Ji Fang

Ji Fang
Louisiana Tech University | Louisiana Tech · Institute for Micromanufacturing

About

46
Publications
9,837
Reads
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837
Citations
Citations since 2017
0 Research Items
214 Citations
2017201820192020202120222023010203040
2017201820192020202120222023010203040
2017201820192020202120222023010203040
2017201820192020202120222023010203040
Additional affiliations
February 1992 - July 2014
Louisiana Tech University
Position
  • Senior Research Engineer, Graduate Faculty
Description
  • His research interests include microfluidic device and system, sensor, microreactor, total analysis system on a chip, optical lens system, and micro/nano fabrication technology.
November 1991 - February 1992
University of Cincinnati
Position
  • Senior Visiting Scholar
August 1965 - November 1991
Research Institute for Petroleum Processing, SINOPEC
Position
  • Senior Research Engineer, Department Head and Member of the Academic Board
Education
September 1960 - June 1965
Tianjin University
Field of study
  • Eletrical Engineering

Publications

Publications (46)
Conference Paper
Full-text available
This paper presents the detailed fabrication and baseline operational characterization of a miniature device capable of recovering waste heat for power. Waste heat to power is the process of scavenging heat from an industrial or transportation process as a result of mechanical inefficiencies and using that heat to generate useful power. To address...
Chapter
Full-text available
A novel process of casting the polydimethyl-siloxane (PDMS) microstructure with hybrid photoresists mold has been developed to fabricate the 3D microstructure. This new processing includes two parts: the 3D mother mold fabrication and PDMS casting processing. The 3D mother mold which consists of the three-dimensional partial-spherical microstructur...
Article
Full-text available
This paper describes a new capillary stop valve sealed with a modified polydimethylsiloxane (PDMS) cover. The valve is based on the control of the capillary burst pressure and uses the surface tension as a driving force which can be adjusted by the contact angle of the modified hydrophilic PDMS cover. The capillary valve and the capillary channel a...
Article
Full-text available
This paper presents a novel, highly sensitive and ultra-small fluorescent detection system, including an autonomous capillary fluid manipulation chip. The optical detector integrates a LED light source, all necessary optical components, and a photodiode with preamplifier into one package of about 2 cm × 2 cm × 2 cm. Also, the low-cost and simple pu...
Article
Full-text available
Polydimethylsiloxane (PDMS) is a popularly used nontoxic and biocompatible material in microfluidic systems, which is relatively cheap and does not break easily like glass. The simple fabrication, optical transparency and elastomeric property make PDMS a handy material to work with. In order to develop different applications of PDMS in microfluidic...
Article
Full-text available
A novel inductive technique for the detection of microcantilever displacement for sensing applications was presented. We highlight the basic structure and evaluate its characteristics with the aid of modeling and simulation. Results generated by numerical simulations using ANSOFT are compared with those obtained from an equivalent circuit model usi...
Article
Full-text available
This paper presents a novel, high sensitive and miniaturized fluorescence detection system which integrated a LED light source, all necessary optical components and a photodiode with preamplifier into one package about 2 cm x 2 cm x 2 cm especially for the applications of lab-on-a-chip, portable bio-detection system and point-of-care diagnostic sys...
Article
Full-text available
We have been investigating conversion of syngas (CO: H2) to higher alkanes (Fischer-Tropsch Process) in 5 µm and 25 µm channel microreactors coated with sol-gel encapsulated Fe/Co-nanocatalysts. These nano-metal-catalysts were incorporated into the sol-gel matrix by two methods: 1) metal nitrate solutions; 2) nano-particle metal oxides. Characteriz...
Article
Full-text available
An enzyme based biosensor was fabricated by employing a simple, inexpensive and rapid xurography fabrication process. The electrodes and channel were made from the conducting polymer poly(3,4-ethyelenedioxythiphene) poly(styrene sulfonate) (PEDOT:PSS). PEDOT:PSS was selectively deposited using a polyimide tape mask. The tape mask was peeled off fro...
Article
To effectively harvest waste heat from larger devices, a MEMS-based boiler is fabricated to boil working fluids for use in a low temperature steam system. The boiler is designed and fabricated to collect waste heat and drive working fluid phase change through novel microstructures. This boiled working fluid can then be made available for expansion...
Article
Two types of aluminum oxide (Al2O3) modified microcantilevers (MCLs) were tested for their sensitivity and reproducibility for detection of low levels of moisture. Aluminum was sputtered on the MCLs and oxidized to Al2O3 through thermal oxidation (Method I) and anodization method (Method II). Both deflection and frequency change of the MCLs were in...
Article
Ultra-sensitive and selective moisture sensors are needed in various industries for processing control or environmental monitoring. As an outstanding sensor platform, surface-stress sensing microcantilevers have potential application in moisture detection. To enlarge the deflection of the microcantilever under surface stress induced by specific rea...
Article
Full-text available
A novel microreactor with a network of omega-shaped microchannels has been designed, fabricated, and tested for enhanced chemical species mixing and reaction conversion. Fluidic and mixing properties of the omega channel reactor have been investigated by means of computational fluid dynamic (CFD) simulation. Also, a stochastic model describing part...
Article
Inductively coupled plasma (ICP) system has been widely used for anisotropic silicon etching because it offers high aspect ratio with a vertical side wall. The isotropic etching capability of the ICP system, however, has not gained much attention, even though it possesses advantages in profile control and high etching rate over wet isotropic etchin...
Article
We have demonstrated that the Al2O3-modified microcantilevers (MCLs) can be used to detect low level of moisture. The detection limit for moisture in nitrogen was 10ppm. The MCLs’ response time to moisture was less than 3min. The sensors were stable for months stored under ambient conditions. The bending amplitudes were proportional to the moisture...
Article
Full-text available
This paper reports a new design and microfabrication process for high sensing guard-armed silicon dioxide (SiO<sub>2</sub> ) microcantilever sensor, which can be widely used in chemical, environmental and biomedical applications. One sensor platform consists of two SiO<sub>2</sub> cantilever beams as the sensing and reference elements, two connecti...
Conference Paper
As an outstanding sensor platform, surface-stress sensing microcantilevers have potential application in moisture detection. To enlarge the deflection of the microcantilever under surface stress induced by specific reactions, a new SiO<sub>2</sub> microcantilever is developed which features a much lower Young's modulus than conventional Si or SiN<s...
Article
Full-text available
A variable focusing microlens chip, which has the capability of adjusting its focal length over a wide range without any mechanical driving parts, is reported in this paper. The packaged microlens chip consists of a flexible polymer lens, a fluidic chamber, an integrated sensor, and an actuator. A thermal actuator is introduced into this variable f...
Article
µThis paper reports a novel design of SiO2 microcantilever for high sensitivity sensor platform. In order to fabricate this device, a new fabrication process using isotropic combined with anisotropic dry etching to release the SiO2 microcantilever beam by ICP (Inductively Coupled Plasma) was developed and investigated. This new process not only obt...
Article
Full-text available
Alternate employment of etching gas (SF<sub>6</sub>) and deposition gas (C<sub>4</sub>F<sub>8</sub>) on an unpolished SiO<sub>2 </sub> surface in an inductive coupling plasma system generates a perfluorocarbon nanoneedle array at low pressure and at ambient temperature. The nanoneedle averages 300 nm in diameter and the nanoneedle surface has a lar...
Article
An integrated tunable microlens chip capable of adjusting its focal length over a wide range without any mechanical driving parts is reported in this paper. The packaged microlens chip consists of a flexible polymer lens, a fluidic chamber, a thermal actuator and a sensor. The focal length change is controlled by varying the voltage applied to the...
Article
Full-text available
This article uses finite element design for optimization of piezoresistive Si covered SiO2 microcantilevers. The maximum resistance changes were systematically investigated by varying piezoresistor geometries and doping concentration. Our simulation results show that both cantilever deflection displacement and ΔR/R change decrease when the thicknes...
Article
An integrated variable-focusing microlens chip with thermal actuator and sensor, which is capable of adjusting its focal length over a wide range, is reported. The packaged microlens chip consists of a flexible polymer lens, a thermal actuator, and a sensor. The focal length change is controlled by varying the voltage applied to the thermal actuato...
Chapter
Design and fabrication of microreactors and catalyst development of two reactions are described. A prototype reaction-gas phase conversion of cyclohexene to cyclohexane and benzene-has been studied extensively. The conversion is significantly improved (>90%) using silica sol-gel impregnated catalyst. An industrially relevant reaction on syngas conv...
Article
The development of a microreactor array system for screening nano-crystals and producing higher alkanes from syngas at pressure higher than one atmosphere, was discussed. The 3.1 cm x 1.6 cm silicon microreactors were fabricated using the micromachining facilities at the Institute of Micromanufacturing (IfM). Tetraethyl orthosilicate, water, ethano...
Article
Full-text available
Silicon microreactors have been coated with mixed-metal Fe−Co Fischer−Tropsch catalysts in alumina sol−gel for conversion of syngas (CO + H2) to higher alkanes. Characterization of the nanocatalysts using scanning electron microscopy, energy-dispersive X-ray, atomic force microscopy, and Brunauer−Emmett−Teller surface area measurements, packaging,...
Article
Full-text available
The principle, experiment setup and experimental results of a novel process of controlling the nanoparticle distribution in hydrogel by utilizing the theory of electrophoresis are discussed and demonstrated. The distributed nanoparticles in hydrogel changed the refractive index of the material, which provide the new application for organic gradient...
Article
Design and fabrication of microreactors and catalyst development of two reactions are described. A prototype reaction-gas phase conversion of cyclohexene to cyclohexane and benzene-has been studied extensively. The conversion is significantly improved (> 90%) using silica sol-gel impregnated catalyst. An industrially relevant reaction on syngas con...
Conference Paper
Full-text available
An integrated auto-tunable microlens chip, which is capable of adjusting its focal length over a wide range, is reported. The packaged microlens chip consists of a flexible 3D convex polymer lens, thermal actuator and sensor. The actuation mechanism based on the liquid's thermal expansion is introduced for the first time ever into an auto-tunable m...
Article
Full-text available
A novel process of casting the polydimethyl-siloxane (PDMS) microstructure with hybrid photoresists mold has been developed to fabricate the 3D microstructure. This new processing includes two parts: the 3D mother mold fabrication and PDMS casting processing. The 3D mother mold, which consists of the three-dimensional partial-spherical microstructu...
Article
Full-text available
Hard magnetic materials with high remnant magnetic moment, Mr, have unique advantages that can achieve bi-directional (push–pull) movement in an external magnetic field. This paper presents the results on the fabrication and testing of novel composite elastic permanent magnet films. The microsize hard barium ferrite powder, NdFeB powder, and differ...
Article
Full-text available
Femtomolar concentrations of hydrogen fluoride, a decomposition component of nerve agents, were detected using a SiO(2) microcantilever. The microcantilever underwent bending due to the reaction of HF with SiO(2). The microcantilever deflection increased as the concentration of HF increased. Other acids, such as HCl, had no effect on the deflection...
Article
Full-text available
A new polymer microlens with variable focusing properties is designed and fabricated. The microlens consists of a thin diaphragm with 3D convex lens, chamber and microchannel, which are made of polydimethyl-siloxane (PDMS). A novel fabrication approach has been developed to cast the PDMS microlens film using a PDMS mold. The elastomeric PDMS microl...
Article
Full-text available
SiO2 microcantilevers were developed to improve the sensitivity of microcantilever sensors. Silicon plasma dry etching technique was employed to release SiO2 cantilever from bulk silicon at high rate using an ordinary 2 μm thickness of SiO2 covered silicon wafer. The V-shaped microcantilever is 200 μm long, 25 μm wide, and 2 μm thick. The spring co...
Article
SiO2 microcantilevers were developed to improve the sensitivity of microcantilever sensors. Silicon plasma dry etching technique was employed to release SiO2 cantilever from bulk silicon at high rate using an ordinary 2�m thickness of SiO2 covered silicon wafer. The V-shaped microcantilever is 200�m long, 25�m wide, and 2�m thick. The spring consta...
Conference Paper
The hard magnetic materials with a high remnant magnetic moment, Mr, have the unique advantages that can achieve bi-directional (push-pull) movement in an external magnetic field. This paper presents the results on fabrication and testing of the novel hard magnetic silicone elastomer thin films. The micro-size hard ferrite powder, NdFeB powder and...
Article
Novel highly integrated microreactors have been fabricated on silicon in order to dehydrogenate cyclohexane to benzene. There are 12 reactor chips on one single silicon wafer. The microreactor consists of three layers, which are reaction chamber integrated with heaters and thermal sensors, separation layer integrated with cantilever flowmeters and...
Article
Novel microreactors have been fabricated on silicon in order to dehydrogenate cyclohexane to benzene. There are 12 reactor chips on one single silicon wafer. The microreactor consists of three chips, which are reaction chamber, separation membrane and reactor cap. The whole dimension of the reactor is 20 mm long, 14 mm wide and 3 mm high. As for re...
Article
An experimental system has been designed and constructed to conduct gas- solid heterogeneous catalytic reactions in microreactors. This apparatus is inteded to be used for any exothermic or endothermic reaction, including those with multiple feeds. It can be used to test the effectiveness of a microreactor design for a particular catalyst or to tes...
Article
A series of miniaturized, surface-driven rotary and linear electrostatic actuators was designed and fabricated. The finite element analysis method was used to aid in the design and analysis of the electrostatic drive mechanism. The actuators, consisting mainly of a copper-coated 200 μm-thick glass epoxy stator board and a 34 μm-thick carbon-coated...
Article
Mechatronics is the integration of electrical and electronic functions with mechanical and related functions. At the microscale, microelectromechanical systems (MEMS) strives to integrate those functions as well. Therefore micromechatronics and MEMS are basically identical in nature. The integration of technologies goes beyond an assemblage of subs...
Article
A series of millimeter-sized, addressable linear and rotary surface-driven electrostatic positioners are currently being designed and fabricated. The major components of these positioners are a thin copper-coated glass epoxy stator board and a carbon-coated polymer film slider which is placed on top of the stator board. Using modified Printed Circu...
Conference Paper
A series of surface-driven rotary and linear electrostatic microactuators are designed and prototyped. A finite element method is used to aid in the actuator design and analysis of the electrostatic drive mechanism. The actuators, with the major components being a double-side copper coated 200 μm-thick glass epoxy stator board and a 34 μm-thick car...

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