Wearable Battery-Free Perspiration Analyzing Sites Based on Sweat Flowing on ZnO Nanoarrays

We fabricated wearable perspiration analyzing sites for actively monitoring physiological status during exercises without any batteries or other power supply.The device mainly consists of ZnO nanowire(NW)arrays and flexible polydimethylsiloxane substrate.Sweat on the skin can flow into the flow channels of the device through capillary action and flow along the channels to ZnO NWs.The sweat flowing on the NWs(with lactate oxidase modification)can output a DC electrical signal,and the outputting voltage is dependent on the lactate concentration in the sweat as the biosensing signal.ZnO NWs generate electric double layer(EDL)in sweat,which causes a potential difference between the upper and lower ends(hydrovoltaic effect).The product of the enzymatic reaction can adjust the EDL and influence the output.This device can be integrated with wireless transmitter and may have potential application in constructing sports big data.This work promotes the development of next generation of biosensors and expands the scope of self-powered physiological monitoring system.

Impact of Artificial Perspiration on Photo-stability of Reactive Dyes on Cellulose

The photo-reactions between metabolic products of human sweat and dyestuffs on garments may produce many toxic substances which could directly contact skin and threaten human health. In order to investigate the impact of the perspiration on photo-fading of reactive dyes on cellulose, nine commercial reactive dyes belonging to three types of chromophores (azo, Cu-complex azo and anthraquinone) respectively were chosen and their perspiration-light stability on cotton fabric was studied following ATTS test standard. It is found that the impact of the artificial perspiration on dyes varies with different chromophores: anthraquinone reactive dyes always show the best photo-stability, whereas Cu-complex azo reactive dyes appear to be the most sensitive under exposure to light and perspiration. The pH value of perspiration also greatly influences the fading of dyes with different reactive groups: the fading rate of most chlorotriazinyl reactive dyes in acidic perspiration (pH=3.5) is higher than in alkaline perspiration (pH=8.0), while the reverse is true for most vinylsulphonyl dyes. Furthermore, the study of the contribution of individual component of the artificial perspiration discloses that L-Histidine monohydrochloride monohydrate, DL-Aspartic acid and lactic acid play the major roles on the photo-fading of those selected dyestuffs and inorganic salts including disodium hydrogen phosphate and sodium chloride usually decelerate photo-fading.

Degradation research of protective coating on AZ91D Mg alloy components via simulated contamination

Accelerated environmental(hygrothermal)exposure experiments are performed on organic paints coated on commercial die-cast AZ91D Mg alloys to investigate the effects of contamination on blistering.Specifically,artificial human perspiration spray is used to contaminate the substrate surface.Blistering occurred only for paints that are spread on surfaces with the perspiration present.More blisters gradually form at longer test times,and the volume of blistering increases.Scanning electron microscopy indicates that blistering is initiated by contamination and/or substrate corrosion at the interface of the organic paints and the substrate.Blistering is characterized for two samples exposed to the hygrothermal environments for various times,and is found to be initially empty in the early stages.Hydrophilic chloride contaminants from the perspiration lead to in situ adhesion loss.Simultaneously,the paints volume expands,and the associated compressive stress causes it to bulge.After long-term test exposure,chloride anions corrode the substrate under the films,and MgO,Mg(OH)_(2),and Mg_(2)(OH)_(3)Cl corrosion products fill the blisters.Finally,a model of blistering evolution is discussed.

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

Degradation and delamination resulting from environmental humidity have been technically challenging for poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate)(PEDOT:PSS)thin-film processing.To overcome this problem,we introduced a one-step photolithographic method to both pattern and link a PEDOT:PSS film onto a poly(ethylene glycol)(PEG)layer as a hybrid thin film structure on a flexible substrate.This film exhibited excellent long-term moisture stability(more than 10 days)and lithographic resolution(as low as 2μm).Mechanical characterizations were performed,including both stretching and bending tests,which illustrated the strong adhesion present 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 the patterned PEDOT:PSS layer served as an electrode and the PEG layer as a moisture-sensing element.Perspiration tracking over various parts of the body surface as well as breath rate measurement under the nose were successfully carried out as demonstrations,which illustrated the potential utility of this stable hybrid thin film for emerging flexible and wearable electronic applications.