduates (the site is slightly out-of-date but the
application is still good and the pay is approximately $3000.00 for the
summer) If you're looking for a
research
experience, I have several projects available.
2.
Contact Angle
Measurement
System. If you've been following the development of these
pages then you know I constructed a contact angle goniomter. I
have been successful in getting the ImageJ software package to
operate. Scale
2.0 yields similar results but students seem to be more
confident using the ImageJ package. (Both of these packages are
free!) I am no longer using a programmable pump for my drop
dispensing. I have integrated my homebuilt
system with a
Rame-Hart Contact Angle Goniometer that
Krishnan Chittur (UAH Chemical
Engineering) loaned me. I replaced the telescope eyepiece with a
IEEE-1394 (firewire) Camera.
3.
Laser Ablation System.
The laser ablation system which I've
built consists of a GAM Excimer laser and a PRIOR Scientific
programmable stage. The
GAM laser is a multiple wavelength laser and is
capable of running from 193-nm, 248-nm, 308-nm, and 351-nm.
The system is presently configured to lase and micromachine at
193-nm. A programmable pulse generator is used to provide the
trigger for the
laser.
4.
Multiple Wavelength
Excimer
Lamp System. The
laboratory
has a USHIO Lamp System. The
wavelengths available include
308-nm, 282-nm, 254-nm, 222-nm, and 172-nm.
Presently, I am exploring surface modifications of various polymers
under this system. I consider this an undergraduate
training tool.
5.
Electrostatic Voltmeter. I have recently installed an
electrostatic
voltmeter that allows us to measure the surface charge on
polymer substrates. This provides another mechanism by which to
correlate surface modification with exposure to excimer
radiation. If you read the literature below, you will see that we
are interested in affecting electroosmotic flow by excimer
radiation.
6. Near Infrared Raman System. An Horiba
Jobin-Yvon near infrared confocal Raman System was installed in
February 2006. The system is capable of excitation at 633 and 785
nm. Stephen and Madhu have utilized the system to
investigate chemical changes on the surface of modified polymers.
Typically, we spin coat a quartz slide, perform a modification, and
then characterize the surface.
