We show that the Raman scattering technique can give complete structural information for one-dimensional systems, such as carbon nanotubes. Resonant confocal micro-Raman spectroscopy of an (n,m) individual single-wall nanotube makes it possible to assign its chirality uniquely by measuring one radial breathing mode frequency omega(RBM) and using the theory of resonant transitions. A unique chirality assignment can be made for both metallic and semiconducting nanotubes of diameter d(t), using the parameters gamma(0) = 2.9 eV and omega(RBM) = 248/d(t). For example, the strong RBM intensity observed at 156 cm(-1) for 785 nm laser excitation is assigned to the (13,10) metallic chiral nanotube on a Si/SiO2 surface.

Structural (n,m) determination of isolated single wall carbon nanotubes by resonant Raman scattering

More than a decade of research in the field of thermal, motion, vibration and electromagnetic radiation energy harvesting has yielded increasing power output and smaller embodiments. Power management circuits for rectification and DC-DC conversion are becoming able to efficiently convert the power from these energy harvesters. This paper summarizes recent energy harvesting results and their power management circuits.

Micropower energy harvesting

https://www.tandfonline.com/doi/pdf/10.1080/14686996.2018.1530938

Thermoelectric materials and applications for energy harvesting power generation

The photoluminescence signals of a graphene/MoS2 heterostructural stacking film are sensitive to environmental charges, which allows the single-base sequence-selective detection of DNA hybridization with sensitivity to the level of aM.

https://ir.nctu.edu.tw:443/bitstream/11536/24868/1/000339661600011.pdf

Graphene/MoS2 Heterostructures for Ultrasensitive Detection of DNA Hybridisation

Silicon nanowire biosensor and its applications in disease diagnostics: A review

We herein report the design of a novel semiconducting silicon nanowire field-effect transistor (SiNW-FET) biosensor array for ultrasensitive label-free and real-time detection of nucleic acids. Highly responsive SiNWs with narrow sizes and high surface-to-volume-ratios were "top-down" fabricated with a complementary metal oxide semiconductor compatible anisotropic self-stop etching technique. When SiNWs were covalently modified with DNA probes, the nanosensor showed highly sensitive concentration-dependent conductance change in response to specific target DNA sequences. This SiNW-FET nanosensor revealed ultrahigh sensitivity for rapid and reliable detection of 1 fM of target DNA and high specificity single-nucleotide polymorphism discrimination. As a proof-of-concept for multiplex detection with this small-size and mass producible sensor array, we demonstrated simultaneous selective detection of two pathogenic strain virus DNA sequences (H1N1 and H5N1) of avian influenza.

Silicon-nanowire-based CMOS-compatible field-effect transistor nanosensors for ultrasensitive electrical detection of nucleic acids.

Silicon nanowire (SiNW) field effect transistors (FETs) have emerged as powerful sensors for ultrasensitive, direct electrical readout, and label-free biological/chemical detection. The sensing mechanism of SiNW-FET can be understood in terms of the change in charge density at the SiNW surface after hybridization. So far, there have been limited systematic studies on fundamental factors related to device sensitivity to further make clear the overall effect on sensing sensitivity. Here, we present an analytical result for our triangle cross-section wire for predicting the sensitivity of nanowire surface-charge sensors. It was confirmed through sensing experiments that the back-gated SiNW-FET sensor had the highest percentage current response in the subthreshold regime and the sensor performance could be optimized in low buffer ionic strength and at moderate probe concentration. The optimized SiNW-FET nanosensor revealed ultrahigh sensitivity for rapid and reliable detection of target DNA with a detection limit of 0.1 fM and high specificity for single-nucleotide polymorphism discrimination. In our work, enhanced sensing of biological species by optimization of operating parameters and fundamental understanding for SiNW FET detection limit was obtained.

Enhanced sensing of nucleic acids with silicon nanowire field effect transistor biosensors.

In this paper, a reliable micro-hotplate with low power consumption is demonstrated by optimizing its structure and materials. Its power consumption is successfully decreased by adopting a structure with two high length-to-width slender beams. High reliability is achieved by improving its mechanical strength and long-term stability. A stacked membrane with residual stress controlled and corner compensations improve its mechanical strength. Pt heater element and Al2O3 adhesive layer deposited by atomic layer deposition (ALD) improve its long-term stability. Test results indicate that the micro-hotplate consumes only 18 mW when heated up to 400°C with a heating response time<;5 ms and cooling response time<;3 ms. It can sustain at least 842400 circles pulsed-mode operation with ultra-low resistance drift and can continuously work stably at around 450°C for at least 500 h.

Development of a Reliable Micro-Hotplate With Low Power Consumption

This paper presents a CMOS MEMS-based thermoelectric energy generator (TEG) device with an efficient heat dissipation path. For present CMOS MEMS-based thermoelectric generator devices, the output performance is greatly limited by the high thermal-contact resistance in the system. For the device proposed in the work, the silicon substrate is etched into two comb-shaped blocks thermally isolated from each other, which form the hot and cold sides. Thin-film-based thermal legs are densely located between the two blocks along the winding split line. Low internal thermal-contact resistance is achieved with the symmetrical thermal structure. When the TEG device is embedded between the heat source and heat sink, the heat loss can be well controlled with flat thermal-contact pads of the device. For a full device with 900 n/p-polysilicon thermocouples, the measured open-circuit voltage reaches as high as 146 mV K−1, and the power factor reaches almost five times higher value compared to the previously reported results. A test system integrated with a single device presents an open-circuit voltage of 110 mV K−1 when forcibly cooled by a Peltier cooler, or 26 mV K−1 when cooled by ambient air.

https://iopscience.iop.org/article/10.1088/0960-1317/22/10/105011/pdf

Xiuli Gao

Papers

Silicon-nanowire-based CMOS-compatible field-effect transistor nanosensors for ultrasensitive electrical detection of nucleic acids.

Enhanced sensing of nucleic acids with silicon nanowire field effect transistor biosensors.

Development of a Reliable Micro-Hotplate With Low Power Consumption

CMOS MEMS-based thermoelectric generator with an efficient heat dissipation path

Ultra-sensitive nucleic acids detection with electrical nanosensors based on CMOS-compatible silicon nanowire field-effect transistors.