Picowatt gas sensing and resistance switching in tunneling nano-gap electrodes

Banerjee, Aishwaryadev; Farhoudi, Navid; Ghosh, Chayanjit; Mastrangelo, Carlos H.; Kim, H.; Broadbent, S.; Looper, Ryan

doi:10.1109/icsens.2016.7808637

Cited by 11 publications

(14 citation statements)

References 8 publications

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“…Nanogap electrodes (electrodes separated by a gap of a few nanometers), have been previously used for highly sensitive bio-sensor applications [13][14][15][16]. Similar to other devices built by Mastrangelo et al [17][18][19], these can be used as low-power and highly sensitive tunneling hygrometers for IoT applications.…”

Section: Basic Operating Principle Of Resistive Nanogap Hygrometermentioning

confidence: 99%

Quantum Tunneling Hygrometer with Temperature Stabilized Nanometer Gap

Banerjee

Likhite

Kim

et al. 2020

Sci Rep

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We present the design, fabrication and response of a humidity sensor based on electrical tunneling through temperature-stabilized nanometer gaps. The sensor consists of two stacked metal electrodes separated by ~2.5 nm of vertical air gap. Upper and lower electrodes rest on separate 1.5 μm thick polyimide patches with nearly identical thermal expansion but different gas absorption characteristics. When exposed to a humidity change, the patch under the bottom electrode swells but the patch under the top electrode does not, as it is covered with a watervapor diffusion barrier ~8 nm of Al2O3. The air gap thus decreases leading to increase in the tunneling current across the junction. The gap however is independent of temperature fluctuations as both patches expand or contract by near equal amounts. Humidity sensor action demonstrates an unassisted reversible resistance reduction Rmax/Rmin ~10 5 when the device is exposed to 20 -90 RH% at a standby DC power consumption of ~0.4 pW. The observed resistance change when subject to a temperature sweep of 25 -60° C @24% RH was ~0.0025% of the full device output range.

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Section: Basic Operating Principle Of Resistive Nanogap Hygrometermentioning

confidence: 99%

Quantum Tunneling Hygrometer with Temperature Stabilized Nanometer Gap

Banerjee

Likhite

Kim

et al. 2020

Sci Rep

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“…In this article, we introduce a new batch-fabrication method of nanogap tunneling junctions and we perform an exhaustive characterization of the uniformity of the spacer layer, inspect tunneling current characteristics, and determine the potential barrier of the thin spacer layer as well as the maximum operating voltage for the device. Molecular devices based on this construction method have been previously used as tunneling chemiresistors for bio sensing [15,16,17,18] and are potential candidates for low-power consumption gas sensing devices [19,20,21,22]. The nanogap electrodes are chemically functionalized by coating them with a self-assemble-monolayer (SAM) of thiol molecules.…”

Section: Introductionmentioning

confidence: 99%

“…Preliminary sensing results have demonstrated that these nanogap electrodes can be effectively used as chemiresistors for label-free electrical detection of both gas and proteins after chemical functionalization [15,17]. The junction resistance, which is typically in the order of giga Ohms, drops by several orders of magnitude upon detection of a chemical target.…”

Section: Introductionmentioning

confidence: 99%

Batch-Fabricated α-Si Assisted Nanogap Tunneling Junctions

et al. 2019

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This paper details the design, fabrication, and characterization of highly uniform batch-fabricated sidewall etched vertical nanogap tunneling junctions for bio-sensing applications. The device consists of two vertically stacked gold electrodes separated by a partially etched sacrificial spacer layer of sputtered α-Si and Atomic Layer Deposited (ALD) SiO2. A ~10 nm wide air-gap is formed along the sidewall by a controlled dry etch of the spacer. The thickness of the spacer layer can be tuned by adjusting the number of ALD cycles. The rigorous statistical characterization of the ultra-thin spacer films has also been performed. We fabricated nanogap electrodes under two design layouts with different overlap areas and spacer gaps, from ~4.0 nm to ~9.0 nm. Optical measurements reported an average non-uniformity of 0.46 nm (~8%) and 0.56 nm (~30%) in SiO2 and α-Si film thickness respectively. Direct tunneling and Fowler–Nordheim tunneling measurements were done and the barrier potential of the spacer stack was determined to be ~3.5 eV. I–V measurements showed a maximum resistance of 46 × 103 GΩ and the average dielectric breakdown field of the spacer stack was experimentally determined to be ~11 MV/cm.

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“…In recent decades, miniaturized humidity sensors have been realized using various transduction methods [1][2][3][4][5][6][7] for a wide range of applications such as improving indoor comfort in homes and automobiles, humidity monitoring in semiconductor processing facilities [8], food processing industries [9], medical facilities [10] and, Internet-of-Things (IoT) based frameworks [11]. The push for the need for low-power chemical sensors [12][13][14] has been quite strong due to the growing importance of IoT sensor nodes across the world.…”

Section: Introductionmentioning

confidence: 99%

“…9a shows the equivalent electrical circuit of the LACM sensor. The humidity response of the device was curve-fitted to equation(13), and the plot is shown inFigure 9b. Parameter extraction revealed the mean value of βp ~ 0.114 mN.m -1 per ppm of water vapor and the value of fitting parameters Ao and Bo ranged from 2.5 to 12 and -0.06 to -0.01, respectively.…”

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confidence: 99%

Parametrically Amplified Low-Power MEMS Capacitive Humidity Sensor

Likhite

Banerjee

Majumder

et al. 2019

Preprint

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We present the design, fabrication, and response of a polymer-based Laterally Amplified Chemo-Mechanical (LACM) humidity sensor based on mechanical leveraging and parametric amplification. The device consists of a sense cantilever asymmetrically patterned with a polymer and flanked by two stationary electrodes on the sides. When exposed to a humidity change, the polymer swells after absorbing the analyte and causes the central cantilever to bend laterally towards one side, causing a change in the measured capacitance. The device features an intrinsic gain due to parametric amplification resulting in an enhanced signal-to-noise ratio (SNR). 11-fold magnification in sensor response was observed via voltage biasing of the side electrodes without the use of conventional electronic amplifiers. The sensor showed a repeatable and recoverable capacitance change of 11% when exposed to a change in relative humidity from 25-85%. The dynamic characterization of the device also revealed a response time ~1s and demonstrated a competitive response with respect to a commercially available reference chip.

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Picowatt gas sensing and resistance switching in tunneling nano-gap electrodes

Cited by 11 publications

References 8 publications

Quantum Tunneling Hygrometer with Temperature Stabilized Nanometer Gap

Quantum Tunneling Hygrometer with Temperature Stabilized Nanometer Gap

Batch-Fabricated α-Si Assisted Nanogap Tunneling Junctions

Parametrically Amplified Low-Power MEMS Capacitive Humidity Sensor

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