Showing papers by "Tingrui Pan published in 2017"

Supercapacitive iontronic nanofabric sensing

Abstract: The study of wearable devices has become a popular research topic recently, where high-sensitivity, noise proof sensing mechanisms with long-term wearability play critical roles in a real-world implementation, while the existing mechanical sensing technologies (i.e., resistive, capacitive, or piezoelectric) have yet offered a satisfactory solution to address them all. Here, we successfully introduced a flexible supercapacitive sensing modality to all-fabric materials for wearable pressure and force sensing using an elastic ionic-electronic interface. Notably, an electrospun ionic fabric utilizing nanofibrous structures offers an extraordinarily high pressure-to-capacitance sensitivity (114 nF kPa-1 ), which is at least 1000 times higher than any existing capacitive sensors and one order of magnitude higher than the previously reported ionic devices, with a pressure resolution of 2.4 Pa, achieving high levels of noise immunity and signal stability for wearable applications. In addition, its fabrication process is fully compatible with existing industrial manufacturing and can lead to cost-effective production for its utility in emerging wearable uses in a foreseeable future.

Photopatternable PEDOT:PSS/PEG hybrid thin film with moisture stability and sensitivity.

Abstract: A wearable humidity sensor that can analyse perspiration and breath rates has been devised by researchers in the United States. A conductive polymer known as poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) has been deployed with success in flexible electronic devices, but it can degrade when exposed to water or photolithography solvents. To mitigate these problems, Tingrui Pan from the University of California, Davis, and his colleagues coated PEDOT:PSS onto poly (ethylene glycol), a pliable substrate that is able to absorb water. They then developed a process that connects a photomask to the conductive polymer and patterns it in a single step, using ultraviolet light and a photosensitive cross-linking reagent. This strategy produced hybrid films in a capacitive sensing mode that show capacitive signals change with rising environmental moisture and that are resilient enough for real-time exercise monitoring.

Wearable microfluidics: fabric-based digital droplet flowmetry for perspiration analysis

Abstract: The latest development in wearable technologies has attracted much attention. In particular, collection and analysis of body fluids has been a focus. In this paper, we have reported a wearable microfluidic platform made using conventional fabric materials and laser micromachining to measure the flow rate on a patterned fabric surface, referred to as digital droplet flowmetry (DDF). The proposed wearable DDF is capable of collecting and measuring continuous perspiration with high precision (96% on average) in a real-time fashion over a defined area of skin. We have introduced a theoretical model for the proposed wearable interfacial microfluidic platform, under which various design parameters have been investigated and optimized for various conditions. The novel digitalized measurement principle of DDF provides fast responses, digital readouts, system flexibility, and continuous performance of the flow measurement. Moreover, the proposed DDF platform can be conveniently implemented on regular apparel or a wearable device, and has potential to be applied to dynamic removal, collection and monitoring of biofluids for various physiological and clinical processes.

Collective cell migration has distinct directionality and speed dynamics

Abstract: When a constraint is removed, confluent cells migrate directionally into the available space. How the migration directionality and speed increase are initiated at the leading edge and propagate into neighboring cells are not well understood. Using a quantitative visualization technique-Particle Image Velocimetry (PIV)-we revealed that migration directionality and speed had strikingly different dynamics. Migration directionality increases as a wave propagating from the leading edge into the cell sheet, while the increase in cell migration speed is maintained only at the leading edge. The overall directionality steadily increases with time as cells migrate into the cell-free space, but migration speed remains largely the same. A particle-based compass (PBC) model suggests cellular interplay (which depends on cell-cell distance) and migration speed are sufficient to capture the dynamics of migration directionality revealed experimentally. Extracellular Ca2+ regulated both migration speed and directionality, but in a significantly different way, suggested by the correlation between directionality and speed only in some dynamic ranges. Our experimental and modeling results reveal distinct directionality and speed dynamics in collective migration, and these factors can be regulated by extracellular Ca2+ through cellular interplay. Quantitative visualization using PIV and our PBC model thus provide a powerful approach to dissect the mechanisms of collective cell migration.

Multi-dimensional studies of synthetic genetic promoters enabled by microfluidic impact printing

Abstract: Natural genetic promoters are regulated by multiple cis and trans regulatory factors For quantitative studies of these promoters, the concentration of only a single factor is typically varied to obtain the dose response or transfer function of the promoters with respect to the factor Such design of experiments has limited our ability to understand quantitative, combinatorial interactions between multiple regulatory factors at promoters This limitation is primarily due to the intractable number of experimental combinations that arise from multifactorial design of experiments To overcome this major limitation, we integrate impact printing and cell-free systems to enable multi-dimensional studies of genetic promoters We first present a gradient printing system which comprises parallel piezoelectric cantilever beams as a scalable actuator array to generate droplets with tunable volumes in the range of 100 pL–10 nL, which facilitates highly accurate direct dilutions in the range of 1–10 000-fold in a 1 μL drop Next, we apply this technology to study interactions between three regulatory factors at a synthetic genetic promoter Finally, a mathematical model of gene regulatory modules is established using the multi-parametric and multi-dimensional data Our work creates a new frontier in the use of cell-free systems and droplet printing for multi-dimensional studies of synthetic genetic constructs

The Typical Metabolic Modifiers Conferring Improvement in Cancer Resistance.

Abstract: Background: Cancer metabolic reprogramming rekindles enthusiasm for the research of metabolic regulation in cancer drug resistance. A growing number of metabolic modifiers combined with cancer drugs obtain the expected efficacy in in vitro or in vivo studies, also in clinical trial studies, indicating a good potential of enhancing efficacy and reducing resistance. Hence, a comprehensive review on the attenuations of metabolic modifiers in cancer drug resistance is necessary for rational drug design and clinical cancer drug research. Methods: Cancer drug resistance and cancer metabolic reprogramming were used as the key words to collect publications with reference value in bibliographic databases. Specifically, the focused question is the advances of metabolic modifiers on cancer resistance improvement. Figures and tables were applied to analyze the interventions in accordance with inclusion criteria. Results: This review summarized the advances of metabolic modifiers combined with cancer drugs in in vitro, in vivo and clinical trial studies, especially for cancer resistance improvement. The relationship between metabolic regulation and cancer resistance was elaborated, and the potential metabolic modifiers were embraced. Metabolic targets were also visualized in categorization in 4 figures and expatiated in 4 tables. Three typical metabolic modifiers, namely lonidamine, 2-DG and 3-BrPA, conferring attenuation to cancer resistance were elucidated systematically. Conclusion: Metabolic regulation is an intervention with targeted perturbation in a modest manner and reflects homeostasis balance. When combined with cancer drugs, the metabolic modifiers always show an exciting potential with practical significance, enhancing activity or exerting synergism. Highlights: • The metabolic modifiers confer attenuation in cancer resistance. • The cross talk between cancer resistance and reprogramming metabolism are discussed. • A number of metabolic modifiers combined with cancer drugs are summarized. Key words: Cancer Resistance; Cancer Metabolic Reprogramming; Metabolic Modifiers; Lonidamine; 2-deoxy-D-glucose; 3-bromopyruvate

Electrospun nanofabric based all-fabric iontronic pressure sensor

Abstract: The study of wearable devices has become a popular research topic recently, where high-sensitivity, noise proof sensing mechanisms with long-term wearability play critical roles in a real-world implementation. Here, we introduced a flexible supercapacitive sensing modality to all-fabric materials for wearable pressure and force sensing using an elastic ionic-electronic interface. Notably, an electrospun ionic fabric utilizing nanofibrous structures offers an extraordinarily high pressure-to-capacitance sensitivity (114 nF·kPa−1), which is at least 1,000 times higher than any existing capacitive sensors and one order of magnitude higher than the previously reported ionic devices, with a pressure resolution of 2.4 Pa, achieving high levels of noise immunity and signal stability for wearable applications.

Wearable emotional feedback apparatus for autism spectrum disorder

Abstract: A wearable emotional feedback apparatus "AutiSense", for collecting and displaying emotional feedback information for use in working with those having Autism Spectrum Disorder (ASD). A wearable sensing mesh (e.g., glove or sock) is configured with physiological sensors, including skin response and heart rate, for detecting response to emotional stimuli and communicating the information to a mobile device for display and optional storage and additional processing.

Polymeric devices and methods of making

Abstract: Some polymeric devices, as described herein, can be made of a first layer and a second layer bonded together with one or more microfluidic channels defined internal to the device. The first layer and the second layer may each include a substrate and a polymer bonded to the substrate. The two layers may be bonded through a polymer network that interpenetrates the polymers in the first and second layers. This disclosure also describes methods of bonding together polymeric articles. The methods include diffusing polymerizable monomers and radical forming initiators into the surfaces of one or both of the polymers, putting the surfaces into contact, and initiating polymerization to create a polymer network that interpenetrates the polymers.

Microfluidic print-to-synthesis enabled combinatorial peptide microarray for cancer targeting

Abstract: This paper reports our newly developed microfluidic print-to-screen (MPS) platform and its application for synthesizing combinatorial peptide on PEG microdisc array. The MPS platform possesses several distinct features including easy operation, free of contamination, multiplexibility, low cost, high throughput and array density. The performance of the MPS system is characterized and, as proof of concept, a tetrapeptide library was constructed with an array density of 2560 spots/slide using the MPS approach. The library was screened for ligands targeting α4β1 integrin overexpressed on tumor cell plasma membranes. Repeatable outcomes demonstrate the feasibility of the MPS platform, as well as identification of positive sequences that actively bind to tumor cells.

Photopatternable and moisture-stable PEDOT:PSS/PEG hybrid thin-film for flexible and wearable humidity sensing

Abstract: Degradation and delamination have been technically challenging for poly(3,4-ethylenedioxythiophene): polystyrene sulfonate) (PEDOT:PSS) thin-film processing due to environmental humidity. To overcome this problem, we introduced a one-step photolithographic method to both pattern and link a PEDOT:PSS film onto a PEG layer as a hybrid thin-film structure on a flexible substrate, which exhibited excellent long-term moisture stability (10 days) and high lithographic resolution (2 urn). Mechanical characterizations (bending and tensile tests) illustrated strong adhesions between the PEDOT:PSS and PEG layers as well as between the hybrid thin-film and substrate. Moreover, the hybrid moisture-absorbable film showed a quick response of its permittivity to environmental humidity variations, in which patterned PEDOT:PSS layer served as an electrode and the PEG layer as a moisture sensing element. As demonstrations, perspiration tracking over various parts of the body surface as well as breath rate measurement were successfully carried out, which illustrated the potential utility of this stable hybrid thin-film for emerging flexible and wearable humidity sensing applications.