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The purpose of this project is to assist local fruit farmers to increase output value through innovative development, build a distribution network for agricultural products, and increase farmers' income. In the technology of increasing agricultural output value, NCUT's professional team applies smart agricultural technology to monitor fruit trees to prevent pests and diseases, maintain the healthy growth and yield of fruit trees, and solve the problem of lack of labor in farmland. The NCUT team practices strategic marketing and business models to guide fruit farmers to promote local creation and enhance local cultural characteristics. This project assists in the implementation of new quality-guaranteed and value-added technologies, promotes high-quality agricultural products across the country and improves local tourism marketing, and activates agricultural product promotion activities to achieve mutual support between industry and academia. In addition, in response to the 50th anniversary of the World Earth Day, NCUT held a tree planting to save the earth to implement the concept of sustainable environmental development. President Chen, faculty and students planted 500 Cinnamomum camphor seedlings on the NCUT campus in response to the UN Climate Change Framework Convention.Keyword: Environmental Protection, Local Practice, Intelligent Innovation, Intelligent Agricultural Technology, Sustainable Development

An air curtain machine is used in the entrances and exits of public places where air conditioners are used. The high-speed centrifugal or axial fan blows out the air, creating an airflow barrier to prevent air convection inside and outside, reducing air conditioning losses, and maintaining the indoor air quality by preventing dust, insects, and harmful gases from entering the room. Observation of the airflow behavior was conducted using CFD simulation, to explore whether it has a blocking effect, and the air curtain principle was applied to the air purification equipment. It is mainly composed of several rows of arrayed hole air outlets to form a multi-composite air wall. The airflow on the two sides, or below, can be blocked by the composite air wall and integrated into the main airflow, so that the air walls will not affect each other, and form a barrier effect to prevent infection. This research includes the measurement of impedance characteristics for three layers of filters made of different materials. These filters are used as the input characteristic parameters in the simulation analysis. Four scenarios are discussed, including the consultation room, hospital ward, quarantine station, and conference room. From the simulation results, it is known that when there are many people, the equipment can be set to high speed to increase the volume of air, forming a wind wall to effectively block airflow from the people in the chairs, reducing the risk of infection. Note that the rotation speed should not be too high. The air outlet equipment is susceptible to turbulent flow, which will make the airflow deviate from the expected direction and increase the possibility of mutual infection between adjacent people. Partitions can be used to block airflow to reduce the risk of infection.

Blood pressure assessment plays a vital role in day-to-day clinical diagnosis procedures as well as personal monitoring. Thus, blood pressure monitoring devices must afford convenience and be easy to use with no side effects on the user. This paper presents a compact, economical, power-efficient, and convenient wireless plethysmography sensor for real-time blood pressure biosignal monitoring. The proposed sensor facilitates blood pressure signal shape sensing, signal conditioning, and data conversion as well as its wireless transmission to a monitoring terminal. Received data can, subsequently, be compiled and stored on a computer via a Wi-Fi module. During monitoring, users can observe blood pressure signals being processed and displayed on the graphical user interface (GUI)—developed using a virtual instrumentation (VI) application. The proposed device comprises a finger clip optical pulse sensor, analogue signal preprocessing, microcontroller, and Wi-Fi module. It consumes approximately 500 mW power when operating in the active mode and synthesized using commercial off-the-shelf (COTS) components. Experimental results reveal that the proposed device is reliable and facilitates efficient blood pressure monitoring. The proposed wireless photoplethysmographic (PPG) sensor is a preliminary (or first) version of the intended device manifestation. It provides raw blood pressure data for further classification. Additionally, the collected data concerning the blood pressure wave shape can be easily analysed for use in other biosignal observations, interpretations, and investigations. The design approach also allows the device to be built into a wearable system for further research purposes.

Axial flow fans are commonly used for a system or machinery cooling process. It also used for ventilating warehouses, factories, and garages. In the fan manufacturing industry, the demand for varying fan operating points makes design parameters complicated because many design parameters affect the fan performance. This study combines the deep neural network (DNN) with a genetic algorithm (GA) for axial flow design and development. The characteristic fan curve (P-Q Curve) can be generated when the relevant fan parameters are imported into this system. The system parameters can be adjusted to achieve the required characteristic curve. After the wind tunnel test is performed for verification, the data are integrated and corrected to reduce manufacturing costs and design time. This study discusses a small axial flow fan NACA and analyzes fan features, such as the blade root chord length, blade tip chord length, pitch angle, twist angle, fan diameter, and blade number. Afterwards, the wind tunnel performance test was performed and the fan performance curve obtained. The feature and performance test data were discussed using deep learning. The Python programming language was used for programming and the data were trained repeatedly. The greater the number of parameter data, the more accurate the prediction. Whether the performance condition is met could be learnt from the training result. All parameters were calculated using a genetic algorithm. The optimized fan features and performance were screened out to implement the intelligent fan design. This method can solve many fan suppliers’ fan design problems.

In this study, the thermal deformation of a machine tool structure due to the heat generated during operation was analyzed, and embedded cooling channels were applied to exchange the heat generated during the operation to achieve thermal error suppression. Then, the finite volume method was used to simulate the effect of cooling oil temperature on thermal deformation, and the effect of thermal suppression was experimentally studied using a feed system combined with a cooler to improve the positioning accuracy of the machine tool. In this study, the supply oil temperature in the structural cooling channels was found to significantly affect the position accuracy of the moving table and moving carrier. If the supply oil temperature in the cooling channels is consistent with the operational ambient temperature, the position accuracy of the moving table in the Y direction and the moving carrier in the X and Z directions has the best performance under different feed rates. From the thermal suppression experiments of the embedded cooling channels, the positioning accuracy of the feed system can be improved by approximately 25.5 % during the dynamic feeding process. Furthermore, when the hydrostatic guideway is cooled and dynamic feeding is conducted, positioning accuracy can be improved by up to 47.8 %. The machining accuracy can be improved by approximately 60 % on average by using the embedded cooling channels in this study. Therefore, thermal suppression by the cooling channels in this study can not only effectively improve the positioning accuracy but also enhance machining accuracy, proving that the method is effective for enhancing machine tool accuracy.

This study proposes an improved design for a typical sludge continuous feeding drying system connected with three air-source heat pumps. The system’s performance was further improved using air-deflectors on the drying chamber’s internal sidewalls, enhancing the heat and mass transfer between the conveyor sludge and circulating airflow. In this study, numerical analysis was performed to elucidate the deflector designs on the airflow field and thermal temperature field distributions in the drying chamber. The specific moisture extraction rate (SMER) value was quantified to evaluate the system’s overall improvement during experiments. With a suitable deflector design, the average percent water content in sludge could be further reduced to 22.2% with drying time of 18.3 h, and the SMER value could be enhanced from 1.38 kg/kWh to as high as 1.83 kg/kWh with an increment of 32.44%. Moreover, to prevent overloading and frequent shutdown of the compressors, an auxiliary cooling subsystem was designed to attain stable operational conditions. By the auxiliary cooling subsystem design, the compressors’ shutdown can be avoided, the temperature difference between airflow inlets and outlet of the drying chamber can be increased, and SMER value can be further increased to a value of 1.94 kg/kWh.

This study investigated a composite polymer desiccant material&rsquo, s performance, which is prepared by impregnating solid desiccant such as sodium polyacrylate (SAP) on to hygroscopic salts such as lithium chloride (LiCl). Dehumidification performance of the proposed composite polymer desiccant (SAP-LiCl) was analyzed by coating the suitable weight percentage (wt %) of the desiccant onto a single fin-tube heat exchanger (FTHE) system and testing the desiccant-coated heat exchanger (DCHE) in a testing tunnel under various operating conditions. Net dehumidification efficacy of DCHE in terms of sorption and desorption amount and thermal performance (COPth) were analyzed. For instance, with processed air inflow temperature, relative humidity and regeneration temperature setting of 30 &deg, C, 80% RH and 70 &deg, C, DCHE&rsquo, s sorption, desorption amount and COPth were recorded as high as 945.1 g, 1115.1 g, and 0.39, respectively. It was further realized that the performance of the DCHE could be enhanced by modulating the cyclic switching time for dehumidification and regeneration processes. For instance, with the aforementioned processed airflow conditions, when the cyclic switching time tuned as 60 min instead of 10 min for a total time period of 120 min, there is a net 58% improvement to the COPth of the system. It was further observed that, under the same time period corresponding to the increase in cyclic switching time, the overall COPth can be enhanced, however, the water vapor sorption and desorption amounts of desiccant were decreased.

In this study, a multifunctional air and water source heat pump system was developed with a parallel refrigerant piping arrangement, which possessed six operational functions: space cooling (SC), space heating (SH), water heating (WH), water cooling (WC) and two composite operational modes. The two composite operational modes were the SC/WH mode and the SH/WH mode. The performance of the multifuctional heat pump system under different ambient conditions was investigated based on the testing standards of CNS 14464 and CNS 15466. In this study, the effect of the direct water heating (DWH) and circulating water heating (CWH) methods on the performance was investigated. It was found that the water heating performance of the system by the DWH method is better than that of the system by the CWH method. The water heating capacity and COPw,h of the DWH method can be improvement by 2.6% to 22.1% and 2.9% to 50.8%, respectively. Moreover, this study developed a refrigerant pressure balance method to achieve an effective steady state of the refrigerant pressure after operational mode switching. By the refrigerant pressure balance method, the required time to attain the steady state could be greatly reduced&mdash, by 50%. However, the deviation of the refrigerant mass flow rate between the refrigerant pressure balance method and the refrigerant pump down method after operational mode switching ranged from 0.15% to 7.6%.

Accurate temperature control that addresses heat generation is crucial given the development of high-accuracy high-speed machining process. Heat generation leads to a thermal error of machine tools. Therefore, developing high-accuracy machining without appropriate temperature control scheme is challenging. Machine tool coolers for forced convection cooling can effectively control heat generation. However, temperature control accuracy cannot be achieved because the temperature control scheme for machine tool oil cooler encounters nonlinear and time-varying problems with time delay characteristic. This study presents a novel temperature control scheme, namely, Proportional–integral–derivative (PID) control logic based on Smith predictive method. MATLAB simulation software was utilized to determine the specifications of outlet temperature control using hot-gas bypass scheme of high-precision oil cooler with refrigerant R-32. Simulation results revealed that the proposed control scheme present better temperature control accuracy than the traditional PID control. The proposed control scheme can also effectively solve the abovementioned problems through on-site experimental results. The steadystate error of the oil outlet temperature of the high-precision-type machine tool oil cooler can be controlled within 0.1 °C by using the proposed control hot-gas bypass scheme.

This article develops a direct methanol fuel cell (DMFC) with a magnet-actuated bubble removal mechanism. A micro-DC motor is used to control the bubble removal mechanism. The lower magnetic device...

This study investigated the flow bifurcations of flows driven by a pressure gradient in a rectangular curved tube. When fluid flows within a curved tube, due to the centrifugal effect, secondary vortices can be induced in the cross section of the tube. The secondary flow states are dependent on the magnitude of the pressure gradient (q) and the aspect ratio (γ). In this study, the continuation method was applied to investigate the flow bifurcations in a curved tube with increasing pressure gradient (1 < q < 6000) and aspect ratio (0.9 < γ < 1.4).The bifurcation diagrams are composed of solution branches, which are linked by limiting points or bifurcation points. The flow states in a solution branch belong to the same group. The ranges of the flow states and the relationship between the states can also be derived from the bifurcation diagrams. In this study, two types of bifurcation were found, one in the range of 0.9 < γ < 1.17, and another in the range of 1.18 < γ < 1.4. The ranges of stable flow solutions and the distributions of limit and bifurcation points in both pressure gradient and aspect ratio are derived in this study.

A uniform magnetic field distribution is a critical aspect in the transmitter array coil design process for achieving a homogenous vertical magnetic field distribution. The free position and orientation features can thus be implemented in the wireless power charging system. This paper presents vertical magnetic field distribution generated by a single-layer circular flat spiral air core transmitter array coil model analysis and evaluation using a numerical analysis method. This method is developed based on the off-symmetry axis magnetic field distribution due to a circular current loop derived from the Biot-Savart law. The proposed evaluation criteria are used to obtain the vertical magnetic field distribution characteristic of the evaluated array coil model. The vertical magnetic field distribution of several circular flat spiral air core coils, in both single and array coil models with different coil geometries were investigated to obtain the relation between the coil parameters and the distance between the adjoining coil centers to generate uniform vertical magnetic field distribution. A case study was also conducted to analyze and evaluate several array coil model patterns (1 &times, 2 array coil, 1 &times, 3 array coil, 2 &times, 2 array coil, 2 &times, 3 array coil) to meet uniform vertical magnetic field distribution. The array coil model is composed of an identical single circular flat spiral air-core coil. Every single coil has inner coil diameter (Di), outer coil diameter (Do), wire diameter (W), pitch (P) and a number of turns (N) at 25 mm, 47.8 mm, 0.643 mm, 0.03 mm, 17 respectively. The study and evaluation of several array coil pattern models show that the distance between the adjoining coil centers should be defined close to the half of coil outer diameter (1/2Do) to generate close to uniform vertical magnetic field distribution. The vertical magnetic field distribution average and magnetic field effective transmitting areas array coil model with the given coil parameters changing as the effect in variation in distances between the adjoining coil centers.

This study investigated the dehumidification effect of silica gel and sodium polyacrylate desiccants coated on fin and tube heat exchangers under various humidity and temperature conditions. In the system, the two desiccant-coated heat exchangers are periodically operated in mass equilibrium states between dehumidification and regeneration processes. The corresponding cyclic switching times between the two processes are investigated to determine suitable switching times that will further improve the operational efficiency of the system. The experimental results show that while water at a temperature of 50°C was supplied during the regeneration process, the sorption ability was greater and the vapor was discharged in a shorter period of the regeneration process for the sodium polyacrylate desiccant than for silica gel. Thus, the moisture sorption ability of sodium polyacrylate in the system is superior to that of silica gel under the same operational conditions. Suitable cyclic switching times for both des...

The quality characteristics with unilateral specifications include the smaller-the-better (STB) and larger-the-better (LTB) quality characteristics. Roundness, verticality, and concentricity are categorized into the STB quality characteristics, while the wire pull and the ball shear of gold wire bonding are categorized into the LTB quality characteristics. In terms of the tolerance, zero and infinity (∞) can be viewed as the target values in line with the STB and LTB quality characteristics, respectively. However, cost and timeliness considerations, or the restrictions of practical technical capabilities in the industry, mean that the process mean is generally far more than 1.5 standard deviations away from the target value. Researchers have accordingly proposed a process quality index conforming to the STB quality characteristics. In this study, we come up with a process quality index conforming to the LTB quality characteristics. We refer to these two types of indices as the unilateral specification process quality indices. These indices and the process yield have a one-to-one mathematical relationship. Besides, the process quality levels can be completely reflected as well. These indices possess unknown parameters. Therefore, sample data are required for calculation. Nevertheless, interval estimates can lower the misjudgment risk resulting from sampling errors more than point estimates can. In addition, considering cost and timeliness in the industry, samples are generally small, which lowers estimation accuracy. In an attempt to increase the accuracy of estimation as well as overcome the uncertainty of measured data, we first derive the confidence interval for unilateral specification process quality indices, and then propose a fuzzy membership function on the basis of the confidence interval to establish the two-tailed fuzzy testing rules for a single indicator. Lastly, we determine whether the process quality has improved.

Whether it is important components of a machine tool itself or various important components processed by the machine tool, many vital quality characteristics mostly belong to the smaller-the-better type. When the process quality levels of these quality characteristics do not attain to the criteria, friction loss may increase during the machine operation, affecting not only the process precision and accuracy but also the lifetime of the product. Therefore, this study applied a smaller-the-better six-sigma quality index simultaneously demonstrating process quality level and process yield. Besides, in coping with statistical process control data, a one-tail confidence-interval-based fuzzy testing method was developed to evaluate process quality. Because this approach is built on the basis of confidence intervals, it can reduce the possibility of misjudgment resulting from sampling errors as well as integrate past experience to enhance the accuracy and precision of the assessment, and then it can grasp the timeliness of improvement.

In this study, silica gel and sodium polyacrylate desiccants are coated onto a finned tube heat exchanger (Desiccant Coating Heat Exchanger, DCHE), which can absorb the vapor in the process air for dehumidification. In the experiments, the desiccant is coated on fins using the dense coating method, which causes the fixed fin area to be coated with greater amounts of desiccants for a better dehumidification performance. This study discusses the dehumidification performances of a single stage DCHE and two-stage DCHEs in series under different relative humidity conditions of the inlet process air and different regeneration water temperatures. The results show that the thermal coefficient of performance (COPth) of the DCHEs for the two desiccants prepared by the dense coating method is better than that of DCHEs with the general immersing coating method by a factor of 2&ndash, 2.4. The two-stage DCHEs in series have a lower supply humidity ratio than a single stage DCHE at different inlet humidity levels, and they can be used in the industry when a special low humidity manufacturing process is required. The overall dehumidifying capacities of two-stage series-connected DCHEs at regeneration temperatures of 50 &deg, C and 70 &deg, C are approximately twice as high as those of a single stage DCHE. The COPth value of a single stage or two stages increases with an increase in the inlet humidity of the process air. The COPth values of the sodium polyacrylate single stage and two-stage DCHEs are 1&ndash, 1.3 times greater than those of the silica gel single stage and two-stage DCHEs at a high inlet air humidity. Finally, the effects of different regeneration water temperatures on the performance of DCHEs are investigated. With an increase in the regeneration water temperature, the COPth value, dehumidifying capacity and regeneration capacity of single stage or two-stage DCHEs increase as well.

This study presents a multiphysics simulation analysis that was performed for the cooling channel of a built-in spindle. The design of experiments (DOE) method was employed to optimize the dimension of the cooling channel, and a practical machining experiment was performed to validate the effect of the design. In terms of the temperature, pressure drop, thermal deformation, manufacturing cost, and initial cost considerations, the paralleling type cooling channel of the front bearing and the helical type cooling channel of the motor were adopted in the study. After the optimal design of the cooling channel was applied, the bearing temperature was reduced by a maximum decrease of 6.7 &deg, C, the spindle deformation decreased from 53.8 &mu, m to 30.9 &mu, m, and the required operational time for attaining the steady state of the machine tool was shortened from 185.3 min to 132.6 min. For the machining validation, the spindle with the optimal cooling channel design was employed for vehicle part machining, the flatness of the finished workpiece was increased by 61.3%, and the surface roughness (Ra) was increased by 52%. According to the findings for the optimal cooling channel, when the spindle cooling efficiency is increased by the optimal cooling channel design, the thermal deformation and warm-up period can be reduced effectively, and the machining precision can be enhanced. This method is an efficient way to increase the accuracy of a machine tool.

The generating heat from bearings and a motor of a built-in high rotating speed spindle of a machine tool has to be dissipated to attain high machining accuracy. In this study, a machine tool with a coolant cooling system for a high rotating speed spindle was investigated. The cooling channel designs in terms of channel pattern and dimensions by the design of experiment method (DOE) on the cooling effect of the spindle were studied. By the optimized cooling channel design, the cooling efficiency can be improved by 57.6% and the generating temperature in the spindle can be reduced by 25.9°C.

This study proposed an improved design for the typical sludge drying system cooperating with three air-source heat pumps. Performance improvement of the system was conducted by consideration of the internal configuration of the drying chamber and the heat and mass transfer effect of the air in the cabin. Since the heat pump drying system in this study adopts the design of continuous sludge feed, the efficiency of heat and mass transfer between the sludge on the conveyor belt and thet air streams from the condenser in the drying chamber becomes very important. Simulation analysis of the computational fluid dynamics (CFD) software was used to understand the flow field and temperature field distributions in the drying chamber with air deflectors in order to find the appropriate internal configuration design in the drying chamber and system operating parameters. The SMER value (ratio of dehumidification amount and energy consumption) were measured to verify the system improvement effect. The purposed system can enhance the dehumidification SMER value by 32.44%. The simulation temperature differences and the actual measured results are less than 10%, the water content percentage of the discharged dry sludge decrease by 30% after redesign the cabin.

Since the portability feature has been introduced in headphone development, this device now uses a battery as the main built-in power. However, the battery has limited power capacity and a short lifetime. Battery substitution and a conventional battery charger method is an ineffective, inflexible inconvenience for enhancing the user experience. This paper presents an innovative portable audio device battery built-in charger method based on wireless power technology. The developed charging device is composed of a headphone hanger pad for the wireless headphone and a charging pad for the portable wireless audio device battery charging. Circular flat spiral air-core coil was designed and evaluated using a numerical method to obtain optimal vertical magnetic field distribution based on the proposed evaluation criteria. A coil has inner coil diameter of 25 mm, outer coil diameter of 47.8 mm, wire diameter of 0.643 mm, the pitch of 0.03 mm and a number of turns of 17 was chosen to be implemented on the transmitter coil. A magnetic induction technique was adopted in the proposed wireless power transmission module which was implemented using commercial off-the-shelf components. For experimental and validation purposes, a developed receiver module applied to the commercial wireless headphone and portable audio speaker have a built-in battery capacity at 3.7 V 300 mAh. The experimental results show that the wireless power hanger pad prototype can transfer a 5 V induction voltage at a maximum current of 1000 mA, and the power transfer efficiency is around 70%. It works at 110 kHz of operation frequency with a maximum transmission distance of about 10 mm and takes 1 h to charge fully one 3.7 V 300 mAh polymer lithium battery.

Thermal error is the most important source of error in the machine tool, and the thermal deformation caused by the temperature rise during the cutting process often leads to lower machining accuracy and poor quality. About 40%–70% machining error of machine tool is caused by thermal deformation. Considering that it is difficult to avoid the generation of heat during the operation or the cutting process of the machine tool, how to predict the temperature change of the machine tool and then design effective thermal management measures becomes an important task in the development of ultra-high precision machine tools. In this study, the thermal deformation of the machine tool structure due to the heat generated during operation is analyzed, and the embedded cooling channels is applied to exchange the heat generated during the operation to achieve the purpose of thermal error suppression. Then, the finite volume method is used to simulate the effect of cooling oil temperature on the thermal deformation and the thermal suppression is conducted on the feed system in combination of the cooler in order to improve the positioning accuracy of the machine tool. From the simulation results, it is observed that when the temperature of cooling oil is lower in the embedded cooling channels, more heat generated is taken away by the hydrostatic guideway and the average temperature of the hydrostatic guideway is reduced, thus decreasing the thermal deformation. Through the thermal suppression experiment of the embedded cooling channels, the positioning accuracy of the feed system can be improved by about 39.1% during the dynamic feeding process.

Study of negative differential switching behavior is reported in metal-insulator-p-n thyristor structure with a GaAs native thin oxide, where the thin insulator is grown at low temperature by a chemical liquid phase oxide (CLPO) with a thickness at 10nm range. A significant S-shaped negative differential resistance (NDR) is shown to occur that originates from the regenerative feedback in a tunnel metal/insulator/semiconductor (MIS) interface and p-n junction. The influence of oxide thickness on the switching characteristics is investigated. The switching voltages are found to be increased when increasing the oxide thickness, while the holding voltages are almost kept constant even the thyristor exposes under the light.

This study investigated the ambient environmental temperature effect on the positioning accuracy of a periodically-moving carrier. The moving carrier was operated in an environmental chamber in which the operational temperature could be controlled by an air conditioning system. Different operational temperature modes, including a stable environment, a rise in temperature, a decline in temperature, summer daytime hours, and winter nighttime hours in terms of seasonal climate change in Taiwan, were generated within the environmental chamber by an air conditioning system to investigate the operational temperature’s effect on positioning accuracy. From the experimental measurements of a periodically-moving carrier, it is found that the operational temperature conditions can significantly affect the positioning accuracy of the moving carrier, especially in the case of an operational temperature decline. Under stable operational conditions, the positioning accuracy of the moving carrier can be considerably improved. In comparison to the case of an operational temperature decline, the positioning accuracy improvement can reach 29.6%. Moreover, the effect of the temperature distributions within the chamber on the positioning accuracy was further investigated. It was found that, with a parallel flow pattern in the chamber, the positioning accuracy can be further enhanced.

A continuation method, accompanied with a linear stability analysis, is employed to investigate the bifurcation diagram of the flow solutions, as well as the multiple flow states in a cavity with different aspect ratios for parallel motion of two facing lids. The Reynolds number proportional to the wall velocity is used as the continuation parameter, and the evolution of the bifurcation diagrams in cases with different aspect ratios is illustrated. The induced flow patterns are highly dependent upon both the aspect ratios and the moving velocity of the walls. Three different types of bifurcation diagrams and their corresponding flow states are classified according to the aspect ratios. One stable symmetric flow state and one stable asymmetric flow state are identified. The stable asymmetric flow state is obtained at a high aspect ratio and a low Reynolds number. Meanwhile, the regions of stable and unstable flows are distinguished according to the different aspect ratios.

A traditional III-V GaAs/AlGaAs based semiconductor solar cell heterojunction structure, i.e. n-GaAs/n-AlGaAs/n-GaAs/i-GaAs/p-GaAs is used in this study to investigate the surface polymer passivation on this kind of solar cell. For GaAs/AlGaAs solar cell, the top n-GaAs/n-AlGaAs structure is responsible for the selective etching stop layer. The selective etched surface barriers associated with polymer gratings with different aspect ratios, i.e. grating period (gp) to depth (d), are produced on solar cell surface by using the photolithography and Micro Electro Mechanical Systems (MEMS) techniques. A reflective-type diffraction optical grating is fabricated on the surface of the solar cell to redirect the incident light reflected from the solar cell back onto the solar cell surface. The experimental results show that the addition of the surface optical gratings reduce the light reflectivity value as high as 25%. From inspection of surface reflectivity , the average reflectivity is found to be decreased from 12.1% down to 7.9 %.

Effects of a metal oxide structure on the oxygen sensing properties are investigated. In the existence of the etched V-groove gallium oxide geometry, its electrical and sensing properties, i.e., high sensitivity and response time areinvestigated. Grain sizes of the material are dependent on different sputtering conditions and investigated by AFM. Under the partial-voltage circuit measurement, it can be confirmed that the increase of temperature will result in the increase of resistance for the Ga2O3 oxygen sensor. From experiment, good stability and repeatability of the oxide sensor are demonstrated when tested under oxygen concentration. These properties show that the oxide structure has a good potential for high sensitivity oxygen sensor.