CMOS-based sensor array chips provide new and attractive features as compared to todays standard tools for medical, diagnostic, and biotechnical applications. Examples for molecule- and cell-based approaches and related circuit design issues are discussed.
This paper presents the design and analysis of a wearable CMOS biosensor with three different designs of energy-resolution scalable time-based resistance to digital converters (RDC), targeted towards either minimizing the energy/conversion step or ma
ximizing bit-resolution. The implemented RDCs consist of a 3-stage differential ring oscillator which is current starved with the resistive sensor, a differential to single ended amplifier, an off-chip counter and serial interface. The first design RDC included the basic structure of time-based RDC and targeted low energy/conversion step. The second design RDC aimed to improve the rms jitter/phase noise of the oscillator with help of speed-up latches, to achieve higher bit-resolution as compared to the first design RDC. The third design RDC reduced the power consumption by scaling the technology with the improved phase-noise design, achieving 1-bit better resolution as that of the second design RDC. Using a time-based implementation, the RDCs exhibit energy-resolution scalablity, and consume 861nW with 18-bit resolution in design 1 in TSMC 0.35um technology. Design 2 and 3 consume 19.1uW with 20-bit resolution using TSMC 0.35um, and 17.6uW with 20-bit resolutions using TSMC 0.18um, respectively (both with 10ms read-time, repeated every second). With 30ms read-time, design 3 achieves 21-bit resolution, which is the highest resolution reported for a time-based ADC. The 0.35um time-based RDC is the lowest-power time-based ADC reported, while the 0.18um time-based RDC with speed-up latch offers the highest resolution. The active chip-area for all 3-designs are less than 1.1 mm^2.
A robust power gating design using Graphene Nano-Ribbon Field Effect Transistors (GNRFET) is proposed using 16nm technology. The Power Gating (PG) structure is composed of GNRFET as a power switch and MOS power gated module. The proposed structure re
solves the main drawbacks of the traditional PG design from the point of view increasing the propagation delay and wake-up time in low voltage regions. GNRFET/MOSFET Conjunction (GMC) is employed to build various structures of PG, GMCPG-SS and GMCPG-NS. In addition to exploiting it to build two multi-mode PG structures. Circuit analysis for CMOS power gated logic modules ISCAS85 benchmark of 16nm technology is used to evaluate the performance of the proposed GNR power switch is compared to the traditional MOS one. Leakage power, wake-up time and power delay product are used as performance circuit parameters for the evaluation.
Viral infections are among the main reasons for serious pandemics and contagious infections; hence, they cause thousands of fatalities and economic losses annually. In the case of COVID-19, world economies have shut down for months, and physical dist
ancing along with drastic changes in the social behavior of many humans has generated many issues for all countries. Thus, a rapid, low-cost, and sensitive viral detection method is critical to upgrade the living standards of humans while exploiting biomedicine, environmental science, bioresearch, and biosecurity. The emergence of various carbon-based nanomaterials such as carbon nanotubes, graphene, and carbon nanoparticles provided a great possibility for researchers to develop a new and wide variety of biosensors. In particular, graphene has become a promising tool for biosensor fabrication owing to its many interesting properties, such as its exceptional conductivity, ultrahigh electron mobility, and excellent thermal conductivity. This paper provides an overall perspective of graphene-based biosensors and a critical review of the recent advances in graphene-based biosensors that are used to detect different types of viruses, such as Ebola, Zika, and influenza.
We experimentally demonstrate broadband waveguide crossing arrays showing ultra low loss down to $0.04,$dB/crossing ($0.9%$), matching theory, and crosstalk suppression over $35,$dB, in a CMOS-compatible geometry. The principle of operation is the ta
ilored excitation of a low-loss spatial Bloch wave formed by matching the periodicity of the crossing array to the difference in propagation constants of the 1$^text{st}$- and 3$^text{rd}$-order TE-like modes of a multimode silicon waveguide. Radiative scattering at the crossing points acts like a periodic imaginary-permittivity perturbation that couples two supermodes, which results in imaginary (radiative) propagation-constant splitting and gives rise to a low-loss, unidirectional breathing Bloch wave. This type of crossing array provides a robust implementation of a key component enabling dense photonic integration.
In the context of natural-based wastewater treatment technologies (such as constructed wetlands - CW) the use of a low-cost, continuous-like biosensor tool for the assessment of operational conditions is of key importance for plant management optimiz
ation. The objective of the present study was to assess the potential use of constructed wetland microbial fuel cells (CW-MFC) as a domestic wastewater COD assessment tool. For the purpose of this work four lab-scale CW-MFCs were set up and fed with pre-settled domestic wastewater at different COD concentrations. Under laboratory conditions two different anodic materials were tested (graphite rods and gravel). Furthermore, a pilot-plant based experiment was also conducted to confirm the findings previously recorded for lab-scale experiments. Results showed that in spite of the low coulombic efficiencies recorded, either gravel or graphite-based anodes were suitable for the purposes of domestic wastewater COD assessment. Significant linear relationships could be established between inlet COD concentrations and CW-MFC Ecell whenever contact time was above 10 hours. Results also showed that the accuracy of the CW-MFC was greatly compromised after several weeks of operation. Pilot experiments showed that CW-MFC presents a good bio-indication response between week 3 and 7 of operation (equivalent to an accumulated organic loading between 100 and 200 g COD/m2, respectively). Main conclusion of this work is that of CW-MFC could be used as an alarm-tool for qualitative continuous influent water quality assessment rather than a precise COD assessment tool due to a loss of precision after several weeks of operation.