Seon‐Jin Choi

Sensitive detection of acetone and hydrogen sulfide levels in exhaled human breath, serving as breath markers for some diseases such as diabetes and halitosis, may offer useful information for early diagnosis of these diseases. Exhaled breath analyzers using semiconductor metal oxide (SMO) gas sensors have attracted much attention because they offer low cost fabrication, miniaturization, and integration into portable devices for noninvasive medical diagnosis. However, SMO gas sensors often displ

Thin-walled WO(3) hemitubes and catalytic Pt-functionalized WO(3) hemitubes were synthesized via a polymeric fiber-templating route and used as exhaled breath sensing layers for potential diagnosis of halitosis and diabetes through the detection of H(2)S and CH(3)COCH(3), respectively. Pt-functionalized WO(3) hemitubes with wall thickness of 60 nm exhibited superior acetone sensitivity (R(air)/R(gas) = 4.11 at 2 ppm) with negligible H(2)S response, and pristine WO(3) hemitubes showed a 4.90-fold

Diagnostic sensing device using exhaled breath of human have critical advantages due to the noninvasive diagnosis and high potential for portable device with simple analysis process. Here, we report ultrafast as well as highly sensitive bumpy WO3 hemitube nanostructure assisted by O2 plasma surface modification with functionalization of graphene-based material for the detection of acetone (CH3COCH3) and hydrogen sulfide (H2S) which are biomarkers for the diagnosis of diabetes and halitosis, resp

Macroporous WO3 nanotubes (NTs) functionalized with nanoscale catalysts were fabricated using coaxial electrospinning combined with sacrificial templating and protein-encapsulated catalysts. The macroporous thin-walled nanotubular structures were obtained by introducing colloidal polystyrene (PS) particles to a shell solution of W precursor and poly(vinylpyrrolidone). After coaxial electrospinning with a core liquid of mineral oil and subsequent calcination, open pores with an average diameter o

Abstract Humidity sensors are essential components in wearable electronics for monitoring of environmental condition and physical state. In this work, a unique humidity sensing layer composed of nitrogen‐doped reduced graphene oxide ( n RGO) fiber on colorless polyimide film is proposed. Ultralong graphene oxide (GO) fibers are synthesized by solution assembly of large GO sheets assisted by lyotropic liquid crystal behavior. Chemical modification by nitrogen‐doping is carried out under thermal a

Optically reduced graphene oxide (RGO) sheets were produced on a thermally stable and highly transparent colorless polyimide (CPI) substrate by irradiating intense pulsed light (IPL) on a GO-coated CPI film. These RGO sheets can be used as flexible gas sensing layers for wearable applications. Ultrafast IPL irradiation formed RGO sheets on the CPI film within 4 msec without any damage on the plastic substrate. The IPL-induced RGO (IPL-RGO) sheets exhibited dramatically improved chemical sensing

A novel catalyst functionalization method, based on protein-encapsulated metallic nanoparticles (NPs) and their self-assembly on polystyrene (PS) colloid templates, is used to form catalyst-loaded porous WO3 nanofibers (NFs). The metallic NPs, composed of Au, Pd, or Pt, are encapsulated within a protein cage, i.e., apoferritin, to form unagglomerated monodispersed particles with diameters of less than 5 nm. The catalytic NPs maintain their nanoscale size, even following high-temperature heat-tre

Tailoring of semiconducting metal oxide nanostructures, which possess controlled pore size and concentration, is of great value to accurately detect various volatile organic compounds in exhaled breath, which act as potential biomarkers for many health conditions. In this work, we have developed a very simple and robust route for controlling both the size and distribution of spherical pores in electrospun WO3 nanofibers (NFs) via a sacrificial templating route using polystyrene colloids with dif

We propose a new route for transferring catalysts onto macroporous metal oxide nanofibers (NFs) using metallic nanoparticles (NPs) infiltrated block copolymer microparticles as sacrificial templates. Pt decorated polystyrene- b -poly(4-vinylpyridine) (PS- b -P4VP) copolymer microparticles (Pt-BCP MPs), produced from oil-in-water emulsions, were uniformly dispersed within electrospun PVP/W precursor composite NFs. The macropore-loaded WO 3 NFs (macroporous Pt-WO 3 NFs), which are additionally fun

, was investigated. This work demonstrates that optimized co-sensitization of two catalysts (i.e., Ir NPs and GO sheets) on p-type metal oxide NFs enables the precise detection of exhaled breath gases for the diagnosis of diabetes.

Optically reduced graphene oxide (ORGO) sheets are successfully integrated on silver nanowire (Ag NW)‐embedded transparent and flexible substrate. As a heating element, Ag NWs are embedded in a colorless polyimide (CPI) film by covering Ag NW networks using polyamic acid and subsequent imidization. Graphene oxide dispersed aqueous solution is drop‐coated on the Ag NW‐embedded CPI (Ag NW‐CPI) film and directly irradiated by intense pulsed light to obtain ORGO sheets. The heat generation property

Hollow SnO2 spheres functionalized by Au catalysts were synthesized via the use of Au-decorated block copolymer (Au-BCP) sphere templates. Uniformly distributed Au nanoparticles on BCP spheres were prepared by the infiltration of Au precursors into polystyrene-b-poly(4-vinylpyridine) (PS-b-P4VP) spheres. A thin SnO2 layer was coated on the Au-BCP spheres using RF sputtering at room temperature without morphological deformation of the spheres. The Au nanoparticles were uniformly transferred from

2D Ru oxide nanosheets (NSs) with optically punched nanoholes are synthesized and integrated on a flexible heating substrate, i.e., silver nanowire (Ag NW)‐embedded colorless polyimide (cPI) film, for application in wearable chemical sensors. Multiple discrete pores on the sub‐5‐nm scale are formed on the basal planes of Ru oxide NSs by irradiation of intense pulsed light. The chemical sensing characteristic of the porous Ru oxide NSs toward nitrogen dioxide (NO 2 ) is investigated under control