A nanomesh electrode for self-driven perovskite photodetectors with tunable asymmetric Schottky junctions

Nanoscale ◽  
2021 ◽  
Author(s):  
Meng Zhang ◽  
Youdi Hu ◽  
Shuaiqi Wang ◽  
Yaru Li ◽  
Chunwu Wang ◽  
...  
Keyword(s):  
Nanosphere Lithography ◽  
New Device ◽  
Device Architecture ◽  
Schottky Junctions ◽  
Hexagonally Ordered ◽  
Lithography Technique

We report a new device architecture for self-driven photodetectors with tunable asymmetric Schottky junctions based on a nanomesh electrode. It is composed of a hexagonally ordered nanoelectrode array fabricated via the nanosphere lithography technique.

TiO2Nanoparticle Arrays Prepared Using a Nanosphere Lithography Technique

Nano Letters ◽  
2002 ◽  
Vol 2 (7) ◽  
pp. 739-745 ◽  
Author(s):  
Heather A. Bullen ◽  
Simon J. Garrett
Keyword(s):  
Nanosphere Lithography ◽  
Lithography Technique

scholarly journals Chemical to Electrical Transduction using Fuel Cell Powered Organic Electrochemical Transistors

2020 ◽  
Author(s):  
Siew Ting Melissa Tan ◽  
Alexander Giovannitti ◽  
Armantas Melianas ◽  
Maximilian Moser ◽  
Benjamin L. Cotts ◽  
...  
Keyword(s):  
Electron Transfer ◽  
Fuel Cell ◽  
Health Monitoring ◽  
Active Material ◽  
Design Parameters ◽  
Side Reactions ◽  
Enzymatic Reactions ◽  
New Device ◽  
Device Architecture ◽  
Electrochemical Transistor

<p>Electrochemical transistors have recently gained significant attention in the field of bioelectronics. In particular, the organic electrochemical transistor (OECT), a device that employs organic semiconductors as the active material, has been widely investigated as biosensors due to their low operational potentials, ability to operate in aqueous environments, biocompatibility, and the amplification of low-lying biological signals owing to the OECTs’ large transconductance. As such, OECTs have been utilized as biochemical sensors for monitoring of biomarkers or metabolites, with potential application for health monitoring for wearable devices in combination with internet of things (IoT). </p> <p>The current working principle of biosensors based on OECTs relies on the reaction between the channel material and the analyte or intentionally generated intermediates that undergo direct or indirect electron transfer reactions with the channel material. This electron transfer reaction results in changes of the device channel conductivity with respect to the concentration of the analyte in a sample. While recent work has shown progress in development of biosensors based on this approach, it introduces several complications and disadvantages, namely unintended and uncontrolled chemical and electrochemical side reactions. First and foremost, this configuration does not allow the signal amplification one expects from a transistor device, thus invalidating the most often (and we show here erroneously) stated advantages of using OECTs for biosensing. Further, devices designed using this approach can rapidly degrade during the operation but more importantly, the results and their interpretation can lead to incorrect conclusions and render current devices unreliable for applications in health monitoring. </p> <p>Our work addresses these challenges by i) isolating the chemical reaction from the OECT channel on a separate compartment and ii) employing enzymatic reactions to form intermediates that drives a reaction to power the OECT. In addition, this device architecture eliminates the need for an external gate voltage so only a single power source is required to monitor changes of the conductivity of the OECT channel material. Doing so also allows us to <u>truly</u> amplify the reaction current on the fuel cell from µA up to mA across the OECT (with ON/OFF ratios of 10<sup>4</sup>), presenting significant improvements over conventional OECT biosensors that operate in the nA range, thereby eliminating the need for sophisticated measurement instrumentation. Our work goes in depth in elucidating general materials design parameters for the fuel cell OECT. Furthermore, the device operation mechanism was rationalized using electrochemical and electrical measurements of a variety of state-of-the-art materials for OECTs.</p> The development of this new device architecture presents an exciting new direction for sensing of metabolites and a low power, low cost and simple alternative approach to current technologies. Importantly, we also challenge some of the current thinking in the field of OECT-based biosensing. We believe that our findings will be of great interest to researchers in the fields of bioelectronics, biofuel cells and organic electronics. Additionally, our findings shine light on the working mechanism of enzymatic biosensors with OECTs. We believe that our approach will pave the way for implementation of OECT biosensors in real life applications due to the simplification of the backend circuitry that powers and synchronizes the gate and drain voltages.

scholarly journals Two-dimensional arrays of vertically packed spin-valves with picoTesla sensitivity at room temperature

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Marilia Silva ◽  
Fernando Franco ◽  
Diana C. Leitao ◽  
Susana Cardoso ◽  
Paulo P. Freitas
Keyword(s):  
Room Temperature ◽  
Spin Valve ◽  
Spin Valves ◽  
Two Dimensional ◽  
Detection Level ◽  
New Device ◽  
Device Architecture ◽  
In Series ◽  
Magnetic Couplings ◽  
Lower Noise

AbstractA new device architecture using giant magnetoresistive sensors demonstrates the capability to detect very low magnetic fields on the pT range. A combination of vertically packed spin-valve sensors with two-dimensional in-plane arrays, connected in series and in parallel, delivers a final detection level of 360 pT/$$\sqrt{Hz}$$ Hz at 10 Hz at room temperature. The device design is supported by an analytical model developed for a vertically packed spin-valve system, which takes into account all magnetic couplings present. Optimization concerning the spacer thickness and sensor physical dimensions depending on the number of pilled up spin-valves is necessary. To push the limits of detection, arrays of a large number of sensing elements (up to 440,000) are patterned with a geometry that improves sensitivity and in a configuration that reduces the resistance, leading to a lower noise level. The final device performance with pT detectivity is demonstrated in an un-shielded environment suitable for detection of bio-signals.

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