Ultrasensitive interferometric on-chip microscopy of transparent objects

Light microscopes can detect objects through several physical processes, such as scattering, absorption, and reflection. In transparent objects, these mechanisms are often too weak, and interference effects are more suitable to observe the tiny refractive index variations that produce phase shifts. We propose an on-chip microscope design that exploits birefringence in an unconventional geometry. It makes use of two sheared and quasi-overlapped illuminating beams experiencing relative phase shifts when going through the object, and a complementary metal-oxide-semiconductor image sensor array to record the resulting interference pattern. Unlike conventional microscopes, the beams are unfocused, leading to a very large field of view (20 mm(2)) and detection volume (more than 0.5 cm(3)), at the expense of lateral resolution. The high axial sensitivity (<1 nm) achieved using a novel phase-shifting interferometric operation makes the proposed device ideal for examining transparent substrates and reading microarrays of biomarkers. This is demonstrated by detecting nanometer-thick surface modulations on glass and single and double protein layers.Peer ReviewedPostprint (published version

Analysis of Countermeasures Against Remote and Local Power Side Channel Attacks using Correlation Power Analysis

Countermeasures and deterrents to power side-channel attacks targeting the alteration or scrambling of the power delivery network have been shown to be effective against local attacks where the malicious agent has physical access to the target system. However, remote attacks that capture the leaked information from within the IC power grid are shown herein to be nonetheless effective at uncovering the secret key in the presence of these countermeasures/deterrents. Theoretical studies and experimental analysis are carried out to define and quantify the impact of integrated voltage regulators, voltage noise injection, and integration of on-package decoupling capacitors for both remote and local attacks. An outcome yielded by the studies is that the use of an integrated voltage regulator as a countermeasure is effective for a local attack. However, remote attacks are still effective and hence break the integrated voltage regulator countermeasure. From the experimental analysis, it is observed that within the range of designs\u27 practical values, the adoption of on-package decoupling capacitors provides only a 1.3x increase in the minimum number of traces required to discover the secret key. However, the injection of noise in the IC power delivery network yields a 37x increase in the minimum number of traces to discover. Thus, increasing the number of on-package decoupling capacitors or the impedance between locally measured power and the IC power grid should not be relied on as countermeasures to power side-channel attacks, for remote attack schemes. Noise injection should be considered as it is more effective at scrambling the leaked signal to eliminate sensitive identifying information

Systematic Characterization of Power Side Channel Attacks for Residual and Added Vulnerabilities

Power Side Channel Attacks have continued to be a major threat to cryptographic devices. Hence, it will be useful for designers of cryptographic systems to systematically identify which type of power Side Channel Attacks their designs remain vulnerable to after implementation. It’s also useful to determine which additional vulnerabilities they have exposed their devices to, after the implementation of a countermeasure or a feature. The goal of this research is to develop a characterization of power side channel attacks on different encryption algorithms\u27 implementations to create metrics and methods to evaluate their residual vulnerabilities and added vulnerabilities. This research studies the characteristics that influence the power side leakage, classifies them, and identifies both the residual vulnerabilities and the added vulnerabilities. Residual vulnerabilities are defined as the traits that leave the implementation of the algorithm still vulnerable to power Side Channel Attacks (SCA), sometimes despite the attempt at implementing countermeasures by the designers. Added vulnerabilities to power SCA are defined as vulnerabilities created or enhanced by the algorithm implementations and/or modifications. The three buckets in which we categorize the encryption algorithm implementations are: i. Countermeasures against power side channel attacks, ii. IC power delivery network impact to power leakage (including voltage regulators), iii. Lightweight ciphers and applications for the Internet of Things (IoT ) From the characterization of masking countermeasures, an example outcome developed is that masking schemes, when uniformly distributed random masks are used, are still vulnerable to collision power attacks. Another example outcome derived is that masked AES, when glitches occur, is still vulnerable to Differential Power Analysis (DPA). We have developed a characterization of power side-channel attacks on the hardware implementations of different symmetric encryption algorithms to provide a detailed analysis of the effectiveness of state-of-the-art countermeasures against local and remote power side-channel attacks. The characterization is accomplished by studying the attributes that influence power side-channel leaks, classifying them, and identifying both residual vulnerabilities and added vulnerabilities. The evaluated countermeasures include masking, hiding, and power delivery network scrambling. But, vulnerability to DPA depends largely on the quality of the leaked power, which is impacted by the characteristics of the device power delivery network. Countermeasures and deterrents to power side-channel attacks targeting the alteration or scrambling of the power delivery network have been shown to be effective against local attacks where the malicious agent has physical access to the target system. However, remote attacks that capture the leaked information from within the IC power grid are shown herein to be nonetheless effective at uncovering the secret key in the presence of these countermeasures/deterrents. Theoretical studies and experimental analysis are carried out to define and quantify the impact of integrated voltage regulators, voltage noise injection, and integration of on-package decoupling capacitors for both remote and local attacks. An outcome yielded by the studies is that the use of an integrated voltage regulator as a countermeasure is effective for a local attack. However, remote attacks are still effective and hence break the integrated voltage regulator countermeasure. From experimental analysis, it is observed that within the range of designs\u27 practical values, the adoption of on-package decoupling capacitors provides only a 1.3x increase in the minimum number of traces required to discover the secret key. However, the injection of noise in the IC power delivery network yields a 37x increase in the minimum number of traces to discover. Thus, increasing the number of on-package decoupling capacitors or the impedance between the local probing site and the IC power grid should not be relied on as countermeasures to power side-channel attacks, for remote attack schemes. Noise injection should be considered as it is more effective at scrambling the leaked signal to eliminate sensitive identifying information. However, the analysis and experiments carried out herein are applied to regular symmetric ciphers which are not suitable for protecting Internet of Things (IoT) devices. The protection of communications between IoT devices is of great concern because the information exchanged contains vital sensitive data. Malicious agents seek to exploit those data to extract secret information about the owners or the system. Power side channel attacks are of great concern on these devices because their power consumption unintentionally leaks information correlatable to the device\u27s secret data. Several studies have demonstrated the effectiveness of authenticated encryption with advanced data (AEAD), in protecting communications with these devices. In this research, we have proposed a comprehensive evaluation of the ten algorithm finalists of the National Institute of Standards and Technology (NIST) IoT lightweight cipher competition. The study shows that, nonetheless, some still present some residual vulnerabilities to power side channel attacks (SCA). For five ciphers, we propose an attack methodology as well as the leakage function needed to perform correlation power analysis (CPA). We assert that Ascon, Sparkle, and PHOTON-Beetle security vulnerability can generally be assessed with the security assumptions Chosen ciphertext attack and leakage in encryption only, with nonce-misuse resilience adversary (CCAmL1) and Chosen ciphertext attack and leakage in encryption only with nonce-respecting adversary (CCAL1) , respectively. However, the security vulnerability of GIFT-COFB, Grain, Romulus, and TinyJambu can be evaluated more straightforwardly with publicly available leakage models and solvers. They can also be assessed simply by increasing the number of traces collected to launch the attack

Improving access to family planning for women with disabilities in Kaduna city, Nigeria: study protocol for a pragmatic cluster-randomized controlled trial with integrated process evaluation.

BACKGROUND: Globally, women with disabilities are less likely to have access to family planning services compared to their peers without disabilities. However, evidence of effective interventions for promoting their sexual and reproductive health and rights remains limited, particularly in low- and middle-income settings. To help address disparities, an inclusive sexual and reproductive health project was developed to increase access to modern contraceptive methods and reduce unmet need for family planning for women of reproductive age with disabilities in Kaduna city, Nigeria. The project uses demand-side, supply-side and contextual interventions, with an adaptive management approach. This protocol presents a study to evaluate the project's impact. METHODS: A pragmatic cluster-randomized controlled trial design with surveys at baseline and endline will be used to evaluate interventions delivered for at least 1 year at health facility and community levels in comparison to 'standard' state provision of family planning services, in the context of state-wide and national broadcast media and advocacy. Randomization will be conducted based on the health facility catchment area, with 19 clusters in the intervention arm and 18 in the control arm. The primary outcome measure will be access to family planning. It was calculated that at least 950 women aged 18 to 49 years with disabilities (475 in each arm) will be recruited to detect a 50% increase in access compared to the control arm. For each woman with disabilities enrolled, a neighbouring woman without disabilities in the same cluster and age group will be recruited to assess whether the intervention has a specific effect amongst women with disabilities. The trial will be complemented by an integrated process evaluation. Ethical approval for the study has been given by the National Health Research Ethics Committee of Nigeria and London School of Hygiene & Tropical Medicine. DISCUSSION: Defining access to services is complex, as it is not a single variable that can be measured directly and need for family planning is subjectively defined. Consequently, we have conceptualized 'access to family planning' based on a composite of beliefs about using services if needed. TRIAL REGISTRATION: ISRCTN registry ISRCTN12671153. Retrospectively registered on 17/04/2023

Lens-free interferometric microscope for transparent materials

As health systems fight against epidemics and infectious diseases, new forms of diagnostics need to be developed in order to meet the growing demand for services, often in locations without the necessary infrastructure. An emerging solution to this problem is point of care (POC) devices since they can provide rapid diagnostics without the need for specialized personnel or complex infrastructures. In this thesis, we show the development of a POC platform for the rapid early detection of infection, in particular Sepsis, a whole-body inflammatory reaction with high mortality rates. The main components of this platform are: a lens-free interferometric microscope (LIM) and a microfluidic cartridge with a functionalized plasmonic chip for the label-free detection of biomarkers. The LIM is also able to measure the phase modulation in commercial plasmonic chips. More specifically the thesis describes: • The development of a LIM with a large field of view and depth of field showing a sensitivity of 1nm along the beam propagation axis, which allows, for instance, the measurements of ultra-thin (2nm thickness) transparent silica and protein monolayer microarrays. • The generation of periodic structured light beams, obtained using a simple configuration including the birefringent elements of the LIM. These can be applied not only to imaging and biomarker detection but also in additive manufacturing and micro-structuring of surfaces. • The phase measurement of commercial surface plasmon resonance chips for the detection of changes in the refractive index of liquids. The phase measurements provide a sensitivity for bulk refractive index changes that is about one order of magnitude larger than for intensity-based detection under similar conditions. These results show a potential enhancement of the sensitivity of standard systems used in the biomedical community. • The development of a POC device comprising the LIM as a reader of specifically designed plasmonic gold nanohole array chips. The reading of the phase signal in the LIM shows a sensitivity increased by one order of magnitude thanks to the enhanced localized surface plasmon resonance interaction. Low concentrations of proteins and bacteria (as low as a single unit) are detected in measurements that also include human samples. This platform has the potential to multiplex the signal for simultaneous detection of thousands or even millions of different biomarkers. The LIM presented in this thesis is a very sensitive and robust imaging system with a high performance level for the detection of small quantities of transparent materials, with applications in microscopy and biomedicine.A medida que los sistemas de salud combaten epidemias y enfermedades infecciosas, nuevas formas de diagnóstico deben desarrollarse para satisfacer la creciente demanda de servicios, a menudo en lugares sin la infraestructura necesaria. Una solución emergente a este problema son los dispositivos de punto de atención (POC por sus siglas en inglés) ya que pueden proporcionar un diagnóstico rápido sin la necesidad de personal especializado o infraestructura compleja. En esta tesis mostramos el desarrollo de una plataforma POC para la detección rápida y temprana de infecciones, en particular Sepsis, una reacción inflamatoria de todo el cuerpo con altas tasas de mortalidad. Los principales componentes de esta plataforma son: un microscopio interferométrico sin lentes (LIM por sus siglas en inglés) y un cartucho de microfluídica con un chip plasmónico funcionalizado para la detección de biomarcadores, libre de marcadores adicionales. El LIM es también capaz de medir la modulación de fase en chips plasmónicos comerciales. Más específicamente, la tesis describe: * El desarrollo del LIM con un gran campo de visión y profundidad de campo mostrando una sensibilidad de 1nm a lo largo del eje de propagación del haz, que permite, por ejemplo, las mediciones de microarreglos ultrafinos (grosor de 2nm) y transparentes de Sílica y de monocapas de proteína.* La generación de haces de luz estructurados periódicos, obtenidos usando una configuración simple que incluye los elementos birrefringentes del LIM. Estos pueden ser aplicados no sólo a la detección de imágenes y biomarcadores, sino también a la fabricación aditiva y microestructuración de superficies. * La medición de fase en chips comerciales por resonancia de plasmón superficial para la detección de cambios en el índice de refracción de líquidos. Las mediciones de fase proporcionan una sensibilidad para cambios de índice de refracción en bulto que es aproximadamente un orden de magnitud mayor que para la detección basada en la intensidad con condiciones similares. Estos resultados muestran una potencial mejora de la sensibilidad de los sistemas estándar utilizados en la comunidad biomédica. * El desarrollo de un dispositivo POC que comprende el LIM como lector de chips plasmónicos de oro con arreglos de nano-agujeros específicamente diseñados. La lectura de la señal de fase en el LIM muestra un aumento de un orden de magnitud en la sensibilidad gracias a la interacción mejorada por la resonancia de plasmón superficial localizado. Bajas concentraciones de proteínas y bacterias (tan bajas como una sola bacteria) se detectan en mediciones que también incluyen muestras humanas. Esta plataforma tiene el potencial de multiplexar la señal para la detección simultánea de miles o incluso millones de biomarcadores diferentes. El LIM presentado en esta tesis es un sistema de imagen muy sensible y robusto con un alto nivel de rendimiento para la detección de pequeñas cantidades de materiales transparentes, con aplicaciones en microscopía y biomedicina.Postprint (published version