Micro Gas Sensor Array for Monitoring Highly Toxic Gases

Recently,the possibility of a disaster due to the improper use of highly toxic gases which are known as agents throughout the world has been increased.Therefore,the development of technology for countermeasure against CWA has been highly demanded.In this study,thick film SnO_2-based gas sensing devices were prepared and the sensing properties for the four different kinds of simulants such as dimethyl methyl phosphonate (DMMP),acetonitrile,dichloromethane and dipropylene glycol methyl ether have been investigated.And a micro sensor array consists of six devices was prepared using MEMS technology to provide high selective and reliable sensing system for the detection of chemical warfare agents.The micro gas sensor array prepared showed good sensitivity and selectivity to CWA.

SILICON NEEDLE ARRAY ON FLEXIBLE SUBSTRATE FOR FLUID TRANSFER

Transdermal delivery is an attractive alternative, but it is limited by the extremely low permeability of skin. To solve this problem, a novel means--micro needle array based on micro electro-mechanical system （MEMS） technology, is provided to increase permeability of human skin with efficiency, safety and painless delivery. The fabrication method consists of a sequence of deep-reactive ion etching （DRIE）, anisotropic wet etching and conformal thin film deposition. The novel technology can enable the realization of micro fabricated micro needle array on a flexible silicon substrate. The micro needle array can be mounted on non-planar surface or even on flexible objects such as a human fingers and arms. The fabricated hollow wall straight micro needles are 200 μm in length, 30 μm inner diameter, and 50 μm outer diameter with 250 μm center-to-center spacing. Flow rate test proves that the polymeric base construction is important to function of micro needles array in package. Glucose solvent tests show that surface tension is the dominant force to affect the characters of flow in micro needles channel.

Polarization Band Effect and MEMS-Based Plasma Generation

We find that effects resulting from micro/nano scale structures can regulate space charges which excite and lead to the special electric field distribution featuring the flux convergence band structure. It is here referred to as the polarization band effect, which stems from the specific field-induced interactions among atoms and molecules. The micro/nanoelectrode array structures were designed and fabricated using the non-silicon micro/nano processing technology, forming micro/nano electrode arrays-based plasma microelectromechanical systems(NPMEMS). The integrated NPMEMS device can be used to regulate the inner energy states of matters and generate plasma based on the polarization band effect, all within a single chip-size limited local area or extending into a large volume space with the deployment of a distributed array of multiple devices. Its special physical and chemical properties can be utilized to greatly improve the efficiency of potential application systems or solve mechanism-level challenges in plasma-related applications of multiple fields.

Experimental investigations on the heat transfer characteristics of micro heat pipe array applied to flat plate solar collector

This paper introduces a novel fiat plate solar collector （FPC） using micro heat pipe array （MHPA） as a key element. To analyze the thermal transfer behavior of flat plate solar collector with micro heat pipe array （MHPA-FPC）, an indoor experiment for thermal transfer characteristic of MHPA applied to FPC was conducted by using an electrical heating film to simulate the solar radiation. Different cooling water flow rates, cooling water temperatures, slopes, and contact thermal resistances be- tween the condenser of MHPA and the heat exchanger were tested at different heating powers. The experimental results in- dicate that MHPA-FPC exhibits the enhanced heat transfer capability with increased cooling water flow rate and temperature. Total thermal resistance has a maximum decline of approximately 10% when the flow rate increases from 180 to 360 L h-1 and 38% when the cooling water temperature increases from 20~C to 40~C. When the inclination angle of MHPA-FPC ex- ceeds 30~, the slope change has a negligible effect on the heat transfer performance of MHPA-FPC. In addition, contact thermal resistance significantly affects the heat transfer capability of MHPA-FPC. The total thermal resistances lowers to nearly half of the original level when contact material between the condenser of MHPA and the heat exchanger changes from conductive silicone to conductive grease. These results could provide useful information for the optimal design and operation of MHPA-FPC.

Light field head-mounted display with correct focus cue using micro structure array

A new type of light fiehl display is proposed using a head-mounted display （HMD） and a micro structure array （MSA, lens array or pinhole array）. Each rendering point emits abundant rays from different directions into the viewer＇s pupil, and at one time the dense light field is generated inside the exit pupil of the HMD through the eyepiece. Therefore, the proposed method not only solves the problem of accommodation and convergence conflict in a traditional HMD, but also drastically reduces the huge data in real three-dimensional （3D） display. To demonstrate the proposed method, a prototype is developed, which is capable of giving the observer a real perception of depth.

Numerical and Experimental Investigation on the Performance of Battery Thermal Management System Based on Micro Heat Pipe Array

Battery thermal management is very crucial for the safe and long-term operation of electric vehicles or hybrid electric vehicles.In this study,numerical simulation method is adopted to simulate the temperature field of Li-ion battery cell and module.It is proved that the maximum temperature and maximum temperature difference of battery cell and module increase with the increase of charge/discharge rate(C-rate)of the battery.For battery module,it can reach a maximum temperature of 61.1℃at a C-rate of 2 under natural convection condition with the ambient temperature of 20.0℃.A battery thermal management system based on micro heat pipe array(BTMS-MHPA)is deeply investigated.Experiments are conducted to compare the cooling effect on the battery module with different cooling methods,which include natural cooling,only MHPA,MHPA with fan.The maximum temperature of battery module which is cooled by MHPA with a fan is 43.4℃at a C-rate of 2,which is lower than that in the condition of natural cooling.Meanwhile,the maximum temperature difference was also greatly reduced by the application of MHPA cooling.The experimental results confirm that the feasibility and superiority of the BTMS-MHPA for guaranteeing the working temperature range and temperature uniformity of the battery.

Performance simulation and optimization of new radiant floor heating based on micro heat pipe array

This paper proposes two new radiant floor heating structures based on micro heat pipe array(MHPA),namely cement-tile floor and keel-wood floor.The numerical models for these different floor structures are established and verified by experiments.The temperature distribution and heat transfer process of each part are comprehensively obtained,and the structure is optimized.The results show that the cement-tile floor has the better heat transfer performance of the two.When under the same inlet water temperature and flow rate,the keel-wood floor's surface temperature distribution is about 2℃ lower than that of the cement-tile floor.The inlet water temperature of cement-tile floor is about 10℃ lower than that of keel-wood structure when the floor surface temperature is the same.During a longitudinal heat transfer above MHPA,the floor surface temperature decreases by 0.5℃ for every 10 mm filling layer increase.In order to reduce the non-uniformity of the floor's surface temperature and improve the thermal comfort of the heated room,the optimal structure for a floor is given,with the maximum surface temperature difference reduced by 3.35℃.We used research focusing on new radiant floor heating,with advantages including high efficiency heat transfer,low water supply temperature,simple waterway structure,low resistance and leakage risk,to provide theory and data to support the application of an effective radiant floor heating based on MHPA.

Partially-Premixed Combustion Characteristics and Thermal Performance of Micro Jet Array Burners with Different Nozzle Spacings

In order to develop a burner with uniform temperature field,the combustion characteristics and thermal performance of partially premixed methane/air jet flames were experimentally studied by using micro jet array burners.The circular tubes of 1.0-mm inner diameter and 1.5-mm outer diameter were used as nozzles.The effects of nozzle spacing and equivalence ratio on flame phenomenology,temperature distribution and pollutant emissions were respectively investigated by camera photography,thermocouple measurement and sampling analysis.Results show that there are two clean flame patterns:clean merged-flame and clean non-merging flames.The flame patterns depend on the strength of flame interaction,the equivalence ratio of the mixture and the quantity of air entrainment through the gap between nozzles.The burners with small nozzle spacing such as 2 mm and 2.5 mm tend to produce fully merged flame with low equivalence ratio limit and the corresponding temperature fields are very uniform with fluctuations less than 0.3%,but a small increase in equivalence ratio will lead to rapid deterioration of combustion property.The burner with a medium spacing of 3 mm can produce partially merged flame in a wide equivalence ratio range with low emissions,and the temperature fluctuation can be less than 0.5%(<7 K)in the optimal region.The burner with a large spacing of 4 mm will basically form independent array flames with the largest temperature fluctuation over 1%,while it can achieve clean combustion under high equivalence ratio due to large air entrainment.Comprehensive analysis shows that the micro jet array burner with medium nozzle spacing of 3 mm has the best combustion characteristics and thermal performance.

Thermal Performance of a Micro Heat Pipe Array for Battery Thermal Management Under Special Vehicle-Operating Conditions

The thermal management of battery systems is critical for maintaining the energy storage capacity,life span,and thermal safety of batteries used in electric vehicles,because the operating temperature is a key factor affecting battery performance.Excessive temperature rises and large temperature differences accelerate the degradation rate of such batteries.Currently,the increasing demand for fast charging and special on-vehicle scenarios has increased the heat dissipation requirements of battery thermal management systems.To address this demand,this work proposes a novel micro heat pipe array(MHPA)for thermal management under a broadened research scope,including high heat generation rates,large tilt angles,mild vibration,and distributed heat generation conditions.The experimental results indicate that the temperature difference is maintained 3.44°C at a large heat generation of 50 W for a limited range of tilt angles.Furthermore,a mild vehicle vibra-tion condition was found to improve temperature uniformity by 3.3°C at a heat generation of 10 W.However,the use of distributed heat sources results in a temperature variation of 3.88°C,suggesting that the heat generation distribution needs to be considered in thermal analyses.Understanding the effects of these special battery-operating conditions on the MHPA could significantly contribute to the enhancement of heat transfer capability and temperature uniformity improvement of battery thermal management systems based on heat pipe technologies.This would facilitate the realization of meeting the higher requirements of future battery systems.

Influence of Parameters in the Design of a Faceted Structure for Incoherent Beam Shaping

A reflective faceted structure is proposed to reshaping an incoherent light beam into two focalized spots-To obtain the desired irradiance distribution on a detector,custom optimization function is written,and the two dimensional tilt angles of each facet are optimized automatically in a pure non-sequential mode in Zemax OpticStudio 16.The result is also confirmed inside LightTools&2 from Synopsys.For measuring the quality of the optimization result in the case of two spots focalization,four factors including efficiency on the detector,uniformity,the root mean square error and the correlation coefficient are calculated.These four factors are used to evaluate the influence of several parameters on the irradiance distribution.These parameters include the incidence angle,the divergence angle,the facet size,the source type and the resolution of the facet angular positions.Finally,an analysis of those parameters is made and the performance of this type of component is demonstrated.

Highly precise micro torsion angle detection by fringe array

Pringe array is proposed as the cooperated target in the precise torsion angle detection. The target fringe array image is generated according to the structure of the optical system, and the torsion angle detection algorithm is analyzed in response to the gray distribution of the image. The factors affecting the detection precision of the fringe torsion angle are analyzed theoretically and numerically. It indicates that the detection precision of the torsion angle is 1 angular second or even less, carefully selecting the detector array. Significantly, experiments are performed to demonstrate the precision and the results match well with the simulations.