Methyl ammonium lead iodide (MAPbI3) was one of the earliest perovskite formulations examined, which created tremendous interest in these materials given their stupendous rise in power conversion efficiency (PCE). Beyond MAPbI3, new perovskite formulations have emerged, such as the triple cation (Cs0.05FA0.79MA0.16PbI2.45Br0.55) absorbers, which have further advanced research in emerging photovoltaics in addition to other types of optoelectronics sensors. Given the stability issues with many of the perovskites, here we explore how the environmental ambient influences the device stability through in-use testing.
Graphene, a single sheet of carbon atoms arranged in a two-dimensional (2-D) honeycomb lattice extracted from bulk three-dimensional (3-D) graphite, has shown great promise towards low-profile sensing applications. Several studies have demonstrated its potential in acquiring 2-D electrophysiological measurements of the human body including the use of electromyography (EMG). Electromyograms require a minimum of two electrodes, making them a cost-effective option for the study of 2-D conductors interfaced to the human body. Although EMG signals are typically no more than 5 mV, they can be easily visualized through amplification with a gain resistor on a prototype circuit. In this study, preliminary EMG measurements of antagonist-agonist muscle pairs are collected through utilization of commercial electrodes to yield statistically significant results on the effect of gain on the Signal-to-Noise-Ratio (SNR) and on quantitative measurements of muscle force and associated amplitude. This information is then applied towards the exploration of producing graphene electrodes for biosensing. Presently, there have been limited studies on inkjet-printed electrodes for this purpose, with methods typically favoring screen-printing techniques. Therefore, there is value in analyzing reliable fabrication methods with graphene ink towards the production of devices for strain-dependent sensing and biosensing. To do this, graphene ink was processed via liquid-phase exfoliation with a mixture of graphite powder with typical solvents and other additives. This ink was printed on an SiO2/Si substrate to form electrodes for voltage testing in addition to electrode formation on flexible substrates for dynamic strain sensing. Here the conductivity was verified through strain-dependent testing, and the flexible graphene devices demonstrated live current changes at variable bending angles and in opposite profiles which we discuss in this work.
Sensing temperature is important for a wide variety of applications such as control systems and instrumentation which are integral to various industrial sectors and in research settings. To date, many prior studies have favored the use of the resistive thermistor approach given its simplicity. However, such devices are less sensitive to temperature changes compared to frequency-dependent approaches which are gaining momentum for detection. The importance of high sensitivity and reliable methods using a frequency-based approach for detecting temperature changes should thus be apparent, particularly if such sensors are also fabricated using low-cost approaches which are amenable toward miniaturized wireless platforms at the same time. In this study, Au rectangular single-arm spiral antennas with varying sizes were fabricated and RF S-parameter measurements were conducted over the frequency range of 300 kHz to 20 GHz. Solution-processed, two-dimensional (2D) hexagonal boron nitride (h-BN) was used with cyclohexanone and terpineol as solvents, and the films were characterized using dc current-voltage and frequency-dependent capacitance measurements. We also characterized our solution-processed h-BN films using Raman spectroscopy. The shift in the resonant frequency through the addition of h-BN over the underlying Au antenna was observed as this dielectric was coated on top of the antennas and the temperature response of the resonance frequency was measured. Alongside the experimental measurements, we also present results from our simulation analysis conducted using High Frequency Structure Simulator (HFSS) from ANSYS.
Access to the requested content is limited to institutions that have purchased or subscribe to SPIE eBooks.
You are receiving this notice because your organization may not have SPIE eBooks access.*
*Shibboleth/Open Athens users─please
sign in
to access your institution's subscriptions.
To obtain this item, you may purchase the complete book in print or electronic format on
SPIE.org.
INSTITUTIONAL Select your institution to access the SPIE Digital Library.
PERSONAL Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.