CONVERSION OF THE LOW QUALITY INDONESIAN NATURALLY-OCCURRING MINERALS INTO SELECTIVE TYPE OF ZEOLITES BY SEED-ASSISTED SYNTHESIS METHOD

An X-ray diffraction (XRD) revealed that Indonesian naturally-occurring mineral from Nanggung, Bogor shows to be a low quality product as it does not seem to contain any zeolite materials. As located in the volcanic area, Indonesia essentially has abundant source of natural zeolites and the country has put much efforts on these treasured materials for export commodity. In order to bring the local natural mineral into high value and to discover whether the mineral has at least zeolitic fragments. we have implemented seed-assisted synthesis to see the possibility of growing zeolite and turn this mineral into high quality. In principle, once the mineral has zeolitic fragment or nuclei, recrystallization of the mineral may occur. By utilizing this mineral as seed in aluminosilicate mother solution, selective mordenite-type (MOR) zeolite can be obtained after hydrothermal treatment. Characterization by XRD showed that this MOR zeolite has high crystallinity and scanning electron microscopy (SEM) depicted the crystal morphology. The natural mineral is conclusively essential for the formation of MOR zeolite by seeding the aluminosilicate mother solution. In the absence of aluminosilicate mother solution, natural mineral can be recrystallized into selective analcime-type (ANA) zeolite. MOR zeolite is known to be useful for several applications such as catalysis whereas ANA zeolite has been considered to be less potential due to relatively small microporosity. Hasil analisis difraksi sinar X (XRD) menunjukkan bahwa mineral alam Indonesia yang berasal dari daerah Nanggung, Bogor memiliki kualitas yang rendah dimana tidak terdapat kandungan material Zeolit. Indonesia yang terletak di kawasan vulkanik memiliki sumber zeolit alam dalam jumlah yang besar dan negara ini telah berusaha untuk menjadikan material ini sebagai komoditi ekspor. Untuk meningkatkan kualitas serta menggali lebih jauh lagi apakah mineral alam ini memiliki setidaknya fragmen atau benih Zeolit, kami telah menerapkan metode sintesis dengan bantuan benih untuk melihat kemungkinan terbentuk atau menumbuhkan material Zeolit dan memberikan mineral ini suatu nilai tambah. Pada prinsipnya, ketika mineral alam memiliki fragmen atau benih Zeolit, rekristalisasi mineral dapat dilakukan. Dengan menggunakan mineral alam sebagai benih Zeolit tipe Mardenit dapat dihasilkan setelah proses hidrotermal. Karakterisasi dengan XRD menunjukkan bahwa zeolit tipe Mordenit yang dihasilkan memiliki kristalinitas yang tinggi, selain itu karakterisasi dengan mikroskopi elektran (SEM) menunjukkan morfologi kristal Zeolit. Hasil ini menunjukkan bahwa keberadaan mineral alam sebagai benih dalam larutan induk aluminosilikat pada metode sintesis penelitian ini, sangat berperan panting dalam pembentukan material Zeolit tipe Mordenit. Sedangkan tanpa adanya larutan induk aluminosilikat, mineral alam tersebut hanya dapat direkristalisasi menjadi material Zeolit tipe Analsim. Material zeolit tipe Mordenit memiliki aplikasi yang lebih leas dan bermanfaat contohnya sebagai katalis, dibandingkan material Zeolit tipe Analsim yang kurang potensial pemanfaatannya karena ukuran mikroporinya yang relatif kecil

Hydroxymethyl PEDOT microstructure-based electrodes for high-performance supercapacitors

The development of conducting polymer-based supercapacitors offers remarkable advantages, such as good ionic and electronic conductivity, ease of synthesis, low processing cost, and mechanical flexibility. 3,4-ethylenedioxythiophene (PEDOT) is a conducting polymer with robust chemical and environmental stability during storage and operation in an aqueous environment. Yet, improving its electrochemical capacitance and cycle life remains a challenge for high-performance supercapacitors exceeding the current state-of-the-art. The fabrication of PEDOT composites with carbon nanomaterials and metal oxides is the commonly used approach to enhance capacitance and stability. This work discusses a comparative study to fabricate highly stable PEDOT derivative electrodes with remarkable specific capacitance via a straightforward electrochemical polymerization technique. The hydroxymethyl PEDOT (PEDOTOH) doped with perchlorate in a dichloromethane (DCM) solvent (197 F g−1) exhibits superior performance compared to the polymer formed in an aqueous solution (124 F g−1). Furthermore, the electropolymerized PEDOTOH on flexible Au/Kapton substrates was assembled into a free-standing symmetrical supercapacitor in an agarose additive-free gel. The use of agarose gel electrolytes can offer easy handling, no leakage, moderate ionic conductivity, and flexibility for miniaturization and integration. The supercapacitor reached a specific capacitance of 36.96 F g−1 at a current density of 13.7 A g−1, an energy density of 14.96 Wh kg−1, and a power density of 22.2 kW kg−1 among the highest values reported for PEDOT-based supercapacitors. The self-standing supercapacitor achieves an industry-par capacitance retention of ∼98% after 10000 charge/discharge cycles at 10 A g−1. This study provides insights into the effect of solvents and electropolymerization modes on the polymer structure and its electrochemical properties toward high-performance supercapacitor devices

Integration of Organic Electrochemical Transistors with Implantable Probes

Funder: King Abdullah University of Science and Technology; Id: http://dx.doi.org/10.13039/501100004052Abstract: Organic electrochemical transistors (OECTs) are widely used as amplifying transducers of biological signals due to their high transconductance and biocompatibility. For implantable applications that penetrate into tissue, OECTs need to be integrated onto narrow probes. The scarcity of real estate necessitates the use of small local gate electrodes and narrow interconnects. This work shows that both of these factors lead to a decrease in the maximum transconductance and an increase in gate voltage required to attain this maximum. This work further shows that coating the gate electrode with a thick conducting polymer improves performance. These findings help guide the development of efficient OECTs on implantable probes

Water stable molecular n-doping produces organic electrochemical transistors with high transconductance and record stability.

From established to emergent technologies, doping plays a crucial role in all semiconducting devices. Doping could, theoretically, be an excellent technique for improving repressively low transconductances in n-type organic electrochemical transistors - critical for advancing logic circuits for bioelectronic and neuromorphic technologies. However, the technical challenge is extreme: n-doped polymers are unstable in electrochemical transistor operating environments, air and water (electrolyte). Here, the first demonstration of doping in electron transporting organic electrochemical transistors is reported. The ammonium salt tetra-n-butylammonium fluoride is simply admixed with the conjugated polymer poly(N,N'-bis(7-glycol)-naphthalene-1,4,5,8-bis(dicarboximide)-co-2,2'-bithiophene-co-N,N'-bis(2-octyldodecyl)-naphthalene-1,4,5,8-bis(dicarboximide), and found to act as a simultaneous molecular dopant and morphology-additive. The combined effects enhance the n-type transconductance with improved channel capacitance and mobility. Furthermore, operational and shelf-life stability measurements showcase the first example of water-stable n-doping in a polymer. Overall, the results set a precedent for doping/additives to impact organic electrochemical transistors as powerfully as they have in other semiconducting devices

アミロイド性タンパク質凝集体検出用電界効果トランジスタ型バイオセンサの開発

早大学位記番号:新7193早稲田大

Ionic-to-electronic coupling efficiency in PEDOT:PSS films operated in aqueous electrolytes

Poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate), PEDOT:PSS, is a polymeric mixed conductor used in the vast majority of devices in bioelectronics, electrochromics, energy storage/generation, neuromorphic computing, and thermoelectrics. These devices operate at the interface with electrolytes and rely on the uptake of mobile ions by the film, making the coupling between electronic and ionic charges crucial. For efficient transduction of ionic charges into electronic ones, all the ions injected into the film should lead to a change in conductivity. Although extensively studied, fundamental knowledge regarding the losses during this process is lacking. In this study, we quantify the efficiency of ion-to-electron coupling in PEDOT:PSS films by measuring the number of cations taken up by the film as well as the in situ current generated as a result of their interactions with the electrically active sites. We find that not all the injected cations are used for reducing PEDOT oligomers in thick films and some of these ions remain in the film upon de-doping. The efficiency of ion-to-electron transduction thus varies with thickness, a parameter which critically affects the distribution of PEDOT and PSS in the bulk as revealed by Raman spectroscopy, X-ray photoelectron spectroscopy and scanning transmission electron microscopy studies. Tracking the traces of ions, we provide guidelines on how to maximize the coupling between ionic and electronic charges for high performance transducers. Our approach is thus fundamental to future development and optimization of mixed conductors applied at the interface with electrolytes

CONVERSION OF THE LOW QUALITY INDONESIAN NATURALLY-OCCURRING MINERALS INTO SELECTIVE TYPE OF ZEOLITES BY SEED-ASSISTED SYNTHESIS METHOD

An X-ray diffraction (XRD) revealed that Indonesian naturally-occurring mineral from Nanggung, Bogor shows to be a low quality product as it does not seem to contain any zeolite materials. As located in the volcanic area, Indonesia essentially has abundant source of natural zeolites and the country has put much efforts on these treasured materials for export commodity. In order to bring the local natural mineral into high value and to discover whether the mineral has at least zeolitic fragments, we have implemented seed-assisted synthesis to see the possibility of growing zeolite and turn this mineral into high quality. In principle, once the mineral has zeolitic fragment or nuclei, recrystallization of the mineral may occur. By utilizing this mineral as seed in aluminosilicate mother solution, selective mordenite-type (MOR) zeolite can be obtained after hydrothermal treatment. Characterization by XRD showed that this MOR zeolite has high crystallinity and scanning electron microscopy (SEM) depicted the crystal morphology. The natural mineral is conclusively essential for the formation of MOR zeolite by seeding the aluminosilicate mother solution. In the absence of aluminosilicate mother solution, natural mineral can be recrystallized into selective analcime-type (ANA) zeolite. MOR zeolite is known to be useful for several applications such as catalysis whereas ANA zeolite has been considered to be less potential due to relatively small microporosity

Enzyme-Free Detection of Glucose with a Hybrid Conductive Gel Electrode

Current assays for glucose monitoring rely predominantly on glucose oxidation-catalyzing enzymes because of the high specificity of enzyme–substrate interactions. Enzymes are however expensive, suffer from instability during fabrication, operation, and storage, and necessitate complex procedures for integration with transducer materials. These challenges, rendering the enzyme-based sensors disadvantageous for routine glucose monitoring, can be overcome by nonenzymatic sensors. Here, for the enzyme-free detection of glucose, an electroactive gel is developed via one-pot polymerization. The functional material is a hybrid of the conducting polymer poly(3,4-ethylenedioxythiophene):polystyrenesulfonate and a polyacrylamide gel functionalized with phenylboronic acid. As an electrode, the gel exhibits a specific current response to glucose within the standard concentration range measured in the complex blood-like medium. When integrated as the lateral, micrometer-scale gate electrode of an organic electrochemical transistor (OECT), the channel current is proven to be sensitive to the presence of glucose in the measurement solution. The advantage of the OECT-based sensor compared to the amperometric electrode is its miniaturized form, amplified input signal as well the elimination of a reference electrode. Adaptable to different geometries, this conducting gel exhibits multifunctionality within its soft, gel-like architecture, that is, mixed ionic and electronic conductivity and glucose-specific electrical response

Effect of human serum on the electrical detection of amyloid-β fibrils in biological environments using azo-dye immobilized field effect transistor (FET) biosensor

As amyloid-β peptide 1–42 (Aβ42) was found to be an emerging and important biomarker for Alzheimer's disease, the detection of this peptide in biological samples such as human serum (HS) has become very important for evaluating the potential disease state and determining the appropriate treatment. In this study, we developed an electrical analysis strategy based on a field effect transistor (FET) biosensor as a simple and reliable technique for confirming the presence of Aβ42 aggregates (fibrils) in biological samples. By utilizing Congo red immobilized on the FET gate surface as a biorecognition element, we observed remarkable sensitivity and specificity for detecting Aβ42 fibrils. Furthermore, we optimized the procedure to minimize the interference of abundant human serum albumin for the detection system using HS samples. The optimized system of Congo red-immobilized FET enables measurement of Aβ42 fibrils in the 100-pM level in HS samples, which is lower than its clinical concentration. The FET device can be applied as a biosensing system for mass and routine screening of peptide biomarkers related to Alzheimer's disease. Keywords: Field effect transistor biosensor, Amyloid beta fibrils, Alzheimer's disease, Human serum albumin, Albumin-amyloid beta complexe