An official website of the United States government
Abstract Light addressable electrochemical (LAE) sensors have seen great utility in the past several years because they enable multiple localized electrochemical measurements to be performed on a single macroscopic electrode, opening up applications in imaging, biosensing, surface patterning, and multiplexing. In this study, we investigated the effects of electrodeposition on the formation of LAE sensors formed between n‐Si and electrodeposited Pt. We prepared sensors by electrodepositing Pt onto freshly‐etched n‐Si under a variety of conditions, varying the Pt precursor concentration, electrodeposition time, supporting electrolyte, and potential waveform. We characterized the sensors using a combination of atomic force microscopy, electrochemical impedance spectroscopy, and cyclic voltammetry. This study shows that the electrodeposition parameters have a dramatic impact on the morphology of the electrodeposited surfaces, sensor stability, and sensitivity towards H2O2. Specifically, we observed that continuous Pt films prepared with a higher Pt precursor concentration were more stable and had better linearity, higher sensitivity, and broader dynamic range than those prepared with a lower Pt precursor concentration. The stability and increased H2O2sensing performance correlate strongly with an increase in the Pt islands which make up the film. These data highlight that the morphology of the metal in semiconductor/metal junction LAE sensors has an impact on important performance metrics like stability and sensitivity. They also demonstrate the need for semiconductor/metal LAE sensors to be studied using micro‐ and nanoscale imaging techniques in order to more deeply understand their performance characteristics.
more »
« less
Editors’ Choice—Luminescent Oxygen Sensors: Valuable Tools for Spatiotemporal Exploration of Metabolism in In Vitro Systems
A common biological theme on Earth is the importance of oxygen, regardless of an organism’s metabolic capabilities. This commonality makes the quantification of O2essential in understanding life as we know it. There are many sensing methods that enable researchers to measure this important analyte, but not all sensors are compatible with every system. This perspective highlights common O2sensing formats (and recent innovations) with the goal of guiding the reader towards a sensor choice for their desired application. We emphasize the importance of exploring unfamiliar metabolic processes, commercializing new sensors, and establishing collaborations for maximizing innovation and accelerating discovery.
more »
« less
- Award ID(s):
- 1944204
- PAR ID:
- 10429318
- Publisher / Repository:
- The Electrochemical Society
- Date Published:
- Journal Name:
- ECS Sensors Plus
- Volume:
- 2
- Issue:
- 3
- ISSN:
- 2754-2726
- Page Range / eLocation ID:
- Article No. 032401
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
More Like this
-
-
This article deals with reliable and unreliable mobile sensors having identical sensing radiusr, communication radiusR, provided thatr≤Rand initially randomly deployedon the planeby dropping them from an aircraft according to general random process. The sensors have to move from their initial random positions to the final destinations to provide greedy pathk1-coverage simultaneously withk2-connectivity. In particular, we are interested in assigning the sensing radiusrand communication radiusRto minimizethe time requiredandthe energy consumptionof transportation cost for sensors to provide the desiredk1-coverage withk2-connectivity. We prove that for both of these optimization problems, the optimal solution is to assign the sensing radius equal tor=k1||E[S]||/2 and the communication radiusR=k2||E[S]||/2, where ||E[S]|| is the characteristic of general random process according to which the sensors are deployed. Whenr<k1||E[S]||/2 orR<k2||E[S]||/ 2, and sensors are reliable, we discover and explainthe sharp increasein the time required and the energy consumption in transportation cost to ensure the desiredk1-coverage withk2-connectivity.more » « less
-
Abstract Flexible and wearable sensors show enormous potential for personalized healthcare devices by real‐time monitoring of an individual's health. Typically, a single functional material is selected for one sensor to sense a particular physical signal while multiple materials will be selected for multi‐mode sensing. Vertically aligned nanocomposites (VANs) have recently demonstrated various material combinations and novel coupled multifunctionalities that are hard to achieve in any single‐phase material alone, including multiphase multiferroics, magneto‐optic coupling, and strong magnetic and optical anisotropy. Integrating these novel VANs into wearable sensors shows enormous potential in multi‐mode sensing owing to their multifunctional nature. In this work, the transfer of VANs onto polydimethylsiloxane as a novel flexible chemical and pressure sensor is demonstrated. For this demonstration, the classical BaTiO3‐Au VAN with combined plasmonic and piezoelectric properties is used to demonstrate a multi‐sensing mechanism. A thin water‐soluble buffer of Sr3Al2O6serves as a buffer layer for the epitaxial growth and transfer process. The electrical output based on the piezoelectric responses and identifying 4‐mercaptobenzoic acid by surface‐enhanced Raman spectroscopy reveal great potential for free‐standing VANs in a wearable multifunctional sensing platform.more » « less
-
Abstract Diel variations in oxygen concentration have been extensively used to estimate rates of photosynthesis and respiration in productive freshwater and marine ecosystems. Recent improvements in optical oxygen sensors now enable us to use the same approach to estimate metabolic rates in the oligotrophic waters that cover most of the global ocean and for measurements collected by autonomous underwater vehicles. By building on previous methods, we propose a procedure to estimate photosynthesis and respiration from vertically resolved diel measurements of oxygen concentration. This procedure involves isolating the oxygen variation due to biological processes from the variation due to physical processes, and calculating metabolic rates from biogenic oxygen changes using linear least squares analysis. We tested our method on underwater glider observations from the surface layer of the North Pacific Subtropical Gyre where we estimated rates of gross oxygen production and community respiration both averaging 1.0 mmol O2m−3d−1, consistent with previous estimates from the same environment. Method uncertainty was computed as the standard deviation of the fitted parameters and averaged 0.6 and 0.5 mmol O2m−3d−1for oxygen production and respiration, respectively. The variability of metabolic rates was larger than this uncertainty and we were able to discern covariation in the biological production and consumption of oxygen. The proposed method resolved variability on time scales of approximately 1 week. This resolution can be improved in several ways including by measuring turbulent mixing, increasing the number of measurements in the surface ocean, and adopting a Lagrangian approach during data collection.more » « less
-
Abstract Beta gallium oxide (β‐Ga2O3) has emerged as a highly promising semiconductor material with an ultrawide bandgap ranging from 4.5 to 4.9 eV for future applications in power electronics, optoelectronics, as well as gas and ultraviolet (UV) radiation sensors. Here, surface adsorption and air damping behavior of doubly clamped β‐Ga2O3nanomechanical resonators are probed and systemically studied by measuring the resonance characteristics under different gas and pressure conditions. High responsivities of resonance to pressure are obtained by heating the devices up to 300 °C to induce an accelerated adsorption–desorption process. The initial surface conditions of the β‐Ga2O3thin film play important roles in affecting the resonant behavior. UV ozone treatment proves effective in altering the initial surface conditions of β‐Ga2O3nanosheets by eliminating physisorbed contaminants and filling oxygen vacancy defects residing on the surface, resulting in a consequential and discernible modification of the resonance behavior of β‐Ga2O3nanomechanical resonators. The surface adsorption and desorption processes in β‐Ga2O3demonstrate clear reversibility by exposing the UV treated β‐Ga2O3to air. This study attains first‐hand information on how the surface conditions of β‐Ga2O3affect its mechanical properties, and helps guide future development of transducers via β‐Ga2O3nanoelectromechanical systems (NEMS) for pressure sensing applications, especially in harsh environments.more » « less
