Programmable photonics : an opportunity for an accessible large-volume PIC ecosystem

We look at the opportunities presented by the new concepts of generic programmable photonic integrated circuits (PIC) to deploy photonics on a larger scale. Programmable PICs consist of waveguide meshes of tunable couplers and phase shifters that can be reconfigured in software to define diverse functions and arbitrary connectivity between the input and output ports. Off-the-shelf programmable PICs can dramatically shorten the development time and deployment costs of new photonic products, as they bypass the design-fabrication cycle of a custom PIC. These chips, which actually consist of an entire technology stack of photonics, electronics packaging and software, can potentially be manufactured cheaper and in larger volumes than application-specific PICs. We look into the technology requirements of these generic programmable PICs and discuss the economy of scale. Finally, we make a qualitative analysis of the possible application spaces where generic programmable PICs can play an enabling role, especially to companies who do not have an in-depth background in PIC technology

A Microfluidic-Integrated SIW Lab-on-Substrate Sensor for Microliter Liquid Characterization

A novel microfluidic-integrated microwave sensor with potential application in microliter-volume biological/biomedical liquid sample characterization and quantification is presented in this paper. The sensor is designed based on the resonance method, providing the best sensing accuracy, and implemented by using a substrate-integrated-waveguide (SIW) structure combining with a rectangular slot antenna operating at 10 GHz. The device can perform accurate characterization of various liquid materials from very low to high loss, demonstrated by measurement of deionized (DI) water and methanol liquid mixtures. The measured relative permittivity, which is the real part of complex permittivity, ranges from 8.58 to 66.12, which is simply limited by the choice of test materials available in our laboratory, not any other technical considerations of the sensor. The fabricated sensor prototype requires a very small liquid volume of less than 7 µl, while still offering an overall accuracy of better than 3 %, as compared to the commercial and other published works. Key advantages of the proposed sensor are that it combines 1.) a very low-profile planar and miniaturized structure sensing microliter liquid volume; 2.) ease of design and fabrication, which makes it cost-effective to manufacture and 3.) noninvasive and contactless measurements. Moreover, since the microfluidic subsystem can potentially be detached from the SIW microwave sensor and, afterward, replaced by a new microfluidic component, the sensor can be reused with no life-cycle limitation and without degrading any figure of merit

Overcoming the Challenges for Multichip Integration: A Wireless Interconnect Approach

The physical limitations in the area, power density, and yield restrict the scalability of the single-chip multicore system to a relatively small number of cores. Instead of having a large chip, aggregating multiple smaller chips can overcome these physical limitations. Combining multiple dies can be done either by stacking vertically or by placing side-by-side on the same substrate within a single package. However, in order to be widely accepted, both multichip integration techniques need to overcome significant challenges. In the horizontally integrated multichip system, traditional inter-chip I/O does not scale well with technology scaling due to limitations of the pitch. Moreover, to transfer data between cores or memory components from one chip to another, state-of-the-art inter-chip communication over wireline channels require data signals to travel from internal nets to the peripheral I/O ports and then get routed over the inter-chip channels to the I/O port of the destination chip. Following this, the data is finally routed from the I/O to internal nets of the target chip over a wireline interconnect fabric. This multi-hop communication increases energy consumption while decreasing data bandwidth in a multichip system. On the other hand, in vertically integrated multichip system, the high power density resulting from the placement of computational components on top of each other aggravates the thermal issues of the chip leading to degraded performance and reduced reliability. Liquid cooling through microfluidic channels can provide cooling capabilities required for effective management of chip temperatures in vertical integration. However, to reduce the mechanical stresses and at the same time, to ensure temperature uniformity and adequate cooling competencies, the height and width of the microchannels need to be increased. This limits the area available to route Through-Silicon-Vias (TSVs) across the cooling layers and make the co-existence and co-design of TSVs and microchannels extreamly challenging. Research in recent years has demonstrated that on-chip and off-chip wireless interconnects are capable of establishing radio communications within as well as between multiple chips. The primary goal of this dissertation is to propose design principals targeting both horizontally and vertically integrated multichip system to provide high bandwidth, low latency, and energy efficient data communication by utilizing mm-wave wireless interconnects. The proposed solution has two parts: the first part proposes design methodology of a seamless hybrid wired and wireless interconnection network for the horizontally integrated multichip system to enable direct chip-to-chip communication between internal cores. Whereas the second part proposes a Wireless Network-on-Chip (WiNoC) architecture for the vertically integrated multichip system to realize data communication across interlayer microfluidic coolers eliminating the need to place and route signal TSVs through the cooling layers. The integration of wireless interconnect will significantly reduce the complexity of the co-design of TSV based interconnects and microchannel based interlayer cooling. Finally, this dissertation presents a combined trade-off evaluation of such wireless integration system in both horizontal and vertical sense and provides future directions for the design of the multichip system

Feasibility of an Electro-Optic Link for Bondpad-less CMOS Lab-on-Chips

This paper explores the feasibility of developing CMOS-based lab-on-chips to analyse the properties of a fluid, without the need for bond wires. Both inductive and electro-optical schemes are suggested as possible solutions. Specifically, this paper details a novel approach in achieving electro-optical modulation in unmodified, commercially-available CMOS technology. By exploiting the plasma dispersion effect, it is shown how mid-infrared light can be modulated using parasitic structures designed in a CMOS integrated circuit. Both the fundamental theory and practical realisation are supported with measured data from an experimental setup.Accepted versio

Development of a portable microfluidic system for monitoring ions river water

Nowadays, there is a growing demand for predictive models that are capable of predicting future trends in water quality which is constantly being affected by environmental changes and industrialisation. The presence of various nutrient contaminants in surface water poses a serious threat to human health. The initial step for the development of this predictive model is to have an in situ monitoring system that provides high frequency screening and monitoring of nutrients in surface water. At present, the conventional in situ monitoring systems available are too cumbersome, expensive and laborious.The main aim of this project was to develop a portable and automated miniaturised total analytical system (μTAS) monitoring system that could provide in situ river water nutrient measurements over a wide range of analytes such as cations (Na⁺, K⁺, Ca²⁺, Mg²⁺, NH₄⁺) and anions (Cl⁻, NO₂⁻, NO₃⁻, SO₄²⁻, PO₄³⁻). The contribution of this work to the overall project was to integrate sample pre-treatment procedures on-chip to allow direct and reproducible analysis of real samples and to investigate the possibility of fabricating an anion exchange column through immobilisation with different ion exchangers using a self-fabricated silica monolithic column.A combination of on-chip sample filtration and sample introduction system was investigated using potassium silicate frit and electrophoretic injection to selectively extract the analytes prior to introduction into the microfluidic system. The frits were optimised and proven to possess high mechanical stability and flow resistance against hydrodynamic and hydrostatic flows. Sodium ions were successfully migrated into the microfluidic system through the frit by electrophoretic flow with ion migration efficiency of 26%. Despite the low ion migration efficiency obtained, the results demonstrated the potential of coupling the sample filtration frit with sample introduction system in a microfluidic chip to prevent passage of large particulates into the system causing system blockage.Isotachophoresis (ITP) is one of the most widely reported on-chip sample pre-concentration techniques but due to the complexity of the ternary buffer systems in ITP, introduction of these buffers in an appropriate and cost-effective approach would be difficult. An investigation of a simple miniaturised gel supported ITP system was conducted where all the necessary buffers were encapsulated in agarose gel and pre-loaded onto a microfluidic chip. A proof of principle experiment was conducted in a “goal post” system and sodium ions were shown to be able to migrate through the gel encapsulated buffer system. However, implementation of the experiment in the microfluidic chip was unsuccessful due to occurrence of gel deformation.Preliminary investigation of fabricating an anion exchange column using a self-fabricated silica monolithic column was conducted based on solid phase extraction (SPE). Two different ion exchangers, chitosan and lysine, were investigated due to their high content of amino groups. Lysine was shown to be successfully immobilised onto the silica surface and to have reasonable extraction efficiency of 62% in extracting nitrate ions. Chitosan, however, failed to show any positive result, this may be due to an unsuccessful functionalisation procedure or poor pre-conditioning of the column.The findings obtained in this thesis contributed to the main aim of the project by demonstrating the potential of coupling a sample filtration frit with a sample introduction system which allowed the in situ μTAS monitoring system to extract the analytes from the sample matrix prior to introduction into the system. This is crucial as these real samples contain large particulates that can cause serious operational problems such as system blockage. In addition, due to the high cost of commercial silica monolithic exchange column, the work presented indicated the potential for self-fabricating the ion exchange silica monolithic column, which is more cost-effective

3D Integration: Another Dimension Toward Hardware Security

We review threats and selected schemes concerning hardware security at design and manufacturing time as well as at runtime. We find that 3D integration can serve well to enhance the resilience of different hardware security schemes, but it also requires thoughtful use of the options provided by the umbrella term of 3D integration. Toward enforcing security at runtime, we envision secure 2.5D system-level integration of untrusted chips and "all around" shielding for 3D ICs.Comment: IEEE IOLTS 201