Emerging physical unclonable functions with nanotechnology

Physical unclonable functions (PUFs) are increasingly used for authentication and identification applications as well as the cryptographic key generation. An important feature of a PUF is the reliance on minute random variations in the fabricated hardware to derive a trusted random key. Currently, most PUF designs focus on exploiting process variations intrinsic to the CMOS technology. In recent years, progress in emerging nanoelectronic devices has demonstrated an increase in variation as a consequence of scaling down to the nanoregion. To date, emerging PUFs with nanotechnology have not been fully established, but they are expected to emerge. Initial research in this area aims to provide security primitives for emerging integrated circuits with nanotechnology. In this paper, we review emerging nanotechnology-based PUFs

Advancing fabrication and properties of three-dimensional graphene-alginate scaffolds for application in neural tissue engineering

Neural tissue engineering provides enormous potential for restoring and improving the function of diseased/damaged tissues and promising opportunities in regenerative medicine, stem cell technology, and drug discovery. The conventional 2D cell cultures have many limitations to provide informative and realistic neural interactions and network formation. Hence, there is a need to develop three-dimensional (3D) bioscaffolds to facilitate culturing cells with matched microenvironment for cell growth and interconnected pores for penetration and migration of cells. Herein, we report the synthesis and characterization of 3D composite bioscaffolds based on graphene-biopolymer with porous structure and improved performance for tissue engineering. A simple, eco-friendly synthetic method is introduced and optimized for synthesis of this hybrid fibrous scaffold by combining Graphene Oxide (GO) and Sodium Alginate (Na-ALG) which are specifically selected to match the mechanical strength of the central nervous system (CNS) tissue and provide porous structure for connective tissue engineering. Properties of the developed scaffold in terms of the structure, porosity, thermal stability, mechanical properties, and electrical conductivity are presented. These properties were optimised through key synthesis conditions including GO concentrations, reduction process and crosslinking time. In contrast to other studies, the presented structure maintains its stability in aqueous media and uses a bio-friendly reducing agent which enable the structure to enhance neuron cell interactions and act as nerve conduits for neurological diseases.Negar Mansouri, Said F. Al-Sarawi, Jagan Mazumdar and Dusan Losi

Low cost reactively matched broadband GaAs MMIC power amplifier for airborne applications

A highly efficient, single stage broadband power amplifier was designed and fabricated in WIN Semiconductor 0.10 μm GaAs technology. Reactive matching networks were used to optimize the broadband performance in Class AB topology. This was obtained by iterating the load and source fundamental impedances to achieve the highest PAE with the second harmonic load termination short circuited. Measured results at 10 GHz show a saturated output power of around 27 dBm, drain efficiency as high as 71.2% and a PAE of 64.1% with a small signal gain of 16.5 dB and a large signal gain of 12.9 dB. The amplifier has excellent broadband characteristics and the highest reported drain efficiency (DE) of over 50% between 7-13 GHz.Aaron Pereira, Said Al-Sarawi, Neil Weste, Vincenzo Carrubb

Compact second-order bandstop filter based on dual-mode complementary split-ring resonator

A compact dual-mode bandstop filter is presented in this letter. From an equivalent circuit viewpoint, a second-order response is obtained by designing a two-pole notch filter with inductive coupling. This equivalent circuit is then implemented by using a dual-mode complementary split-ring resonator. The proposed bandstop filter prototype has dimensions of 0.1g 0.18g, where {g} defines the guided-wave wavelength. An experimental validation at the center frequency 0 of 2 GHz shows that the proposed filter can extend the harmonic-free upper passband up to 4.20

Dual-mode behavior of the complementary electric-LC resonators loaded on transmission line: Analysis and applications

Abstract not available.Amir Ebrahimi, Withawat Withayachumnankul, Said F. Al-Sarawi, and Derek Abbot

PUF sensor: exploiting PUF unreliability for secure wireless sensing

Wireless sensors are increasingly penetrating every domain of our lives through integration with Internet of Things, e.g., such devices are widely incorporated into smart buildings and for monitoring critical industrial infrastructure. Sensing, collecting and communication of sensor data, however, are under threat from various attacks due to the difficulty in implementing proper protection mechanisms and limited computational resources available in these cost-sensitive devices. This paper expands on recent research on physical unclonable function (PUF) sensors to secure sensing by taking the advantage of inherent physical randomness. In particular, PUF unreliability originates from its sensitivity to ambient parameter variations that is usually undesirable for elementary PUF applications-such as authentication and key generation-is exploited to guarantee the veracity of the sensed value. In this paper, a PUF naturally acting as a sensor or a PUF explicitly integrated with a sensor is called a PUF sensor. Security of sensing in a PUF sensor is attributed to the natural merging of cryptography and sensing to eschew the need for a standalone crypto module. Thus, the PUF sensor is appealing for low-cost applications. To obtain the sensed value, we develop an authenticated sensing protocol that is robust against eavesdropping, also capable of detecting man-in-the-middle manipulation of the sensed value. Compared to initial investigations of PUF sensors, we avoid the stringent requirements of a strong PUF. We validate the feasibility of the proposed authenticated sensing protocol based on an experimental implementation of a ring oscillator PUF sensor. To improve the sensing capability, we present an efficient approach to select sensitive responses and only employ them for sensing. Significantly improved efficacy is validated through comprehensive experimental results.Yansong Gao, Hua Ma, Derek Abbott, Said F. Al-Saraw

Varactor-tunable second-order bandpass frequency-selective surface with embedded bias network

A varactor-tunable second-order bandpass frequency-selective surface (FSS) for microwave frequencies is presented in this article. The FSS is composed of three stacked metallic layers. The wire grid in each layer in combination with metallic vias provides the bias for the varactors. This configuration eliminates the need for a dedicated bias network for the varactors, and thus avoids undesirable responses associated with the added bias grid. An equivalent circuit model together with an analytical design method is provided to simplify the design procedure of the FSS. The performance of the proposed structure is experimentally validated in a parallel-plate waveguide setup. Measurements show that by changing the varactor capacitance from 0.12 to 0.38 pF, the center frequency of the filter is tuned from 5.2 to 3.7 GHz with a consistent fractional bandwidth of 9% and with an insertion loss between 3 and 6 dB

A fully integrated hybrid power management unit for passive UHF RFID in 130-nm process

This paper presents a fully integrated hybrid power management unit (HPMU) realized in the 130-nm complementary metal-oxide-semiconductor. The design improves the performance of RFID tags-especially those with passively powered sensors-by intelligently managing harvested power. The HPMU opportunistically takes advantage of the excess harvested power beyond the operational requirements of a tag and stores this energy externally. Through smart power routing, this stored energy is used to sustain the supply voltage of tag circuitry. This approach can reduce cold start-up time, mitigate consequences of brownouts and, effectively, extend the operational range and the responsiveness of tags-especially those with passively powered sensors. In addition, the HPMU switches off when the harvested power, indicative of a weak interrogating signal, is too low to conserve stored power. The entire HPMU has been optimized for low power consumption, which not only reduces the power overhead that HPMU introduces, but also ensures that as much power as possible is siphoned and stored rather than dissipated in the power management circuitry. In off state, the HPMU consumes only around 10 nA from the external storage element and during charge storage mode of operation, the HPMU has a peak conversion efficiency of approximately 65%.Menghan Sun, Said F. Al-Sarawi, Peter Ashenden, Mario Cavaiuolo, Damith C. Ranasingh

Obfuscated challenge-response: A secure lightweight authentication mechanism for PUF-based pervasive devices

Low cost pervasive devices such as RFID (radio-frequency identification) tags and sensor nodes are increasingly becoming part of the fabric of life. Using these pervasive devices to store and collect data securely is becoming a challenge because stringent requirements on power and area constrain the implementation of standard cryptographic mechanisms. In this paper, we propose a secure and lightweight authentication protocol for resource scarce pervasive devices built upon a physical unclonable function (PUF) primitive termed Obfuscated PUF (OB-PUF) and a variant of a parameter-based authentication protocol. This protocol sends obfuscated challenges to an OB-PUF where the subsequent recovery of the obfuscated challenges by a server (verifier) is guaranteed. In particular, our approach exploits server (verifer) aided computations to reduce the hardware complexity on the pervasive device while still maintaining a high level of security and taking advantage of the known vulnerability of PUFs to model building attacks. Most importantly, the unclonability of the OB-PUF is preserved and, consequently, OB-PUF based pervasive devices are resilient to cloning. We also show through statistical analysis and model building attacks the infeasibility of constructing a model of our proposed OB-PUF by an adversary