@article{qin_dong_lee_2017, title={AC-pulse modulated electrohydrodynamic jet printing and electroless copper deposition for conductive microscale patterning on flexible insulating substrates}, volume={43}, ISSN={["1879-2537"]}, url={http://gateway.webofknowledge.com/gateway/Gateway.cgi?GWVersion=2&SrcAuth=ORCID&SrcApp=OrcidOrg&DestLinkType=FullRecord&DestApp=WOS_CPL&KeyUT=WOS:000385603000021&KeyUID=WOS:000385603000021}, DOI={10.1016/j.rcim.2015.09.010}, abstractNote={This paper presents a novel micro-manufacturing method for fabrication of electrical features and patterns on highly insulating substrates and flexible substrates based on high-resolution AC-pulse modulated electrohydrodynamic jet (e-jet) printing of silver nanoink as seed layer followed by electroless copper deposition. Traditional ink jet printing method is limited in printing resolution which is determined by dimension of printing nozzle and dimension of droplets. Traditional e-jet printing has the disadvantage of residual charge problem especially for highly insulating substrates which cannot dredge remained charge of printed droplets, resulting in distorted electrostatic field and low printing controllability. Meanwhile, for printing of liquid phase ink, feature resolution contradicts with the required thickness, which is a key factor of conductivity of printed patterns. In this paper, a novel AC-modulated e-jet printing technique is applied to neutralize charges on substrates by switching polarity of consequent droplets for direct printing of high-resolution conductive silver patterns on insulating substrates. Electroless copper deposition is introduced in the fabrication process to solve the thickness problem of the resulting features. Variables of fabrication process, including amplitude and frequency of AC-pulsed voltage, plotting speed, curing temperature, number of layers, concentration of solution for copper growth, were identified to achieve reliable and conductive printed patterns. Sub-20 µm silver tracks with resistivity about 3.16 times of bulk silver were successfully fabricated. We demonstrated that ac-pulse modulated e-jet printing followed by electroless copper deposition can produce high resolution conductive patterns with improved thickness on insulating substrates and flexible substrates, which can be applied to direct printing and micro scale patterning for flexible electronics and wearable devices applications.}, journal={ROBOTICS AND COMPUTER-INTEGRATED MANUFACTURING}, author={Qin, Hantang and Dong, Jingyan and Lee, Yuan-Shin}, year={2017}, month={Feb}, pages={179–187} }
 @article{qin_wei_dong_lee_2017, title={Direct Printing and Electrical Characterization of Conductive Micro-Silver Tracks by Alternating Current-Pulse Modulated Electrohydrodynamic Jet Printing}, volume={139}, ISSN={["1528-8935"]}, url={http://gateway.webofknowledge.com/gateway/Gateway.cgi?GWVersion=2&SrcAuth=ORCID&SrcApp=OrcidOrg&DestLinkType=FullRecord&DestApp=WOS_CPL&KeyUT=WOS:000393881400008&KeyUID=WOS:000393881400008}, DOI={10.1115/1.4033903}, abstractNote={In this paper, a rapid prototyping method for fabrication of highly conductive micropatterns on insulating substrates was developed and evaluated. Sub-20 μm microstructures were printed on flexible insulating substrates using alternating current (AC) modulated electrohydrodynamic jet (e-jet) printing. The presented technique resolved the challenge of current rapid prototyping methods in terms of limited resolution and conductivity for microelectronic components for flexible electronics. Significant variables of fabrication process, including voltage, plotting speeds, curing temperature, and multilayer effect, were investigated to achieve reliable printing of silver tracks. Sub-20 μm silver tracks were successfully fabricated with resistivity about three times than bulk silver on flexible substrates, which indicates the potential applications of electrohydrodynamic printing in flexible electronics and medical applications, such as lab-on-chip systems.}, number={2}, journal={JOURNAL OF MANUFACTURING SCIENCE AND ENGINEERING-TRANSACTIONS OF THE ASME}, author={Qin, Hantang and Wei, Chuang and Dong, Jingyan and Lee, Yuan-Shin}, year={2017}, month={Feb} }
 @inproceedings{qin_cai_dong_lee_2016, title={Direct printing of capacitive touch sensors on flexible substrates by additive e-jet printing with silver nanoinks}, volume={139}, DOI={10.1115/msec2016-8740}, abstractNote={In this paper, techniques of direct printing of capacitive touch sensors on flexible substrates are presented. Capacitive touch sensors were fabricated by using electrohydrodynamic inkjet (E-jet) printing onto flexible substrates. Touch pad sensors can be achieved with optimized design of silver nanoink tracks. An analytical model was developed to predict touch pad capacitance, and experiments were conducted to study the effects of sensor design (e.g. number of electrodes, electrode length, and electrode distance) on the capacitance of printed coplanar capacitance touch sensors. Details of the fabrication techniques were developed to enable rapid prototype flexible sensors with simple structure and good sensitivity. The presented techniques can be used for the on-demand fabrication of different conductive patterns for flexible electronics with high-resolution and good transparency.}, number={3}, booktitle={Proceedings of the ASME 11th International Manufacturing Science and Engineering Conference, 2016, vol 1}, author={Qin, H. T. and Cai, Y. and Dong, Jingyan and Lee, Yuan-Shin}, year={2016} }
 @article{wei_qin_chiu_lee_dong_2015, title={Drop-on-demand E-jet printing of continuous interconnects with AC-pulse modulation on highly insulating substrates}, volume={37}, ISSN={["1878-6642"]}, url={http://gateway.webofknowledge.com/gateway/Gateway.cgi?GWVersion=2&SrcAuth=ORCID&SrcApp=OrcidOrg&DestLinkType=FullRecord&DestApp=WOS_CPL&KeyUT=WOS:000367698200008&KeyUID=WOS:000367698200008}, DOI={10.1016/j.jmsy.2014.07.005}, abstractNote={In this paper, we present a novel AC-pulse modulated electrohydrodynamic (EHD) jet printing technology that enables high resolution fabrication of electrical features and interconnects using the silver nanoink on highly insulating substrates. In traditional EHD jet printing, the remained charge of the printed droplets changes the electrostatic field distribution and interrupts the follow-on printing behavior, especially for highly insulating substrates having a slow charge decay rate. In this paper, a modulated AC-pulsed voltage was used for the EHD jet printing process that can alternate the charge polarity of the consequent droplets to neutralize the residue charge on the substrate. The effect of the residue charge is minimized, which enables high resolution printing of continuous patterns. With three printing parameters (e.g. pulse frequency, voltage, and duration), the EHD jet printing speed and droplet size can be controlled independently. We demonstrated that AC-pulse modulated EHD jet printing can overcome the charge accumulation challenge on highly insulating substrates, and investigated the variables of fabrication process to achieve reliable jet printing of conductive silver tracks.}, journal={JOURNAL OF MANUFACTURING SYSTEMS}, author={Wei, Chuang and Qin, Hantang and Chiu, Chia-Pin and Lee, Yuan-Shin and Dong, Jingyan}, year={2015}, month={Oct}, pages={505–510} }
 @article{qin_dong_lee_2015, title={ELECTROHYDRODYNAMIC JET PRINTING OF SILVER SEEDS: MICRO SCALE PATTERNING BY ELECTROLESS COPPER DEPOSITION}, ISBN={["978-0-7918-5682-6"]}, DOI={10.1115/msec2015-9487}, abstractNote={The paper describes a new method for micro scale patterning of highly conductive features on flexible and flat surfaces. The method uses electrohydrodynamic jet printing to deposit silver seeds on-demand that serve as catalysts for subsequent electroless deposition of copper. The electroless deposition of copper on substrates occurred only where silver seeds exist. In the study, ethylenediaminetetraacetic acid (EDTA) and triethanolamine (TEA) were used as chelating agents, and formaldehyde as reducing agent. Copper growth rate and resistivity were investigated using microscopic and profilometer to determine optimal concentration of each agents in reaction solution. The results indicated that EDTA significantly affects copper growth rate, playing an important role in complexing, while TEA in the dual-complexing system will balance deposition rate and stability of solution. Optimal temperature and time for copper deposition on silver nanoparticles were also discussed in the study. The techniques of activating substrates by selective printing and electroless metallization was successfully used to pattern on glass, and flexible polymer films, and both flat and curved substrates were used. The proposed technique was also capable of fabricating metal structures on flexible substrates with excellent conductivity. Metal filaments with resistivity four times bulk copper and thickness up to 15μm were demonstrated in the research.}, journal={PROCEEDINGS OF THE ASME 10TH INTERNATIONAL MANUFACTURING SCIENCE AND ENGINEERING CONFERENCE, 2015, VOL 1}, author={Qin, Hantang and Dong, Jingyan and Lee, Yuan-Shin}, year={2015} }
 @article{qin_wei_dong_lee_2014, title={DIRECT FABRICATION OF HIGHLY CONDUCTIVE MICRO SILVER TRACKS USING ELECTROHYDRODYNAMIC JET PRINTING FOR SUB-20 mu M MICRO-MANUFACTURING}, volume={2}, ISBN={["978-0-7918-4581-3"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-84908429027&partnerID=MN8TOARS}, DOI={10.1115/msec2014-4163}, abstractNote={This paper presents a direct fabrication method of highly conductive silver tracks with sub-20 μm microstructures on glass substrate by using electrohydrodynamic jet printing (EHDJP) with alternative current (AC) voltage. Traditional ink jet printing fabrication approaches are limited in the achievable resolution. EHDJP has been used in directly printing by generating a fine jet through a large electrical potential between nozzle and substrate. When charge accumulates on the ink meniscus at the nozzle, a fine jet down to nano scale can be generated. In the paper, we successfully applied EHDJP for fabrication of highly conductive silver tracks using AC voltage. It was the first time that sub-20 μm silver tracks were demonstrated and printed with resistivity about 3.16 times than bulk silver. The variables of fabrication process were investigated to achieve reliable jet printing of conductive silver tracks. The topography of printed tracks was characterized and verified in the study. The presented technique can be used for micro-manufacturing of three-dimensional microstructures and biomedical device fabrications.}, journal={PROCEEDINGS OF THE ASME 9TH INTERNATIONAL MANUFACTURING SCIENCE AND ENGINEERING CONFERENCE, 2014, VOL 2}, author={Qin, Hantang and Wei, Chuang and Dong, Jingyan and Lee, Yuan-Shin}, year={2014} }
 @article{wei_qin_ramirez-iglesias_chiu_lee_dong_2014, title={High-resolution ac-pulse modulated electrohydrodynamic jet printing on highly insulating substrates}, volume={24}, ISSN={["1361-6439"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-84897548526&partnerID=MN8TOARS}, DOI={10.1088/0960-1317/24/4/045010}, abstractNote={This paper presents a new high-resolution ac-pulse modulated electrohydrodynamic (EHD)-jet printing technology on highly insulating substrates for drop-on-demand fabrication of electrical features and interconnects using silver nanoink. In traditional EHD-jet printing, the remained charge of the printed droplets changes the electrostatic field distribution and interrupts the follow-on printing behavior, especially for highly insulating substrates which have slow charge decay rates. The residue charge makes the control of EHD-jet printing very challenging for high-resolution continuous features. In this paper, by using modulated ac-pulsed voltage, the EHD-jet printing process switches the charge polarity of the consequent droplets to neutralize the charge on the substrate. The effect of the residue charge is minimized, which enables high-resolution printing of continuous patterns. Moreover, by modulating the pulse frequency, voltage, and duration, the EHD-jet printing behavior can be controlled with respect to printing speed/frequency and droplet size. Printing frequency is directly controlled by the pulse frequency, and the droplet dimension is controlled by the voltage and the duration of the pulse. We demonstrated that ac-pulse modulated EHD-jet printing can overcome the long-predicated charge accumulation problem on highly insulating substrates, and potentially be applied to many flexible electronics applications.}, number={4}, journal={JOURNAL OF MICROMECHANICS AND MICROENGINEERING}, author={Wei, Chuang and Qin, Hantang and Ramirez-Iglesias, Nakaira A. and Chiu, Chia-Pin and Lee, Yuan-shin and Dong, Jingyan}, year={2014}, month={Apr} }