Cobalt oxides/hydroxides have attracted increasing attention in the electrocatalytic oxidation reaction of 5-hydroxymethylfufural (HMFOR) at ambient conditions for 2,5-furandicarboxylic acid (FDCA) production recently, but the understanding of the interplay of...
An iridium oxide-based electrical pH sensor that is suitable to be embedded in an electronic bandage for skin monitoring has been developed. The electrical pH sensor does not entail high-temperature fabrication processes thus is suitable to be built on polypropylene micro membrane (PPMM), a paperlike substrate, which is inert, gas-permeable, and biomechanically-compatible to tissue. The PPMM was metalized by an electroless gold-coating process and iridium oxide nanoparticles were electrodeposited on the porous membranes. The reference electrode was made by screen printing Ag/AgCl paste on the substrate. pH responses of the IrO 2 PPMM against a commercial reference electrode or the planar Ag/AgCl reference electrode were examined. A super-Nernstian sensitivity of −66.8 mV/pH was achieved with the PPMMbased sensor in a pH range from pH 2 to 13. The electrodes also produced similar responses in smaller pH ranges of pH 5 to 8 and around pH 7. Output potential characterization, such as cyclic voltammetry, hysteresis, response time, potential drift, deviation, fluctuation, and potential stability, showed repeatable and stable pH responses in physiologically relevant pH ranges. Interference factors such as salt concentration, viscosity and temperature have also been investigated. The results show that the calibration procedures should consider these factors specific to targeted applications. The planar pH-sensitive electrodes show reliable performance in a bandage configuration designed and packaged for wound monitoring. The accuracy assessment in a Clarke error grid and the result of sensing pH induced by uric acid showed the feasibility of bandage applications. The electrical and biocompatible electrodes embedded in breathable porous bandages can be integrated with portable electronics to be used as wearables for wireless tissue monitoring.INDEX TERMS pH sensor, planar, iridium oxide, polypropylene micro membrane, electronic bandage.
Chitosan is considered to be a natural polymer for promising applications in drug delivery, wound dressing/healing, biocompatible coating, and tissue engineering. Since the chitosan is known for bio-compatibility, non-toxicity, anti-bacterial ability, and low cost, there has been increasing interest to leverage the unique characteristics of chitosan to fabricate bio-composites for specific bio-medical purposes. In this work, we demonstrate a facile synthetic approach to fabricate composite hydrogels consisting of chitosan, poly(3,4-ethylenedioxythiophene (PEDOT), and iridium oxide (IrO2) nanoparticles. Our synthesis step entails a potentiostatic mode that enables electrophoresis and water electrolysis simultaneously to produce free-standing conductive hydrogels with high porosity. Materials characterization of the as-synthesized composite hydrogels confirm reasonable electric conductivity and impressive anti-bacterial performance. In addition, structural and compositional analysis such as SEM, EDX, XPS, and Raman spectroscopy are conducted. From in-vitro tests of fibroblast cells, we observe that the application of electrical signals accelerates the growth rate, and the resulting current responses are contingent on the magnitude of cell proliferation. Our composite hydrogels combine both electrical stimulation and detection functionality, desirable attributes for potential use in wound healing application.
A novel ultrasonography-guided high intensity focused ultrasound (HIFU) system (FS-100; Force Electronics Co. Ltd, Chongqing, China) was developed for non-invasive thermal ablation of tumor. The proprietary therapy delivery system is an integration of the digital image progressing, automatic control and the high intensity focused ultrasound thermal ablation devices. The therapeutic ultrasound probe (φ = 240 mm) consists of eight circular HIFU transducers with a curved surface of a diameter of 60 mm. Dual focused beams generated from the probe were used in this system for thermal delivery. The probe has the maximal resonance frequency of 1 MHz, a maximal treatment depth of 160 mm and focal spot diameter of 3 mm. The maximal intensity at the focal spot is 10,000 W/cm 2 . The imaging and HIFU components are located on top of the device, therefore, the focused ultrasound beams can be delivered to the patient in a supine position. The motion, targeting and localization of the probe are controlled by a PMAC-PC motion controller and an 8-independent-axis mechanical device. The linear motion error of the probe localization is ≤ 0.1 mm. The ultrasonographic image information is used for treatment planning and therapeutic interventions, such as target definition and registration, visualization of the three-dimensional anatomy of desired target(s), automatic positioning the thermal beams on targets, controlling thermal delivery, and rapid evaluation of target response post-treatment. The preclinical experimental results will be presented. The safety, feasibility and effectiveness of this novel HIFU system will be tested.
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