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This work presents a pH sensor platform combining the high performance of iridium oxide (IrOx) fabricated by cyclic voltammetry with inductively-coupled wireless (ICW) transmission. Data included presents flexible potentiometric pH sensors having IrOx as the sensing electrode and a cured Ag/AgCl paste as the pseudo-reference electrode; further investigations concerning performance tailoring via fabrication processes are shown. The fabricated sensors show the best performance with a probe surface area of ${1}\times {1}$ mm2, electrodeposited for 100 cyclic voltammetry (CV) sweeps, at 100 mV/s. The sensitivity of the fabricated sensor is typically in the range of 65–75 mV/pH, as tested using either pH 4–9 (six points) or 2–10 (five points) buffers. The sensors exhibiting those sensitivities in buffer solutions yielded a response from “artificial sweat” solutions differing by ~0.4–0.8 pH from a commercial glass pH electrode, while limit-of-quantification (LOQ) was measured to be ~0.04–0.08 pH. The sensing electrode shows a response time of less than 2 seconds and minimal hysteresis effects. Cationic interferences from up to 1M Na+ resulted in +3–8 mV/pH changes in sensitivity, depending on solution pH and probe, with minimal effects to LOQ. The performance under different bending conditions (0°, 30° at 55 mm radius, 45° at 37 mm, and 90° at 20 mm) of the flexible sensor probe show negligible variation. Finally, the presented sensors were integrated with an inductively coupled wireless (ICW) communication system for a demonstration of online monitoring. This sensor platform can easily be miniaturized due to a low count of necessary components and absence of onboard energy storage. [ABSTRACT FROM AUTHOR]

This communication presents a novel compact broadband circularly polarized (CP) implantable patch antenna for biomedical applications in 2.4 GHz industrial, scientific, and medical (ISM) band. By employing slots on the patch plane and shorting method, the whole size (including the superstrate) of the designed antenna can be enormously reduced to $9.8\times 9.8\times1.27$ mm3, which is equivalent to $0.0784\lambda _{0}\times 0.0784\lambda _ {0}\times 0.0102\lambda _ {0}$ ($\lambda _ {0}$ is the free-space wavelength at 2.4 GHz). Under the premise of keeping a slotless ground, not only a good size reduction is realized but also the impedance bandwidth and the axial ratio (AR) bandwidth are greatly improved. A simulated −10 dB impedance bandwidth of 21.5% with a 3 dB AR bandwidth of 15.8% is acquired in a skin phantom. The antenna also exhibits good robustness to different thicknesses of biocompatible coating. The influence of different body phantoms is discussed to evaluate the sensitivity of the proposed antenna. The experiments are carried out in both skin-mimicking gel and pork, and the respective measured impedance bandwidths are 25.9% and 25.7%. The CP purity is experimentally validated by comparing the communication link levels in two orthogonal polarization directions. The maximum specific absorption rate (SAR) value satisfies the IEEE standard safety guidelines. [ABSTRACT FROM AUTHOR]

This paper demonstrates a methodology for preparing patterned graphene films through the destabilization of dispersed graphene in N-methyl-pyrrolidone (NMP) by addition of water, which causes the graphene to be trapped at the interface of NMP/hexane. The trapped graphene film is transferred onto the patterned wetting/nonwetting surface through dip-coating process. The quality of graphene film is studied by scanning electron microscopy and atomic force microscopy. The sheet resistance of graphene film is 1.49 × 10 ^2 kΩ/□ with surface coverage of 70% measured by the four-probe method. Field effect transistor based on such patterned graphene film is then fabricated. The current on/off ratio of devices is 1.24 with field-effect hole mobility of 159 cm ^2/Vs. [ABSTRACT FROM PUBLISHER]