Bio-inspired Passive Skin Cooling for Handheld Microelectronics Devices

Increasing functionality demands more heat dissipation from the skin of handheld microelectronics devices. The maximum amount of heat that can be dissipated passively, prescribed by the natural convection and blackbody radiation theories, is becoming the bottleneck. In this paper, we propose a novel technique that may overcome this passive cooling limit. It is made possible by using a biomimetic skin capable of perspiration on demand. The key component of the biomimetic skin is a thin layer of temperature sensitive hydro gel (TSHG). The TSHG layer can sweat the skin with moisture when the skin temperature is higher than the TSHG’s lower critical solution temperature (LCST), and thus boost the heat dissipation rate through evaporation. The TSHG layer can be refilled by absorbing the moisture in air when the device batteries are being recharged. A generic practice of this novel cooling technique with preliminary analysis and experimental results is presented. With this novel passive cooling technology, a handheld device can be powered 2–4.8 times higher, and may be powerful enough to run a desktop operation system like a personal computer.

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Thickness-Dependent Swelling Behavior of Vapor-Deposited Hydrogel Thin Films

Proceedings ◽

10.3390/proceedings2130757 ◽

2018 ◽

Vol 2 (13) ◽

pp. 757 ◽

Cited By ~ 1

Author(s):

Fabian Muralter ◽

Alberto Perrotta ◽

Anna Maria Coclite

Keyword(s):

Thin Films ◽

Film Thickness ◽

Chemical Vapor ◽

Solution Temperature ◽

Cross Linking ◽

Temperature Sensitive ◽

Critical Solution Temperature ◽

Precise Control ◽

Initiated Chemical Vapor Deposition ◽

Deposited Film

Hydrogel thin films containing temperature sensitive chemical functionalities (such as N-isopropylacrylamide, NIPAAm) are particularly interesting for sensor and actuator setups. Complex 3D structures can be conformally coated by the solvent free technique initiated Chemical Vapor Deposition, with precise control over chemical composition and film thickness. In this study, NIPAAm-based thin films with film thicknesses ranging from tens to several hundreds of nanometers and with different amounts of cross-linking were deposited. Above the lower critical solution temperature (LCST), these films repel out water and hence shrink. The amount of cross-linking and the deposited film thickness were successfully identified to both affect shape and position of the LCST transition of these systems: a promising basis for tuning response properties.

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THERMOSENSITIVE NANOPARTICLES CONJUGATING WITH CD34 ANTIBODY AND ITS SOLUTION PEROPERTIES

Biomedical Engineering Applications Basis and Communications ◽

10.4015/s101623720600035x ◽

2006 ◽

Vol 18 (05) ◽

pp. 222-228 ◽

Cited By ~ 1

Author(s):

CHUN-TE TAO ◽

TAI-HORNG YOUNG

Keyword(s):

Controlled Release ◽

Cloud Point ◽

Lower Critical Solution Temperature ◽

Homogeneous Solution ◽

The Body ◽

Solution Temperature ◽

Temperature Sensitive ◽

Critical Solution Temperature ◽

Human Cd34 ◽

Collapse Temperature

Poly N-isopropylacrylamide (PNIPAAm) is a well-known temperature-sensitive polymer. When the temperature is higher than the lower critical solution temperature (LCST), PNIPAAm aquous solution is cloudy (phase separation occurred). In contrast, when the temperature is lower than the LCST, PNIPAAm is soluble in water (a homogeneous solution). The lower critical solution temperature (LCST) in aqueous solution of PNIPAAm was about 32~33°C. We prepared nano-scaled PNIPAAm particles containing carboxylic group on their surfaces by introducing acrylic acid monomer. The carboxylic groups were applied to conjugate with the amino group of the CD34 antibody. This immuno-conjugate can be applied on targeting the human CD34 positive cells, peripheral blood progenitor cells included, for cell purification and drug controlled release. In order to the active responding of controlled release of the conjugate in the body influenced by temperature, we hope to estimate the shifting of the gel-collapse temperature or cloud point of the immuno-conjugates by dynamic light scattering (DLS) and UV absorption. The results show that the gel-collapse temperature of the nano-particle was not significantly affected by the content of AA between 1.5~5 mol%. However, cloud point of the solution was elevated by the conjugation of CD34 antibody to 37°C. When CD34-conjugated particle was subsequently incorporated with recombinant FLT3-ligand, which is a smaller molecule compare to CD34 antibody, cloud point of the solution was not affected.

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Key Factors to Prepare Polyelectrolytes Showing Temperature-Sensitive Lower Critical Solution Temperature-type Phase Transitions in Water

Australian Journal of Chemistry ◽

10.1071/ch11378 ◽

2012 ◽

Vol 65 (1) ◽

pp. 91 ◽

Cited By ~ 63

Author(s):

Yuki Kohno ◽

Hiroyuki Ohno

Keyword(s):

Phase Transition ◽

Lower Critical Solution Temperature ◽

Alkyl Chain ◽

Alkyl Chain Length ◽

Phase Behaviour ◽

Solution Temperature ◽

Temperature Sensitive ◽

Key Factors ◽

Critical Solution Temperature ◽

Type Phase

Tetrabutylphosphonium styrenesulfonate and its homopolymer showed a lower critical solution temperature-type phase transition in water. As the hydrophobicity of these monomeric and polymeric salts affects phase behaviour, the phase transition temperature of the polyelectrolyte was changed by the introduction of monomers having different alkyl chain length on the phosphonium cations.

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Study on the Effect of 1-Butanol Soluble Lignin on Temperature-Sensitive Gel

Polymers ◽

10.3390/polym10101109 ◽

2018 ◽

Vol 10 (10) ◽

pp. 1109 ◽

Cited By ~ 5

Author(s):

Pan Jiang ◽

Yi Cheng ◽

Sheng Yu ◽

Jie Lu ◽

Haisong Wang

Keyword(s):

Environmental Temperature ◽

Hydroxyl Group ◽

Solution Temperature ◽

Temperature Sensitive ◽

Stimuli Responsive ◽

Agricultural Field ◽

Absorption Properties ◽

Critical Solution Temperature ◽

Temperature Sensitive Hydrogel ◽

Soluble Lignin

A protocol for the fractionation of lignin with 1-butanol as solvent has been proposed in order to improve the utilization of industry alkali lignin. 1-butanol soluble lignin (BSL) was used as a building block for temperature-sensitive hydrogel with N-isopropylacrylamide (NIPAAm) through graft polymerization. The result shows that 1-butanol fractionation is an effective method to improve the molecular weight homogeneity of lignin (PDI, 2.5 to 1.83) and increase the hydroxyl group content (0.585–1.793 mmol/g). The incorporation of BSL into the temperature-sensitive hydrogel can enhance the thermal stability and increase the hydrophobicity of the gel, which leads to a decrease in lower critical solution temperature (LCST). In addition, the compression strength, swelling ratio, and pore size of the gel can be adjusted by the dosage of lignin. This stimuli-responsive gel, with an LCST around 32 °C, is expected to be applied in the agricultural field as a pesticide carrier by stimulating release and absorption properties based on the change in natural environmental temperature.

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Novel Thermosensitive Core–Shell Surface Molecularly Imprinted Polymers Based on SiO2 for the Selective Adsorption of Sulfamethazine

Materials ◽

10.3390/ma11112067 ◽

2018 ◽

Vol 11 (11) ◽

pp. 2067 ◽

Cited By ~ 1

Author(s):

Weihong Huang ◽

Yujie Qing ◽

Ningwei Wang ◽

Yi Lu ◽

Tianshu Liu ◽

...

Keyword(s):

Selective Adsorption ◽

Solution Temperature ◽

Core Shell ◽

Temperature Sensitive ◽

Critical Solution Temperature ◽

Molecularly Imprinted ◽

Surface Polymerization ◽

Adsorption Temperature ◽

Polymerization Method ◽

Experimental Group

In this research, a novel, sulfamethazine, thermosensitive, molecularly-imprinted polymer (MIP) with an obvious core–shell structure for the enrichment of sulfamethazine (SMZ), which involved temperature sensitive monomer N-Isopropylacrylamide, functional monomer methacrylic acid and cross-linking agents ethyleneglycol dimethacrylate (EGDMA) and N,N′-methylenebisacrylamide, was successfully compounded using the surface polymerization method. To ensure the best experimental group, we designed and compared three groups of controlled experiments of MIPs with different crosslinking agents. When the adsorption temperature was almost the lower critical solution temperature (LCST) of Poly(N-Isopropylacrylamide), the preparative MIPs showed outstanding adsorption capacity and specific identification to sulfamethazine. Moreover, this allowed the MIPs to better facilitate by combining the template molecules, as well as optimizing the imprinting factor. In addition, after 80 min, the adsorption of the MIPs leveled off and remained constant, and the adsorption quantity reached (a maximum of) at 8.1 mg·g−1.

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Microfluidics of Binary Liquid Mixtures with Temperature-Dependent Miscibility

10.26434/chemrxiv.6970301 ◽

2019 ◽

Author(s):

Maximiliano J. Fornerod ◽

Esther Amstad ◽

Stefan Guldin

Keyword(s):

Phase Separation ◽

Flow Regimes ◽

Liquid Mixtures ◽

Binary Liquid Mixtures ◽

Solution Temperature ◽

Microfluidic Channels ◽

Temperature Sensitive ◽

Critical Solution Temperature ◽

Binary Liquid ◽

Sensing Applications

Liquid-liquid microfluidic systems rely on the intricate control over the fluid properties of either miscible or immiscible mixtures. Herein, we report on the use of partially miscible binary liquid mixtures that lend their microfluidic properties from a highly temperature-sensitive mixing and phase separation behaviour. For a blend composed of the thermotropic liquid crystal 4-Cyano-4'-pentylbiphenyl (5CB) and methanol, mixing at temperatures above the upper critical solution temperature (UCST; 24.4°C) leads to a uniform single phase while partial mixing can be achieved at temperatures below the UCST. Thermally-driven phase separation inside the microfluidic channels results in the spontaneous formation of very regular phase arrangements, namely in droplets, plug, slug and annular flow. We map different flow regimes and relate findings to the role of interfacial tension and viscosity and their temperature dependence. Importantly, different flow regimes can be achieved at constant channel architecture and flow rate by varying the temperature of the blend. A consistent behaviour is observed for a binary liquid mixture with lower critical solution temperature, namely 2,6-lutidine and water. This temperature-responsive approach to microfluidics is an interesting candidate for multi-stage processes, selective extraction and sensing applications.

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Microfluidics of Binary Liquid Mixtures with Temperature-Dependent Miscibility

10.26434/chemrxiv.6970301.v2 ◽

2019 ◽

Author(s):

Maximiliano J. Fornerod ◽

Esther Amstad ◽

Stefan Guldin

Keyword(s):

Phase Separation ◽

Flow Regimes ◽

Liquid Mixtures ◽

Binary Liquid Mixtures ◽

Solution Temperature ◽

Microfluidic Channels ◽

Temperature Sensitive ◽

Critical Solution Temperature ◽

Binary Liquid ◽

Sensing Applications

Liquid-liquid microfluidic systems rely on the intricate control over the fluid properties of either miscible or immiscible mixtures. Herein, we report on the use of partially miscible binary liquid mixtures that lend their microfluidic properties from a highly temperature-sensitive mixing and phase separation behaviour. For a blend composed of the thermotropic liquid crystal 4-Cyano-4'-pentylbiphenyl (5CB) and methanol, mixing at temperatures above the upper critical solution temperature (UCST; 24.4°C) leads to a uniform single phase while partial mixing can be achieved at temperatures below the UCST. Thermally-driven phase separation inside the microfluidic channels results in the spontaneous formation of very regular phase arrangements, namely in droplets, plug, slug and annular flow. We map different flow regimes and relate findings to the role of interfacial tension and viscosity and their temperature dependence. Importantly, different flow regimes can be achieved at constant channel architecture and flow rate by varying the temperature of the blend. A consistent behaviour is observed for a binary liquid mixture with lower critical solution temperature, namely 2,6-lutidine and water. This temperature-responsive approach to microfluidics is an interesting candidate for multi-stage processes, selective extraction and sensing applications.

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Fabrication of Thermoresponsive Glycopolymers Fibers for Lectin Recognition

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.821-822.981 ◽

2013 ◽

Vol 821-822 ◽

pp. 981-985

Author(s):

Lei Wang ◽

Jing Quan ◽

Li Min Zhu

Keyword(s):

Intelligent Control ◽

Glucose Solution ◽

Polymerization Process ◽

Solution Temperature ◽

Temperature Sensitive ◽

Con A ◽

Critical Solution Temperature ◽

H Nmr ◽

Lectin Recognition ◽

Scanning Electron

A thermoresponsive glycopolymer poly-(N-isopropylacrylamide-co-6-O-vinylsebacoyl D-glucose) (poly-NIPAM-co-VSEG; PNE) has been prepared by free radical polymerization process, and subsequently processed into nanofibers with poly-L-lactide-co-ε-caprolactone (PLCL) using electrospinning. The thermoresponsive glycopolymer materials have been characterized by Fourier transform infrared (FTIR) spectroscopy, 1H NMR, and scanning electron microscopy (SEM). And the lower critical solution temperature (LCST) of these thermoresponsive materials was also measured. The nanofibers containing PNE can greatly selective recognize with lectin Concanavalin A (Con A), and the adsorbed Con A can be easily eluted by 1 M glucose solution. These results indicate that PNE can separate and purify proteins, and also the temperature sensitive characteristic has the potential to achieve the intelligent control.

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Conformational Stability of Poly (N-Isopropylacrylamide) Anchored on the Surface of Gold Nanoparticles

Materials ◽

10.3390/ma14020443 ◽

2021 ◽

Vol 14 (2) ◽

pp. 443

Author(s):

Runmei Li ◽

Cong Cheng ◽

Zhuorui Wang ◽

Xuefan Gu ◽

Caixia Zhang ◽

...

Keyword(s):

Gold Nanoparticles ◽

Temperature Sensitivity ◽

Electrostatic Interaction ◽

Strong Interaction ◽

Lower Critical Solution Temperature ◽

Conformational Stability ◽

Solution Temperature ◽

Temperature Sensitive ◽

Critical Solution Temperature ◽

Temperature Variations

To verify the temperature sensitive failure of poly (N-isopropylacrylamide) (PNIPAM) anchored on the surface of gold nanoparticles (AuNPs), the UV-Vis spectra with temperature variations of the following aqueous solutions respectively containing AuNPs-PNIPAM, Au-PNIPAM/PNIPAM, PNIPAM, in different media (including salt, ethanol, HCl and cetyltrimethylammoniumbromide (CTAB)), were systematically determined. The results indicated that the UV-Vis spectrum of AuNPs-PNIPAM suspension hardly changed even above the Lower Critical Solution Temperature (LCST) of PNIPAM, but that of Au-PNIPAM/PNIPAM sharply increased only in absorbance intensity. A possible mechanism of the failed temperature sensitivity of PNIPAM anchored on the surface of AuNPs was proposed. Being different from free PNIPAM molecules, a strong interaction exists among PNIPAM molecules anchored on the surface of AuNPs, restraining the change in conformation of PNIPAM. The temperature sensitivity of Au-PNIPAM/PNIPAM originates from the free PNIPAM molecules rather than the anchored PNIPAM one. The changing electrostatic interaction could effectively regulate the aggregation behavior of AuNPs-PNIPAM and enhance its sensitivity to temperature.

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