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  1. Free, publicly-accessible full text available February 1, 2023
  2. Photoacoustic laser streaming provides a versatile technique to manipulate liquids and their suspended objects with light. However, only gold was used in the initial demonstrations. In this work, we first demonstrate that laser streaming can be achieved with common non-plasmonic metals such as Fe and W by their ion implantations in transparent substrates. We then investigate the effects of ion dose, substrate material and thickness on the strength and duration of streaming. Finally, we vary laser pulse width, repetition rate and power to understand the observed threshold power for laser streaming. It is found that substrate thickness has a negligiblemore »effect on laser streaming down to 0.1 mm, glass and quartz produce much stronger streaming than sapphire because of their smaller thermal conductivity, while quartz exhibits the longest durability than glass and sapphire under the same laser intensity. Compared with Au, Fe and W with higher melting points show a longer lifetime although they require a higher laser intensity to achieve a similar speed of streaming. To generate a continuous laser streaming, the laser must have a minimum pulse repetition rate of 10 Hz and meet the minimum pulse width and energy to generate a transient vapor layer. This vapor layer enhances the generation of ultrasound waves, which are required for observable fluid jets. Principles of laser streaming and temperature simulation are used to explain these observations, and our study paves the way for further materials engineering and device design for strong and durable laser streaming.« less
  3. A subthreshold hybrid PUF-embedded authentication circuit is proposed to mitigate the financial incentives that drive the counterfeit community and to encourage the COTS manufacturers to use authentication for system identification in their parts. The proposed hybrid PUF with cross-coupled inverters and a delay-based PUF strategy has sufficient entropy for authentication and a reduced number of transistors per bit. The area efficient fingerprint circuit does not require additional die area, pins, or power overhead. The performance of the primary circuit is unaffected by the fingerprint circuit. The hybrid circuit designed in a 65 nm CMOS process is discussed.
  4. One aspect of system security is evaluating a system’s vulnerability to Trojan attack. A hardware Trojan attack can have potentially devastating effects, especially given the increased reliance on integrated circuits within critical systems. A significant amount of research concerns attacks on digital systems, but attacks on AMS and RF systems have recently been of interest as well. A class of Trojans has been proposed that uses undesired alternate modes of operation in nonlinear systems as the Trojan payload. These Trojans are of particular interest because they do not cause deviations from the ideal system performance and cannot be detected untilmore »the Trojan is triggered. This work addresses this class of Trojans by listing different payloads, trigger mechanisms, and examples of system architectures vulnerable to attack.« less
  5. Hardware security vulnerabilities to hardware Trojans in widely used filter structures are identified. The widely used two-integrator loop filter architecture known as the Kerwin-Huelsman-Newcomb (KHN) Biquad is used to demonstrate the vulnerability. It is shown that the relationship between the passive component values and the nonlinear amplifier parameters, the slew rate and the output saturation voltages, determine the presence or absence of a stationary nonlinear undesired oscillatory mode of operation. Experimental results obtained from a discrete component filter demonstrate the vulnerability to the Trojan mode of operation in this filter structure.