A nanostructured Fabry-Perot interferometer for label-free biodetection

A polymer nanostructured Fabry-Perot interferometer (FPI) based biosensor has been developed, fabricated, and tested. Different from a conventional FPI, this nanostructured FPI has a layer of Au-coated nanopores inside its cavity. The Au-coated nanostructure layer offers significant enhancement of optical transducing signals due to the localized surface Plasmon resonance (L-SPR) effect. Compared to a traditional FPI for label-free biosensing applications, the polymer nanostructured FPI based biosensor offers increased sensing surface area, extended penetration depth of the excitation light, and amplification of optical transducing signals. Using a nanostructured FPI, measurements taken had great improvements in free spectral range (FSR), finesse, and contrast of optical transducing signals over a traditional FPI without any device performance optimization. Several chemicals have been evaluated using the prototype device. Fourier Transform has been performed on the measured optical signals to facilitate the analysis of the transducing signals. Control experiments incubating immunoglobulin G (IgG) on a gold surface confirmed the small affinity of IgG to the Au-coated sensing surface. Then, using fluorescent images, shifts of interference fringes for IgG and BSA interaction were indirectly confirmed. Using this technical platform, the immobilization of capture proteins (Protein A) on the nanostructure layer and their binding with IgG was monitored in real time, resulting in the direct observation of the shift in interference fringes of the optical transducing signals. The results showed that the detection of limit (DOL) for this kind of biosensor should be lower than 10 pg/mL, which is approximately 55 fIVI of IgG, for IgG-Protein A binding. Control experiments were performed to confirm that the biodetection is only specific to Protein A and IgG recognition. After the proof-of-concept demonstration for IgG-Protein A binding, the ultrasensitive label-free detection of a cancer biomarker free prostate specific antigen (fPSA) using this kind of nanostructured FPI was carried out. Experiments found that the DOL of the fabricated nanostructured FPI microchip for f-PSA is about 5 pg/mL and the upper detection range for f-PSA can be dynamically changed by varying the amount of mAb immobilized on the sensing surface. Control experiments have also demonstrated that the immunoassay protocol used shows excellent specificity and selectivity, suggesting great potential to detect cancer biomarkers at trace levels in biofluids. Given its nature of low cost, simple operation, and batch fabrication capability, the nanostructured FPI microchip based platform could provide an ideal technical tool for point-of-care diagnostic applications and anti-cancer drug screening and discovery

Ideal magnetic dipole scattering

We introduce the concept of tunable ideal magnetic dipole scattering, where a nonmagnetic nanoparticle scatters lights as a pure magnetic dipole. High refractive index subwavelength nanoparticles usually support both electric and magnetic dipole responses. Thus, to achieve ideal magnetic dipole scattering one has to suppress the electric dipole response. Such a possibility was recently demonstrated for the so-called anapole mode, which is associated with zero electric dipole scattering. By overlapping magnetic dipole resonance with the anapole mode we achieve ideal magnetic dipole scattering in the far-field with tunable high scattering resonances in near infrared spectrum. We demonstrate that such condition can be realized for two subwavelength geometries. One of them is core-shell nanosphere consisting of Au core and silicon shell. It can be also achieved in other geometries, including nanodisks, which are compatible with current nanofabrication technology.Comment: Submit for publication, comments are welcom

Softmax Acceleration with Adaptive Numeric Format for both Training and Inference

The attention mechanism is a pivotal element within the Transformer architecture, making a substantial contribution to its exceptional performance. Within this attention mechanism, Softmax is an imperative component that enables the model to assess the degree of correlation between various segments of the input. Yet, prior research has shown that Softmax operations can significantly increase processing latency and energy consumption in the Transformer network due to their internal nonlinear operations and data dependencies. In this work, we proposed~\textit{Hyft}, a hardware efficient floating point Softmax accelerator for both training and inference. Hyft aims to reduce the implementation cost of different nonlinear arithmetic operations by adaptively converting intermediate results into the most suitable numeric format for each specific operation, leading to reconfigurable accelerator with hybrid numeric format. The evaluation results highlight that Hyft achieves a remarkable $15\times$ reduction in hardware resource utilization and a $20 \times$ reduction in processing latency, all while maintaining a negligible impact on Transformer accuracy

Non-coherent detection for ultraviolet communications with inter-symbol interference

Ultraviolet communication (UVC) serves as a promising supplement to share the responsibility for the overloads in conventional wireless communication systems. One challenge for UVC lies in inter-symbol-interference (ISI), which combined with the ambient noise, contaminates the received signals and thereby deteriorates the communication accuracy. Existing coherent signal detection schemes (e.g. maximum likelihood sequence detection, MLSD) require channel state information (CSI) to compensate the channel ISI effect, thereby falling into either a long overhead and large computational complexity, or poor CSI acquisition that further hinders the detection performance. Non-coherent schemes for UVC, although capable of reducing the complexity, cannot provide high detection accuracy in the face of ISI. In this work, we propose a novel non-coherent paradigm via the exploration of the UV signal features that are insensitive to the ISI. By optimally weighting and combining the extracted features to minimize the bit error rate (BER), the optimally-weighted non-coherent detection (OWNCD) is proposed, which converts the signal detection with ISI into a binary detection framework with a heuristic decision threshold. As such, the proposed OWNCD avoids the complex CSI estimation and guarantees the detection accuracy. Compared to the state-of-the-art MLSD in the cases of static and time-varying CSI, the proposed OWNCD can gain ∼1 dB and 8 dB in signal-to-noise-ratio (SNR) at the 7% overhead FEC limit (BER of 4.5×10 −3 , respectively, and can also reduce the computational complexity by 4 order of magnitud

Identification of functional regions of streptococcus agalactiae CAMP factor

Streptococcus agalactiae CAMP factor is a protein exotoxin that contains 226 amino acid residues and forms oligomeric pores on susceptible cell membranes and liposomes. In this study, fragments of CAMP factor were created and recombinantly expressed to identify functional domains that are involved in membrane binding, oligomerization, and membrane insertion. Altogether, six truncated forms of CAMP factor were created and assayed. CAMP1-113, CAMP1-170, CAMP57-226, and CAMP171-226 showed different levels of hemolytic activity. CAMP1-56 and CAMP114-226 did not show hemolytic activity or oligomerization ability, but showed binding ability. CAMP114-226 inhibited the hemolytic activity of wild-type CAMP factor, most likely through ‘one-sided’ oligomerization. From the comparison of these fragments, it emerges that the region between residues 57 and 113 plays a crucial role in oligomerization and membrane insertion. The high binding efficiency of CAMP114-226 suggests this region has great responsibility on membrane binding. The hemolytically inactive fragments showed higher binding efficiency than some of the active fragments. For the hemolytic fragments, higher binding efficiency gave stronger hemolysis. These findings support that CAMP factor has different functional regions for pore-formation