An official website of the United States government
Prior research has found that harmonic radar systems are able to detect the presence of electronic devices, even if the devices are powered off. These systems could be a powerful tool to help mitigate privacy invasions. For example, in a rental property devices such as cameras or microphones may be surreptitiously placed by a landlord to monitor renters without their knowledge or consent. A mobile harmonic radar system may be able to quickly scan the property and locate all electronic devices. The effective range of these systems for detecting consumer-grade electronics, however, has not been quantified. We address that shortcoming in this paper and evaluate a prototype harmonic radar system. We find the system, a variation of what has been proposed in the literature, is able to reliably detect some devices at a range of about two meters. We discuss the effect of hardware on the range of detection and propose an algorithm for automated detection.
more »
« less
Detecting Battery Cells with Harmonic Radar
Harmonic radar systems have been shown to be an effective method for detecting the presence of electronic devices, even if the devices are powered off. Prior work has focused on detecting specific non-linear electrical components (such as transistors and diodes) that are present in any electronic device. In this paper we show that harmonic radar is also capable of detecting the presence of batteries. We tested a proof-of-concept system on Alkaline, NiMH, Li-ion, and Li-metal batteries. With the exception of Li-metal coin cells, the prototype harmonic radar detected the presence of batteries in our experiments with 100% accuracy.
more »
« less
- Award ID(s):
- 1955805
- PAR ID:
- 10528551
- Publisher / Repository:
- ACM
- Date Published:
- ISBN:
- 9798400705823
- Page Range / eLocation ID:
- 231 to 236
- Subject(s) / Keyword(s):
- Security and privacy Security in hardware Embedded systems security
- Format(s):
- Medium: X
- Location:
- Seoul Republic of Korea
- Sponsoring Org:
- National Science Foundation
More Like this
-
-
Smart home electronic devices invisibly collect, process, and exchange information with each other and with remote services, often without a home occupants' knowledge or consent. These devices may be mobile or fixed and may have wireless or wired network connections. Detecting and identifying all devices present in a home is a necessary first step to control the flow of data, but there exists no universal mechanism to detect and identify all electronic devices in a space. In this paper we present ICED (Identification and Classification of Electronic Devices), a system that can (i) identify devices from a known set of devices, and (ii) detect the presence of previously unseen devices. ICED, based on harmonic radar technology, collects measurements at the first harmonic of the radar's transmit frequency. We find that the harmonic response contains enough information to infer the type of device. It works when the device has no wireless network interface, is powered off, or attempts to evade detection. We evaluate performance on a collection of 17 devices and find that by transmitting a range of frequencies we correctly identify known devices with 97.6% accuracy and identify previously unseen devices as ‘unknown’ with 69.0% balanced accuracy.more » « less
-
Lithium metal batteries are capable of pushing cell energy densities beyond what is currently achievable with commercial Li-ion cells and are the ideal technology for supplying power to electronic devices at low temperatures (≤−20 °C). To minimize the thermal management requirements of these devices, batteries capable of both charging and discharging at these temperatures are highly desirable. Here, we report >4 V Li metal full cell batteries (N/P = 2) capable of hundreds of stable cycles down to −40 °C, unambiguously enabled by the introduction of cation/anion pairs in the electrolyte. Via controlled experimental and computational investigations in electrolytes employing 1,2-dimethoxyethane as the solvating solvent, we observed distinct performance transitions in low temperature electrochemical performance, coincident with a shift in the Li + binding environment. The performance advantages of heavily ion-paired electrolytes were found to apply to both the cathode and anode, providing Li metal Coulombic efficiencies of 98.9, 98.5, and 96.9% at −20, −40, and −60 °C, respectively, while improving the oxidative stability in support of >4 V cathodes. This work reveals a strong correlation between ion-pairing and low-temperature performance while providing a viable route to Li metal full batteries cycling under extreme conditions.more » « less
-
Abstract Solid‐state lithium metal batteries with garnet‐type electrolyte provide several advantages over conventional lithium‐ion batteries, especially for safety and energy density. However, a few grand challenges such as the propagation of Li dendrites, poor interfacial contact between the solid electrolyte and the electrodes, and formation of lithium carbonate during ambient exposure over the solid‐state electrolyte prevent the viability of such batteries. Herein, an ultrathin sub‐nanometer porous carbon nanomembrane (CNM) is employed on the surface of solid‐state electrolyte (SSE) that increases the adhesion of SSE with electrodes, prevents lithium carbonate formation over the surface, regulates the flow of Li‐ions, and blocks any electronic leakage. The sub‐nanometer scale pores in CNM allow rapid permeation of Li‐ions across the electrode–electrolyte interface without the presence of any liquid medium. Additionally, CNM suppresses the propagation of Li dendrites by over sevenfold up to a current density of 0.7 mA cm−2and enables the cycling of all‐solid‐state batteries at low stack pressure of 2 MPa using LiFePO4cathode and Li metal anode. The CNM provides chemical stability to the solid electrolyte for over 4 weeks of ambient exposure with less than a 4% increase in surface impurities.more » « less
-
Data about users is collected constantly by phones, cameras, Internet websites, and others. The advent of so-called ‘Smart Things’ now enable ever-more sensitive data to be collected inside that most private of spaces: the home. The first step in helping users regain control of their information (inside their home) is to alert them to the presence of potentially unwanted electronics. In this paper, we present a system that could help homeowners (or home dwellers) find electronic devices in their living space. Specifically, we demonstrate the use of harmonic radars (sometimes called nonlinear junction detectors), which have also been used in applications ranging from explosives detection to insect tracking. We adapt this radar technology to detect consumer electronics in a home setting and show that we can indeed accurately detect the presence of even ‘simple’ electronic devices like a smart lightbulb. We evaluate the performance of our radar in both wired and over-the-air transmission scenarios.more » « less
- Free Publicly Accessible Full Text
-
Accepted Manuscript1.0
- Conference Paper:
- https://doi.org/10.1145/3643833.3656137
