التفاصيل البيبلوغرافية
| العنوان: |
Towards electrochemical diagnostics of biochemical free radical species in aqueous microliter volumes |
| المؤلفون: |
Chainani, Edward |
| المساهمون: |
Scheeline, Alexander, Bailey, Ryan C., Pearlstein, Arne J., Wieckowski, Andrzej |
| سنة النشر: |
2012 |
| المجموعة: |
University of Illinois at Urbana-Champaign: IDEALS (Illinois Digital Environment for Access to Learning and Scholarship) |
| مصطلحات موضوعية: |
acoustic levitation, levitated drop, microelectrode, free radicals, microfabrication, lithography, superoxide, microfluidics, electrochemistry, spectroscopy |
| الوصف: |
Reactive oxygen species (ROS) are free radicals often implicated in disease states. In probing related enzyme processes, reactant consumption must be minimized. Levitated drops show potential as microreactors where radicals are present as reactants or products. Solid/liquid interfaces are absent or minimized, avoiding adsorption and interfacial reaction of conventional microfluidics. Probing small volumes electrochemically requires an integrated sensor with reference, counter-, and one or more working electrodes. Microfabrication allows production of planar gold sensor microelectrodes. A design that placed eight copies of the sensor on a single wafer maximized throughput and use of available substrate area. Titanium was found to be superior to chromium in corrosion resistance while providing adequate adhesion between gold and the polyimide-passivated silicon substrate. A lithographic process using image reversal with lift-off proved superior to etching in terms of line width range, allowing resolution of narrow electrodes (<25 μm) and wider conductive paths. Photosensitive polyimide proved capable of insulating non-electroactive sensor regions, prevented the occurrence of metal delamination encountered in previous electrode designs, as well as defining active electrode areas. Laser milling detached individual electrodes from the wafer and shaped the tip for piercing the levitated drop. The resulting three-electrode sensor with microdisk gold working electrode of radius 19 μm was characterized using ferrocenemethanol in aqueous buffer. Using cyclic voltammetry, the electrochemically active surface area was estimated by combining a recessed microdisk electrode model with the Randles-Sevcik equation. Computer-controlled ballistic introduction of reactant droplets into a levitated drop was developed. Chronoamperometric measurements of ferrocyanide with the microfabricated electrode demonstrated the electrochemical monitoring of reactions in a levitated drop, as well as the feasibility of adding reactants ... |
| نوع الوثيقة: |
other/unknown material |
| اللغة: |
English |
| العلاقة: |
http://hdl.handle.net/2142/42209Test |
| الإتاحة: |
http://hdl.handle.net/2142/42209Test |
| حقوق: |
Copyright 2012 Edward T. Chainani |
| رقم الانضمام: |
edsbas.D89D938D |
| قاعدة البيانات: |
BASE |
