Jian Gu

Interests

Research

Platform development, medical devices and procedures

Courses

Scholarly Contributions

Chapters

• Zhang, P., Gu, J., He, J., Gao, W., Zhang, W., Lindsay, S., & Meldrum, D. R. (2011). Next-generation and future DNA sequencing technologies and metagenomics. In Metagenomics and its Applications in Agriculture, Biomedicine and Environmental Studies. Nova Science Publishers, Inc.

Journals/Publications

• Atta, S., Zhao, Y., Sanchez, S., Seedial, D., Devadhasan, J. P., Summers, A. J., Gates-Hollingsworth, M. A., Pflughoeft, K. J., Gu, J., Montgomery, D. C., AuCoin, D. P., Zenhausern, F., & Vo-Dinh, T. (2024). Plasmonic-Enhanced Colorimetric Lateral Flow Immunoassays Using Bimetallic Silver-Coated Gold Nanostars. ACS applied materials & interfaces, 16(40), 54907-54918.
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  The colorimetric lateral flow immunoassay (cLFIA) has gained widespread attention as a point-of-care testing (POCT) technique due to its low cost, short analysis time, portability, and capability of being performed by unskilled operators with minimal requirement of reagents. However, the low analytical sensitivity of conventional LFIA based on colloidal gold nanospheres limits their applications for sensitive detection of trace amounts of target analytes. In this study, we introduced a novel plasmonic-enhanced colorimetric LFIA (PE-cLFIA) platform featuring bimetallic silver-coated gold nanostars (BGNS) with exceptional optical properties, leading to ultrahigh visual color brightness. The BGNS-based PE-cLFIA was successfully applied to detect a model analyte, low-calcium response V (LcrV), a virulence protein factor found in , the causative agent of bubonic plague. The PE-cLFIA sensing using BGNS-3 composed of 45 nm silver thickness showed a high visual colorimetric sensitivity with a detection limit as low as 13.7 pg/mL, which was around 50 times more sensitive than that of a traditional gold nanoparticle-based LFIA. In addition, the antibody-conjugated BGNS-3 showed excellent stability over 6 months. To illustrate the potential for clinical applications, we demonstrated that our LFIA platform for detecting LcrV spiked in human serum without any sample preprocessing exhibited a detection limit of 22.8 pg/mL. These results open up new opportunities for developing hybrid nanoparticle systems for sensitive POCT PE-cLFIA screening for infectious disease detection.
• Jones, C. W., Overbey, E. G., Lacombe, J., Ecker, A. J., Meydan, C., Ryon, K., Tierney, B., Damle, N., MacKay, M., Afshin, E. E., Foox, J., Park, J., Nelson, T. M., Suhail Mohamad, M., Byhaqui, S. G., Aslam, B., Tali, U. A., Nisa, L., Menon, P. V., , Patel, C. O., et al. (2024). Molecular and physiological changes in the SpaceX Inspiration4 civilian crew. Nature, 632(8027), 1155-1164.
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  Human spaceflight has historically been managed by government agencies, such as in the NASA Twins Study, but new commercial spaceflight opportunities have opened spaceflight to a broader population. In 2021, the SpaceX Inspiration4 mission launched the first all-civilian crew to low Earth orbit, which included the youngest American astronaut (aged 29), new in-flight experimental technologies (handheld ultrasound imaging, smartwatch wearables and immune profiling), ocular alignment measurements and new protocols for in-depth, multi-omic molecular and cellular profiling. Here we report the primary findings from the 3-day spaceflight mission, which induced a broad range of physiological and stress responses, neurovestibular changes indexed by ocular misalignment, and altered neurocognitive functioning, some of which match those of long-term spaceflight, but almost all of which did not differ from baseline (pre-flight) after return to Earth. Overall, these preliminary civilian spaceflight data suggest that short-duration missions do not pose a significant health risk, and moreover present a rich opportunity to measure the earliest phases of adaptation to spaceflight in the human body at anatomical, cellular, physiological and cognitive levels. Finally, these methods and results lay the foundation for an open, rapidly expanding biomedical database for astronauts, which can inform countermeasure development for both private and government-sponsored space missions.
• Rabadi, I., Carpentieri, D., Wang, J., Zenhausern, F., & Gu, J. (2024). On reactive Ion Etching of Parylene-C with Simple Photoresist Mask for Fabrication of High Porosity Membranes to Capture Circulating and Exfoliated Tumor Cells. Micromachines, 15(4).
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  A high porosity micropore arrayed parylene membrane is a promising device that is used to capture circulating and exfoliated tumor cells (CTCs and ETCs) for liquid biopsy applications. However, its fabrication still requires either expensive equipment or an expensive process. Here, we report on the fabrication of high porosity (>40%) micropore arrayed parylene membranes through a simple reactive ion etching (RIE) that uses photoresist as the etching mask. Vertical sidewalls were observed in etched parylene pores despite the sloped photoresist mask sidewalls, which was found to be due to the simultaneous high DC-bias RIE induced photoresist melting and substrate pedestal formation. A theoretical model has been derived to illustrate the dependence of the maximum membrane thickness on the final pore-to-pore spacing, and it is consistent with the experimental data. A simple, yet accurate, low number (
• Devadhasan, J. P., Summers, A. J., Gu, J., Smith, S., Thomas, B., Fattahi, A., Helton, J., Pandit, S. G., Gates-Hollingsworth, M., Hau, D., Pflughoeft, K. J., Montgomery, D. C., Atta, S., Vo-Dinh, T., AuCoin, D., & Zenhausern, F. (2023). Point-of-care vertical flow immunoassay system for ultra-sensitive multiplex biothreat-agent detection in biological fluids. Biosensors & bioelectronics, 219, 114796.
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  This paper presents simple, fast, and sensitive detection of multiple biothreat agents by paper-based vertical flow colorimetric sandwich immunoassay for detection of Yersinia pestis (LcrV and F1) and Francisella tularensis (lipopolysaccharide; LPS) antigens using a vertical flow immunoassay (VFI) prototype with portable syringe pump and a new membrane holder. The capture antibody (cAb) printing onto nitrocellulose membrane and gold-labelled detection antibody (dAb) were optimized to enhance the assay sensitivity and specificity. Even though the paper pore size was relaxed from previous 0.1 μm to the current 0.45 μm for serum samples, detection limits as low as 0.050 ng/mL for LcrV and F1, and 0.100 ng/mL for FtLPS have been achieved in buffer and similarly in diluted serum (with LcrV and F1 LODs remained the same and LPS LOD reduced to 0.250 ng/mL). These were 40, 80, and 50X (20X for LPS in serum) better than those from lateral flow configuration. Furthermore, the comparison of multiplex format demonstrated low cross-reactivity and equal sensitivity to that of the singleplex assay. The optimized VFI platform thus provides a portable and rapid on-site monitoring system for multiplex biothreat detection with the potential for high sensitivity, specificity, reproducibility, and multiplexing capability, supporting its utility in remote and resource-limited settings.
• Akkad, A. R., Gu, J., Duane, B., Norquist, A., Brenner, D. J., Ramakumar, A., & Zenhausern, F. (2022). Automatic reagent handling and assay processing of human biospecimens inside a transportation container for a medical disaster response against radiation. PloS one, 17(5), e0268508.
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  Biological materials can be shipped off-site for diagnostic, therapeutic and research purposes. They usually are kept in certain environments for their final application during transportation. However, active reagent handling during transportation from a collection site to a laboratory or biorepository has not been reported yet. In this paper, we show the application of a micro-controlled centrifugal microfluidic system inside a shipping container that can add reagent to an actively cultured human blood sample during transportation to ensure a rapid biodosimetry of cytokinesis-block micronucleus (CBMN) assay. The newly demonstrated concept could have a significant impact on rapid biodosimetry triage for medical countermeasure in a radiological disaster. It also opens a new capability in accelerated sample processing during transportation for biomedical and healthcare applications.
• Harris, A. F., Lacombe, J., Sanchez-Ballester, N. M., Victor, S., Curran, K. A., Nordquist, A. R., Thomas, B., Gu, J., Veuthey, J. L., Soulairol, I., & Zenhausern, F. (2022). Decellularized Spinach Biomaterials Support Physiologically Relevant Mechanical Cyclic Strain and Prompt a Stretch-Induced Cellular Response. ACS applied bio materials, 5(12), 5682-5692.
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  Recently, decellularized plant biomaterials have been explored for their use as tissue engineered substitutes. Herein, we expanded upon the investigation of the mechanical properties of these materials to explore their elasticity as many anatomical areas of the body require biomechanical dynamism. We first constructed a device to secure the scaffold and induce a strain within the physiological range of the normal human adult lung during breathing (12-20 movements/min; 10-20% elongation). Results showed that decellularized spinach leaves can support cyclic strain for 24 h and displayed heterogeneous local strain values (7.76-15.88%) as well as a Poisson's ratio (0.12) similar to that of mammalian lungs (10.67-19.67%; 0.01), as opposed to an incompressible homogeneous standard polymer (such as PDMS (10.85-12.71%; 0.4)). Imaging and mechanical testing showed that the vegetal scaffold exhibited strain hardening but maintained its structural architecture and water retention capacity, suggesting an unaltered porosity. Interestingly, we also showed that cells seeded on the scaffold can also sense the mechanical strain as demonstrated by a nuclear reorientation perpendicular to strain direction (63.3° compared to 41.2° for nonstretched cells), a nuclear location of YAP and increased expression of YAP target genes, a high cytoplasmic calcium level, and an elevated expression level of collagen genes (COL1A1, COL3A1, COL4A1, and COL6A) with an increased collagen secretion at the protein level. Taken together, these data demonstrated that decellularized plant leaf tissues have an inherent elastic property similar to that found in the mammalian system to which cells can sense and respond.
• Summers, A. J., Devadhasan, J. P., Gu, J., Montgomery, D. C., Fischer, B., Gates-Hollingsworth, M. A., Pflughoeft, K. J., Vo-Dinh, T., AuCoin, D. P., & Zenhausern, F. (2022). Optimization of an Antibody Microarray Printing Process Using a Designed Experiment. ACS omega, 7(36), 32262-32271.
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  Antibody microarrays have proven useful in immunoassay-based point-of-care diagnostics for infectious diseases. Noncontact piezoelectric inkjet printing has advantages to print antibody microarrays on nitrocellulose substrates for this application due to its compatibility with sensitive solutions and substrates, simple droplet control, and potential for high-capacity printing. However, there remain real-world challenges in printing such microarrays, which motivated this study. The effects of three concentrations of capture antibody (cAb) reagents and nozzle hydrostatic pressures were chosen to investigate three responses: the number of printed membrane disks, dispensing performance, and microarray quality. Printing conditions were found to be most ideal with 5 mg/mL cAb and a nozzle hydrostatic pressure near zero, which produced 130 membrane disks in a single print versus the 10 membrane disks per print before optimization. These results serve to inform efficient printing of antibody microarrays on nitrocellulose membranes for rapid immunoassay-based detection of infectious diseases and beyond.
• Devadhasan, J. P., Gu, J., Chen, P., Smith, S., Thomas, B., Gates-Hollingsworth, M., Hau, D., Pandit, S., AuCoin, D., & Zenhausern, F. (2021). Critical Comparison between Large and Mini Vertical Flow Immunoassay Platforms for Detection. Analytical chemistry, 93(27), 9337-9344.
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  is a Gram-negative bacterium that is the causative agent of plague and is widely recognized as a potential biological weapon. Due to the high fatality rate of plague when diagnosis is delayed, the development of rapid, sensitive, specific, and cost-effective methods is needed for its diagnosis. The low calcium response V (LcrV) protein has been identified as a potential microbial biomarker for the diagnosis of plague. In this paper, we present a highly sensitive, paper-based, vertical flow immunoassay (VFI) prototype for the detection of LcrV and the diagnosis of plague. An antigen-capture assay using monoclonal antibodies is employed to capture and detect the LcrV protein, using a colorimetric approach. In addition, the effect of miniaturizing the VFI device is explored based on two different sizes of VFI platforms, denoted as "large VFI" and "mini VFI." Also, a comparative analysis is performed between the VFI platform and a lateral flow immunoassay (LFI) platform to exhibit the improved assay sensitivity suitable for point-of-care (POC) diagnostics. The analytical sensitivity or limit of detection (LOD) in the mini VFI is approximately 0.025 ng/mL, that is, 10 times better than that of the large VFI platform or 80 times over a standard lateral flow configuration. The low LOD of the LcrV VFI appears to be highly suitable for testing clinical samples and potentially diagnosing plague at earlier time points. In addition, optimization of the gold nanoparticle (AuNP) concentration, nanomaterial plasmonic properties, and flow velocity analysis could improve the performance of the VFI. Furthermore, we developed automated image analysis software that shows potential for integrating the diagnostic system into a smartphone. These methods and findings demonstrate that the VFI platform is a highly sensitive device for detecting the LcrV and potentially many other biomarkers.
• Gu, J., Duane, B., Repin, M., Brenner, D. J., & Zenhausern, F. (2021). Transportation container for pre-processing cytogenetic assays in radiation accidents. Scientific reports, 11(1), 10398.
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  We report a shipping container that enables a disruptive logistics for cytogenetic biodosimetry for radiation countermeasures through pre-processing cell culture during transportation. The container showed precise temperature control (
• Chen, P., Gates-Hollingsworth, M., Pandit, S., Park, A., Montgomery, D., AuCoin, D., Gu, J., & Zenhausern, F. (2019). Paper-based Vertical Flow Immunoassay (VFI) for detection of bio-threat pathogens. Talanta, 191, 81-88.
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  Currently, the standard method for identifying biological agents of potential threats to national security and public health, such as pathogens, virus, and toxins, mainly rely on microbiological cultivation. This method is time-consuming and it requires sophisticated equipment and well-trained personnel, which are often unavailable in remote areas or at point-of-need. Therefore, an alternative rapid, simple, and sensitive method for detecting bio-threat agents is in crucial need. We report a paper-based Vertical Flow Immunoassay (VFI) device that can overcome these limitations. The VFI device utilizes a nanoporous nitrocellulose membrane encapsulated in a stainless steel filter holder. As the sample is pushed through the membrane, which is pre-functionalized with capture antibody, a sandwich assay is formed and colorimetric signal is generated to reflect the presence of target antigens. Through theoretical analyses of antigen-antibody binding process inside a porous membrane, we identified two critical factors - membrane pore size and sample flow rate that can be optimized to improve the assay sensitivity. Then, the effects were demonstrated through experimental studies using Burkholderia pseudomallei (the causative agent of melioidosis) as a model pathogen. The B. pseudomallei VFI was based on an immunoassay targeting the B. pseudomallei surface capsular polysaccharide (CPS). The experimental results agreed well with the theory showing that increasing the flow speed (up to 1.06 mm/s) and reducing the membrane pore size (down to 0.1 µm) could improve the sensitivity by at least 5 times. The VFI's limit-of-detection for CPS spiked in buffer solution was determined to be 0.02 ng/mL. The developed VFI shows great potential as a point-of-care tool for detection of bio-threat agents in a variety of clinical and resource-restricted conditions.
• Gu, J., Norquist, A., Brooks, C., Repin, M., Mukherjee, S., Lacombe, J., Yang, J., Brenner, D. J., Amundson, S., & Zenhausern, F. (2019). Development of an integrated fingerstick blood self-collection device for radiation countermeasures. PloS one, 14(10), e0222951.
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  We report the development of system for packaging critical components of the traditional collection kit to make an integrated fingerstick blood collector for self-collecting blood samples of 100 μl or more for radiation countermeasures. A miniaturized vacuum tube system (VacuStor system) has been developed to facilitate liquid reagent storage, simple operation and reduced sample contamination. Vacuum shelf life of the VacuStor tube has been analyzed by the ideal gas law and gas permeation theory, and multiple ways to extend vacuum shelf life beyond one year have been demonstrated, including low temperature storage, Parylene barrier coating and container vacuum bag sealing. Self-collection was also demonstrated by healthy donors without any previous fingerstick collection experience. The collected blood samples showed similar behavior in terms of gene expression and cytogenetic biodosimetry assays comparing to the traditionally collected samples. The integrated collector may alleviate the sample collection bottleneck for radiation countermeasures following a large-scale nuclear event, and may be useful in other applications with its self-collection and liquid reagent sample preprocessing capabilities.
• Wang, H., Barrett, M., Duane, B., Gu, J., & Zenhausern, F. (2018). Materials and processing of polymer-based electrochromic devices. MATERIALS SCIENCE AND ENGINEERING B-ADVANCED FUNCTIONAL SOLID-STATE MATERIALS, 228, 167-174.
• Gu, J., Dong, G., & Zenhausern, F. (2016). Wearable nanotechnology biosensor research and development and its applications in sports. Ti Yu Shi You.
• Brengues, M., Gu, J., & Zenhausern, F. (2015). Microfluidic module for blood cell separation for gene expression radiobiological assays. Radiation protection dosimetry, 166(1-4), 306-10.
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  Advances in molecular techniques have improved discovery of biomarkers associated with radiation exposure. Gene expression techniques have been demonstrated as effective tools for biodosimetry, and different assay platforms with different chemistries are now available. One of the main challenges is to integrate the sample preparation processing of these assays into microfluidic platforms to be fully automated for point-of-care medical countermeasures in the case of a radiological event. Most of these assays follow the same workflow processing that comprises first the collection of blood samples followed by cellular and molecular sample preparation. The sample preparation is based on the specific reagents of the assay system and depends also on the different subsets of cells population and the type of biomarkers of interest. In this article, the authors present a module for isolation of white blood cells from peripheral blood as a prerequisite for automation of gene expression assays on a microfluidic cartridge. For each sample condition, the gene expression platform can be adapted to suit the requirements of the selected assay chemistry.
• Gu, J., & Zenhausern, F. (2014). Experimental characterization of methanol-acetic acid fixative sessile drop dynamics in dry and humid air by video imaging and interference analysis. COLLOIDS AND SURFACES A-PHYSICOCHEMICAL AND ENGINEERING ASPECTS, 449, 141-147.
• Hurth, C., Gu, J., Aboud, M., Estes, M. D., Nordquist, A. R., McCord, B., & Zenhausern, F. (2012). Direct loading of polymer matrices in plastic microchips for rapid DNA analysis: A comparative study. ELECTROPHORESIS, 33(16), 2604-2611.
• Hurth, C., Gu, J., Aboud, M., Estes, M. D., Nordquist, A. R., McCord, B., & Zenhausern, F. (2012). Direct loading of polymer matrices in plastic microchips for rapid DNA analysis: a comparative study. Electrophoresis, 33(16), 2604-11.
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  We report the design and performance validation of microfluidic separation technologies for human identification using a disposable plastic device suitable for integration into an automated rapid DNA analysis system. A fabrication process for a 15-cm long hot-embossed plastic microfluidic devices with a smooth semielliptical cross section out of cyclic olefin copolymer is presented. We propose a mixed polymer solution of 95% w/v hydroxyethylcellulose and 5% w/v polyvinylpyrrolidone for a final polymer concentration of 2.5 or 3.0% to be used as coating and sieving matrix for DNA separation. This formulation allows preparing the microchip without pretreatment in a single-loading step and provides high-resolution separation (≈1.2 bp for fragments
• Zhang, P., Takulapalli, B. R., Morrison, M. E., & Gu, J. (2011). A nanocontact printing system for sub-100 nm aligned patterning.. Nanotechnology, 22(28), 285302. doi:10.1088/0957-4484/22/28/285302
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  Though many aspects of contact printing have been explored extensively since its invention, there are still hurdles to overcome for multilayer printing in the nanometer regime. Here we report on an aligned nanocontact printing (nCP) system that has demonstrated a sub-100 nm alignment capability by means of moiré fringes and microspacers. To address issues in the stamp inking, we have devised a microfluidic apparatus based on the gradient capillary force for transport of ink solutions. The nCP system has been tested by printing nucleoside phosphoramidites on a nanopillar arrayed substrate. Although the nCP system was designed primarily for use in the fabrication of high density DNA nanoarrays, it has the potential to be applied to other fields of nanotechnology for nanoscale patterning.
• Gu, J., Xiao, X., Takulapalli, B. R., Morrison, M. E., Zhang, P., & Zenhausern, F. (2008). A New Approach to Fabricating High-density Nanoarrays by Nanocontact Printing. Journal of vacuum science & technology. B, Microelectronics and nanometer structures : processing, measurement, and phenomena : an official journal of the American Vacuum Society, 26(6), 1860-1865.
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  We introduce a new scheme of nanocontact printing that fabricates nanoarrays using stamps generated by ultraviolet nanoimprint lithography. Array patterns can be generated by this printing technique in a high-density (number of features per unit area) fashion with a feature size as low as 30 nm and period of 100 nm. Sub-500 nm alignment accuracy for multilayer printing has been obtained using a traditional contact mask aligner. We also demonstrate that we can image a nanoarray labeled by streptavidin by atomic force microscope (AFM).
• Gu, J., Xiao, X., Takulapalli, B. R., Morrison, M. E., Zhang, P., & Zenhausern, F. (2008). A new approach to fabricating high density nanoarrays by nanocontact printing. JOURNAL OF VACUUM SCIENCE & TECHNOLOGY B, 26(6), 1860-1865.
• Gu, J., Gupta, R., Chou, C. F., Wei, Q., & Zenhausern, F. (2007). A simple polysilsesquioxane sealing of nanofluidic channels below 10 nm at room temperature. Lab on a chip, 7(9), 1198-201.
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  We present a simple sealing method to fabricate nanofluidic channels, where plasma treated polysilsesquioxane (PSQ) thin film on a rigid support is used to bond to a hydrophilic glass surface permanently at room temperature. This method shows precise dimension control below 10 nm with easy experimental setup. Using this method, one dimensional confined shallow nanochannels with a depth as small as 8 nm and an aspect ratio of
• Yan, H., Mertig, M., Liu, Y., Lin, C., Ke, Y., & Gu, J. (2007). Functional DNA nanotube arrays: bottom-up meets top-down.. Angewandte Chemie (International ed. in English), 46(32), 6089-92. doi:10.1002/anie.200701767
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  Structural DNA nanotechnology[1] has recently opened a new avenue for the fabrication of nanodevices[2] and the massively parallel construction of artificial nanostructures with complex geometry or patterns by DNA self-assembly.[3-5] When functional groups are incorporated into self-assembled DNA nanoarrays they can serve as excellent platforms for the assembly of other species, such as metal nanoparticles,[6-9] antibodies,[10,11] and proteins[12-14] with nanometer precision. Defined large-scale positioning of self-assembled functional DNA nanoarrays on surfaces is also desirable for both fundamental and applied research. Herein we report the fabrication of well-organized arrays of self-assembled functional DNA nanotubes on the sub-millimeter scale by combining the bottom-up and top-down methods. We also demonstrate that such DNA-nanotube arrays can efficiently direct the assembly of arrays of quantum dots, proteins, and DNA targets.
• Gu, J., Zenhausern, F., Wang, J. Z., Sirringhaus, H., & Gu, J. (2006). Low-cost fabrication of submicron all polymer field effect transistors. Applied Physics Letters, 88(13), 133502. doi:10.1063/1.2191088
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  All polymer field effect transistors have been fabricated combining nanoimprint lithography and inkjet printing. Trenches with hydrophilic bottoms confined by hydrophobic walls with considerable height are patterned by nanoimprint lithography. Conducting polymer solutions were then delivered into these trench liquid containers by inkjet printing. Dried conducting polymer in nearby trenches forms source-drain electrodes with the channel length accurately defined by the gap in between the designed two trenches. Top-gate all polymer field effect transistors with submicron channel lengths were successfully realized by such low-cost process.
• Gu, J., Jen, C. P., Wei, Q. H., Chou, C. F., & Zenhausern, F. (2005). Mask fabrication towards sub-10 nm imprint lithography. Emerging Lithographic Technologies IX, Pts 1 and 2, 5751, 382-391.
• Chou, C. F., Gu, J., Wei, Q. H., Liu, Y. J., Gupta, R., Nishio, T., & Zenhausern, F. (2004). Nanopatterned structures for biomolecular analysis towards genomic and proteomic applications. NANOFABRICATION: TECHNOLOGIES, DEVICES AND APPLICATIONS, 5592, 183-192.
• Wei, Q. H., Gu, J., Chou, C. F., & Zenhausern, F. (2004). Integrating nanooptical biosensors into nucleic acid testing devices. EMERGING OPTOELECTRONIC APPLICATIONS, 5363, 45-53.
• Wu, W., Keimel, C. F., Gu, J., Ge, H., & Chou, S. Y. (2003). Room-temperature Si single-electron memory fabricated by nanoimprint lithography. Applied Physics Letters, 83(11), 2268-2270. doi:10.1063/1.1610814
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  We report the design, fabrication, and characterization of room-temperature Si single-electron memories using nanoimprint lithography (NIL). The devices consist of a narrow channel metal–oxide–semiconductor field-effect transistor and a sub-10-nm storage dot, which is located between the channel and the gate. The memories operate at room temperature by charging and discharging one electron in or out of the dot. The charge retention time is up to two days. NIL is shown to be tailored for nanodevice fabrication. By using NIL as a nanolithography tool, the single-electron memory is more feasible for mass production.
• Keimel, C., Gu, J., & Chou, S. Y. (2002). Ultrafast and direct imprint of nanostructures in silicon.. Nature, 417(6891), 835-7. doi:10.1038/nature00792
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  The fabrication of micrometre- and nanometre-scale devices in silicon typically involves lithography and etching. These processes are costly and tend to be either limited in their resolution or slow in their throughput. Recent work has demonstrated the possibility of patterning substrates on the nanometre scale by 'imprinting' or directed self-assembly, although an etching step is still required to generate the final structures. We have devised and here demonstrate a rapid technique for patterning nanostructures in silicon that does not require etching. In our technique which -- we call 'laser-assisted direct imprint' (LADI) -- a single excimer laser pulse melts a thin surface layer of silicon, and a mould is embossed into the resulting liquid layer. A variety of structures with resolution better than 10 nm have been imprinted into silicon using LADI, and the embossing time is less than 250 ns. The high resolution and speed of LADI, which we attribute to molten silicon's low viscosity (one-third that of water), could open up a variety of applications and be extended to other materials and processing techniques.
• Zandbergen, H. W., Yao, N., Gu, J., Farrer, J. K., & Chou, S. Y. (2002). Single-crystal Si formed on amorphous substrate at low temperature by nanopatterning and nickel-induced lateral crystallization. Applied Physics Letters, 81(6), 1104-1106. doi:10.1063/1.1498146
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  Single-crystal silicon has been achieved by patterning amorphous silicon film on silicon dioxide substrate into nanoscale lines and nickel-induced lateral crystallization. Line width affects the single-crystal silicon formation significantly. Narrow line widths, 30 nm or less, resulted in little lateral crystallization; while for line widths above 250 nm, multiple grains started to form. In-situ transmission electron microscope observation has been used to study the crystallization process. Lithography-constrained single seeding is proposed to explain the single-crystal formation.
• Leobandung, E., Guo, L., Gu, J., & Chou, S. Y. (1997). Wire-channel and wrap-around-gate metal–oxide–semiconductor field-effect transistors with a significant reduction of short channel effects. Journal of Vacuum Science & Technology B, 15(6), 2791-2794. doi:10.1116/1.589729
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  Metal–oxide–semiconductor field-effect transistors (MOSFETs) with a wire-channel and wrap-around-gate (WW) structure were fabricated using electron beam lithography and reactive ion etching. The smallest devices have a 35 nm channel width, a 50 nm channel thickness, and a 70 nm channel length. Measurements showed that as the channel width of WW MOSFETs decreased from 75 to 35 nm short channel effects were significantly reduced: the subthreshold slope decreased from 356 to 80 mV/dec and the drain-induced barrier lowering decreased from 988 to 129 mV. Furthermore, the reduction of channel width increases the drive current per unit channel width. A multichannel WW MOSFET with a high current driving capability is discussed.

Proceedings Publications

• Gu, J., Zenhausern, F., Wei, Q., Nishio, T., Liu, Y., Gupta, R., Gu, J., & Chou, C. (2005). Nanopatterned structures for biomolecular analysis toward genomic and proteomic applications. In Nanofabrication: Technologies, Devices, and Applications, 5592, 183-192.
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  We report our fabrication of nanoscale devices using electron beam and nanoimprint lithography (NIL). We focus our study in the emerging fields of NIL, nanophotonics and nanobiotechnology and give a few examples as to how these nanodevices may be applied toward genomic and proteomic applications for molecular analysis. The examples include reverse NIL-fabricated nanofluidic channels for DNA stretching, nanoscale molecular traps constructed from dielectric constrictions for DNA or protein focusing by dielectrophoresis, multi-layer nanoburger and nanoburger multiplets for optimized surface-plasma enhanced Raman scattering for protein detection, and biomolecular motor-based nanosystems. The development of advanced nanopatterning techniques promises reliable and high-throughput manufacturing of nanodevices which could impact significantly on the areas of genomics, proteomics, drug discovery and molecular clinical diagnostics.
• Gu, J., Zenhausern, F., Wei, Q., Gu, J., & Chou, C. (2004). Integrating NanoOptical Biosensors into Nucleic Acid Testing Devices. In Emerging Optoelectronic Applications, 5363, 45-53.
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  Nano optical biosensors employ the interaction between biomolecules and light confined in nanometer scale structures to report the bio-recognition events. This small scale sensing area/volume can ensure that small amount of biorecognition events could be detected. The exceptional sensitivity and high spatial density of nano optical biosensors make them unique in practical applications in nucleic acid detection. Lab-on-a-Chip systems provide the capabilities of separation, cell lysing, polymerase chain reaction (PCR), allowing finishing bio agent detection processes on a chip. In this paper, we present our recent efforts on integrating some novel nanooptical biosensors into Lab-on-a-Chip systems and some preliminary test results.
• Wu, W., Gu, J., & Chou, S. Y. (2002). High performance sub-100 nm Si thin-film transistors by Pattern-controlled crystallization of Thin channel layer and High temperature annealing. In 60th DRC. Conference Digest Device Research Conference, 49-50.
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  In this work, we report the fabrication of high performance thin-film transistors (TFTs) down to sub-100 nm regime using Pattern-controlled crystallization of Thin channel layer and High temperature annealing (PaTH). High temperature is used to improve the film quality. Thin body thickness (Tsi) is used to suppress the short channel effects. The devices showed superior switching properties and device-to-device uniformity over conventional poly-Si TFTs.

Poster Presentations

• Summers, A. J., Devadhasan, J. P., Khanishayan, A., Lacombe, J., Gu, J., & Zenhausern, F. (2023, October). Gold Nanostar-Based Vertical Flow Immunoassay for Detection of Biothreat Agents. BMES Annual Meeting. Seattle, WA.