Comb-like Electrodes Research Articles

The emergence of MnFe2O4 nanosphere-based humidity sensor: a methodical investigation by scanning Kelvin probe and its deployment in multitudinous applications

In this study, the ambient temperature humidity sensing properties of solvothermally synthesized MnFe2O4 (MFO) nanospheres on interconnected comb-like silver electrodes were studied systematically.

Enhanced performance of GaAs-based betavoltaic batteries by using AlGaAs hole/electron transport layers

The GaAs-based betavoltaic batteries with source were demonstrated, in which the AlGaAs hole/electron transport layers were introduced to enhance the transport and collection of radiation-induced carriers. The Monte Carlo codes and COMSOL Multiphysics were combined to predict the output performance of batteries and optimize the structure parameters of energy converter. And the optimized GaAs-based battery with a 6 mCi cm−2 source was expected to achieve a short-circuit current density (J sc ) of 85.6 nA cm−2, an open-circuit voltage (V oc ) of 0.67 V and a maximum output power density (P m ) of 43.3 nW cm−2. Then the GaAs/AlGaAs films were grown by metal organic chemical vapor deposition, and the comb-like electrodes were designed to reduce the absorption loss of beta particles in the p-plane electrode. The photoluminescence and x-ray diffraction were carried out to characterize the growth quality of epitaxial materials. The experimental results showed that the largest J sc of 9.3 nA cm−2, V oc of 55 mV and P m of 143.9 pW cm−2 can be achieved on the 2-busbar electrode battery. And the temperature dependence tests showed that when the temperature decreased to 233.15 K, the V oc and P m increased to 208 mV and 570.5 pW cm−2, respectively. Further improvements in fabrication process are needed to reduce the gap between experiment and prediction. In addition, the optimized structure of energy converter suggests the directions for enhancing the performance of betavoltaic batteries.

着陸レーザーレーダ用2次元MEMS光スキャナ

We present the design, fabrication, and demonstration of a two-dimensional MEMS (microelectromechanical systems) optical scanner for a compact laser radar for a spacecraft landing on a planet. Electrostatic force caused by the voltages applied to the comb-like micro electrodes is adopted as an operation principle that is inherently robust to the harsh environment in space. Optical scan angles of 10º × 15º is obtained with drive voltages of 150V.

Effect of Front Electrode on the Structure and Performances of Ga x In1-x As y Sb1-y Thermophotovoltaic Cell

We have theoretically investigated the effect of front electrode on the structure and performances of Ga x In $_{1-{x}}$ As y Sb $_{1-{y}}$ thermophotovoltaic (TPV) cells. By sampling a comb-like electrode, it is clearly demonstrated here that the optimum grid separation ${d}_{G}$ depending on the cell bandgap yields a quadratic function for a given spectrum illumination, while the desired coefficients are strongly temperature-dependent and can be well modeled by an exponential decay expression. Comparing with previous report with constant grid separation, the denser front electrode promises an inferior cell efficiency, but the similar phenomenological method can be still applicable to predict the structure and performance of Ga x In $_{1-{x}}$ As y Sb $_{1-{y}}$ TPV cells for a given operation environment.

Formation mechanism of ferroelectric poly (vinylidene fluoride-trifluoroethylene) copolymers with in-plane dipole alignment under low electric field from melt and its SPR based pyroelectric sensor

P(VDF/TrFE) thin films were annealed under a low electric field using microgapped comb-like electrodes (IDT structure), and their structures and pyroelectric properties were investigated. In-plane dipole alignment of P(VDF/TrFE) was achieved by applying a low electric field (7.7 MV m−1), and the I phase crystal structure with in-plane dipole alignment was transformed following nucleation of the III phase structure. Despite the absence of a Fabry–Perot-type infrared absorption structure, the P(VDF/TrFE) thin films, which were continuously subjected to a low electric field from the melting point to para-ferroelectric phase transition temperature, exhibited a large pyroelectric signal. The voltage sensitivity was 242 V W−1, which is much higher than that of the sandwich type sensor equipped with a Fabry–Perot-type infrared absorption structure on Si substrates (72 V W−1). The improved sensitivity could be attributed to the suppression of the injected charges under the application of a low electric field and the enhancement of the infrared absorption and infrared-to-thermal conversion owing to the surface plasmon resonance on the microgapped IDT structure.

Fabrication of p-Type Co₃O₄ Nanofiber Sensors for Ultra-Low H₂S Gas Detection at Low Temperature.

In the current work, we report the on-chip fabrication of a low-temperature H₂S sensor based on p-type Co₃O₄ nanofibers (NFs) using the electrospinning method. The FESEM images show the typical spider-net like morphologies of synthesized Co₃O₄ NFs with an average diameter of 90 nm formed on the comb-like electrodes. The EDX data indicate the presence of Co and O elements in the NFs. The XRD analysis results confirm the formation of single-phase cubic spinel nanocrystalline structures (Fd3 m) for the synthesized Co₃O₄ NFs. The Raman results are in agreement with the XRD data through the presence of five typical vibration modes of the nanocrystalline Co₃O₄. The gas sensing properties of the fabricated Co₃O₄ NF sensors are tested to 1 ppm H₂S within a temperature range of 150 °C to 450 °C. The results indicate a highest sensor response to 1 ppm H₂S with the gas response of aproximately 2.1 times and the gas response/recovery times of 75 s/258 s at a low temperature of 250 °C. The fabricated sensor also demonstrates good selectivity and a low detection limit of 18 ppb. The overall results suggest a simple and effective fabrication process for the p-type Co₃O₄ NF sensor for practical applications in detecting H₂S gas at low temperature.

In-situ EIS study on the initial corrosion evolution behavior of SAC305 solder alloy covered with NaCl solution

The corrosion performance of SAC305 solder joints is closely related to the working efficiency and life-span of electronic devices. Available studies on corrosion of SAC305 solder have seldom concentrated on its initial corrosion evolution behavior, which is critical in understanding its corrosion behavior in the long run. In this work, comb-like electrodes have been designed for in-situ EIS measurements to investigate the initial corrosion evolution process of SAC305 solder covered with 3.5 wt.% NaCl solution, and Raman, XRD, SEM and EPMA have also been employed to characterize the formed corrosion product layer. The results indicate that the initial corrosion evolution behavior of SAC305 solder mainly involves four stages, i.e. the corrosion degradation of the pre-existing SnO2 protective film in a short duration in contact with NaCl solution, the anodically dissolved Sn2+ undergoes hydrolysis under the effect of Cl− in electrolyte to form stannous hydroxychloride intermediates of various structures, the formation of Sn3O2(OH)2 from stannous hydroxychloride intermediates after Cl− releasing, and finally the formation of nano-SnO2 particles from Sn3O2(OH)2 after steps of dehydration and oxidation. Meanwhile, the acidified NaCl electrolyte can make the formed SnO2 slightly dissolved and favors the formation of SnCl4·4H2O crystals. These findings clearly demonstrate the initial corrosion evolution behavior and corrosion product formation mechanism of SAC305 solder, and are expected to provide potential guidelines on maintenance of microelectronic devices in marine atmosphere.

Microstructure induced galvanic corrosion evolution of SAC305 solder alloys in simulated marine atmosphere

Motivated by the increasing use of Sn-3.0Ag-0.5Cu (SAC305) solder in electronics worked in marine atmospheric environment and the uneven distribution of Ag3Sn and Cu6Sn5 intermetallic compounds (IMCs) in β-Sn matrix, comb-like electrodes have been designed for in-situ EIS measurements to study the microstructure induced galvanic corrosion evolution of SAC305 solder in simulated marine atmosphere with high-temperature and high-humidity. Results indicate that in-situ EIS measurement by comb-like electrodes is an effective method for corrosion evolution behavior study of SAC305 solder. Besides, the galvanic effect between Ag3Sn IMCs and β-Sn matrix can aggravate the corrosion of both as-received and furnace-cooled SAC305 solder as the exposure time proceeds in spite of the presence of corrosion product layer. Pitting corrosion can be preferentially found on furnace-cooled SAC305 with larger Ag3Sn grain size. Moreover, the generated inner stress during phases transformation process with Sn3O(OH)2Cl2 as an intermediate and the possible hydrogen evolution at local acidified sites are supposed to be responsible for the loose, porous, cracked, and non-adherent corrosion product layer. These findings clearly demonstrate the corrosion acceleration behavior and mechanism of SAC305 solder, and provide potential guidelines on maintenance of microelectronic devices for safe operation and longer in-service duration.

Characteristics of an infrared sensor formed with a few molecular layers of vinylidene fluoride oligomers with in situ poling during vacuum evaporation

Perpendicularly oriented vinylidene fluoride oligomer thin films with six molecular layers were poled during vacuum evaporation (in situ poling) using a micro-gapped comb-like electrode, and their pyroelectric characteristics were investigated. The extent of polarization achieved with in situ poling performed by applying a low electric field (7.7 MV m−1) is the same as that achieved by conventional post-poling with the application of a high electric field (>100 MV m−1). Despite using a film with a few molecular layers, the in situ poled sensor showed pyroelectric response without the use of an infrared ray absorption layer; voltage sensitivity of 198 V W−1 was obtained, which is much higher than that of the post-poled sensor (∼16 V W−1). The improvement in sensitivity is attributed to the amount of charge injected during the poling treatment.

Study on Phonon Amplification of Neganov–Luke Light Detectors

We report progress on the development of a light detector with Neganov–Luke (NL) phonon amplification. Double comb-like electrodes were fabricated on an intrinsic Si wafer to apply an electric field. A metallic magnetic calorimeter was used for a sensitive measurement of the temperature increase originating from the light absorption in the wafer and NL phonon amplification. The NL light detector was applied to the simultaneous detection of heat and light signals from a $$\hbox {ZnWO}_4$$ scintillating crystal. Clear amplification of the light signals was obtained for various voltages applied to the electrodes, while no change in the heat signals was observed. The voltage dependence of the measured gain was investigated for a few efficiency parameters, such as the saturation voltage required to suppress the recombination of electron-hole pairs and the heat generation efficiency of the NL effect.

Monitoring of atmospheric corrosion and dewing process by interlacing copper electrode sensor

A novel dewing sensor consisting of two interlacing (comb-like) copper electrodes was fabricated by photolithography to monitor the formation and evaporation process of thin electrolyte layer (TEL), as well as atmospheric corrosion of copper during wetting-drying and high-low temperature cyclic tests. Thanks to the ultra-narrow space between the comb-like electrodes, the sensor can probe earlier dew condensation on Cu even at low relative humidity. Moreover, the thickness of TEL can be easily calculated based on high-frequency impedance during the drying process of TEL.

Room temperature ammonia gas sensor based on Au/graphene nanoribbon

Graphene nanoribbon (GNR) is a strip and 1D shape of graphene which can be an appropriate candidate for gas sensing application due to its significant electrical and chemical characteristic. In this study, graphene nanoribbon is employed for the NH3 detection process. The chemical approach is applied for unzipping MWCNTs by using KMnO4, as an oxidative material in graphene oxide nanoribbon synthesis process. The gold comb-like electrodes as a sensor structure is produced by standard deposition and photolithography methods. The quality of the synthesized GNRs is investigated by different analyses such as SEM, XRD, Raman Spectroscopy, and FTIR. In addition to GNR sensor preparation, AuGNR sensor is fabricated by gold sputtering deposition on a GNR sensor surface. The experimental results for sensors indicate that AuGNR and GNR sensors could be the appropriate choices for NH3 detection. The experimental tests for AuGNR and GNR sensors are performed for different NH3 concentration at room temperature which showed 34% and 12.1% response for 25 ppm NH3 respectively. Furthermore, in 25 ppm for the AuGNR sensor, the sensor shows 224 s for response time, and 178 s for recovery time for a graphene-based sensor. All the tests are carried out at room temperature.

High-performance switchable grating based on pre-transitional effect of antiferroelectric liquid crystals.

An optical phase grating prototype based on the homeotropic aligned antiferroelectric liquid crystal (AFLC) is demonstrated. By applying an in-plane electric field using comb-like electrodes, the helical structure of AFLC is deformed with the molecules rotating parallel to the electric field because of dielectric anisotropy. This deformation is called the pre-transitional effect of AFLC and induces biaxiality. By using this effect, a switchable phase grating is constructed using a 40μm thick cell filled with (S)-MHPOBC at 85°C. For 532nm TM polarized incident light, the maximum diffraction efficiency of 37.0% is achieved at the electric field of 1.8V/μm for the ± 1st order diffraction. The rise and decay times for the 1st order diffraction pattern are 510μs and 210μs, respectively. The high diffraction efficiency achieved under low field makes it promising for future electro-optical applications.

67. Cortical evoked potentials after stimulation of cutaneous nerve fibres by micro-patterned electrodes with different interrail gaps

To demonstrate that selective stimulation of intraepidermal nociceptive free endings can be performed using a micro-patterned comblike electrode with interrail gap of 150 μm. In 5 healthy subjects, we stimulated the skin of the hand dorsum with the micro-patterned electrode and with a similar electrode with interrail distance of 1 mm. Stimulation was performed with bursts of 10 pulses, 0.2 ms width each, period of 1 ms either delivered randomly or with constant rate. Cortical responses were recorded from Cz-Au and C3′/C4′-Fz. Stimulating with 1 mm electrode C3′/C4′ recordings showed N20 and W shaped SEP complex; Cz-Au derivation produced a smaller W complex and later smaller N1-P1 waves. Stimulating with 150 μm electrode C3′/C4′ recordings showed only the N1-P1 complex, while no early or medium-latency responses were visible; the Cz-Au recordings showed the N2-P2 complex. The 1 mm gap electrode stimulated large afferents, responsible of the medium-latency components of SEP W. Such components could not be detected with the 150 μm, indicating that large afferents were not stimulated and only small fibre nociceptive afferents were responsible for the late components. The micro-patterned electrode can be considered selective for nociceptive afferents.

Refined model of low-impedance film resistors with a comb-like structure

Using the methods of finite element and conformal mapping, analytical models with low and ultralow resistance of the film resistors of the main types of comb-like (interdigital) structures with an arbitrary ratio between the surface resistivities of resistive and conductive films have been worked out. In the resultant resistance, the resistances of comb-like and connecting electrodes are taken into account, as well as the additional resistance caused by the passage of the current from the conductive to the resistive film and vice versa. The conditions under which an interface between the films can be treated as an equipotential surface are revealed. An equivalent circuit of low-impedance comb resistors, which are used as the sensors of the current in the circuits of stabilization and control, as well as thermal and current protection.

Iterative Precise Conductivity Measurement with IDEs.

The paper presents a new approach in the field of precise electrolytic conductivity measurements with planar thin- and thick-film electrodes. This novel measuring method was developed for measurement with comb-like electrodes called interdigitated electrodes (IDEs). Correction characteristics over a wide range of specific conductivities were determined from an interface impedance characterization of the thick-film IDEs. The local maximum of the capacitive part of the interface impedance is used for corrections to get linear responses. The measuring frequency was determined at a wide range of measured conductivity. An iteration mode of measurements was suggested to precisely measure the conductivity at the right frequency in order to achieve a highly accurate response. The method takes precise conductivity measurements in concentration ranges from 10−6 to 1 M without electrode cell replacement.

Flexible humidity sensor based on Au nanoparticles/graphene oxide/thiolated silica sol–gel film

Novel flexible impedance-type humidity sensors that were based on gold nanoparticles (AuNPs) and graphene oxide (GO) were fabricated by a combination of self-assembly and the sol–gel technique. A hydrolyzed 3-mercaptopropyltrimethoxysilane (MPTMOS) sol–gel solution that contained GO was firstly dropped on to the surface of a pair of comb-like Au electrodes on a polyethylene terephthalate (PET) substrate, and then AuNPs were assembled onto the thiol groups of the sol–gel network. The formed AuNPs were characterized by UV–vis spectroscopy. The microstructure of the AuNPs/GO/MPTMOS sol–gel film was analyzed by atomic force microscope (AFM) and scanning electron microscopy (SEM). The effects of the AuNPs and the amount of GO added on the flexibility, electrical and humidity sensing properties of the AuNPs/GO/MPTMOS sol–gel films on a PET substrate were investigated. The sensor that was made from the AuNPs/GO/MPTMOS sol–gel film with 9.0wt% added GO exhibited the greatest flexibility, sensitivity, linearity and long-term stability. The effects of applied frequency, ambient temperature, response and recovery times on the impedance of the flexible humidity sensor were also investigated. The sensing mechanism of the AuNPs/GO/MPTMOS sol–gel film was explained with reference to impedance plots.

Residual Gas Noise in the Test-mass Module for DECIGO Pathfinder

DECIGO Pathfinder is the first milestone mission for DECIGO, a future gravitational wave antenna. In DPF, residual gas noise acting on the test mass is estimated to increase and exceed the requirement for force noise of 1 × 10-15 N/√Hz due to geometry of the test-mass module. We performed a Monte Carlo simulation to calculate the residual gas noise and found that the engineering model of the test-mass module cannnot satisfy the requirement. To reduce the gas noise, we present revised geometry of the test-mass module using comb-like electrodes.

Effects of ion insertion on cycling performance of miniaturized electrochemical capacitor of carbon nanotubes array

Capacity degradation and ion insertion of a miniaturized electrochemical capacitor are studied using ionic liquid [EMI] [TFSI] as the electrolyte. This capacitor is featured with two comb-like electrodes of vertical carbon nanotubes, ∼70 μm in height and 20 μm in interelectrode gap. We quantify the levels of ion insertion damage with Raman spectroscopy after the electrode experiences 120 consecutive voltammetric cycles to various potential limits. Distinct structural damage emerges due to [EMI] when the negative potential reaches −1.7 V, and those due to [TFSI] arise when the positive potential reaches 1.7 V vs. RHE. Judging from the peak broadenings, [EMI] is more detrimental than [TFSI]. When the voltage window ΔU is set as less than or equal to 2.8 V, both electrode potentials are within the two intercalation limits, little or no decay is observed in 104 charge/discharge cycles. When ΔU is 3.4 V, the positive potential exceeds the upper limit, but the negative potential stays within the lower limit, the cell capacitance decreases moderately. When ΔU increases to 3.8 V, both electrodes suffer from damages because of exceeding the intercalation limits. And the cell capacitance decreases substantially, even leading to a premature failure.

Dual mode acoustic wave sensor for precise pressure reading

In this letter, a Microelectromechanical system acoustic wave sensor, which has a dual mode (lateral field exited Lamb wave mode and surface acoustic wave (SAW) mode) behavior, is presented for precious pressure change read out. Comb-like interdigital structured electrodes on top of piezoelectric material aluminium nitride (AlN) are used to generate the wave modes. The sensor membrane consists of single crystalline silicon formed by backside-etching of the bulk material of a silicon on insulator wafer having variable device thickness layer (5 μm–50 μm). With this principle, a pressure sensor has been fabricated and mounted on a pressure test package with pressure applied to the backside of the membrane within a range of 0 psi to 300 psi. The temperature coefficient of frequency was experimentally measured in the temperature range of −50 °C to 300 °C. This idea demonstrates a piezoelectric based sensor having two modes SAW/Lamb wave for direct physical parameter—pressure readout and temperature cancellation which can operate in harsh environment such as oil and gas exploration, automobile and aeronautic applications using the dual mode behavior of the sensor and differential readout at the same time.