Finger Contact Research Articles

Metal Grid Contact Design for Four-Terminal Tandem Solar Cells

Flat-panel tandem solar cells have demonstrated the potential to exceed the efficiencies of their single-junction constituents. However, robust design rules for tandem solar cells are currently lacking, slowing the development of cost-effective implementations of this technology. A double-junction solar cell with four-terminal (4T) architecture stacks two electrically independent subcells and avoids current-matching losses, resulting in two main advantages over the conventional integrated two-terminal (2T) architecture: a higher energy yield and a loosened constraint on material bandgap combinations. Because both subcells are contacted independently in a 4T tandem, multiple stacked semitransparent contacts are needed, causing optical and series resistance losses. Moreover, for stationary flat-panel tandems, contacts need to be optimized for a varying direction of incident sunlight. In this study, we develop a framework for optimizing metal grid contacts for 4T tandem solar cells and quantify the electrical and optical loss associated with these contacts. We also explore the range of conditions for which it is beneficial to align metal grid contact fingers. We find that, for most applications, the front and back contacts of the top cell should be aligned, resulting in a decrease in energy yield loss between 5% and 15%, while aligning the bottom cell contacts is not beneficial and may even reduce total energy yield. Finally, we show that for nonideally matched subcell pairings, the contacts loss in a 4T tandem is not enough to counter the yield benefit of 4T over 2T tandems, while the contact loss may make the yield for more ideally matched subcells be comparable for 2T and 4T devices.

134 - Early Mortality Due to Cardiovascular Disease for Patients with Myelodysplastic Syndromes (MDS) Living in Areas with Lower Cardiovascular Performance Outcomes

Rotational screen printing (RSP) has recently attracted attention as a highly promising high-throughput alternative for the metallization of Silicon solar cells. Compared to other metallization approaches, RSP is already a well-developed printing method which has been used for various industrial applications during the last decades. The unique benefit of this technology is the ability to apply a thick film metallization combined with a high throughput. Within the present work, we will discuss the actual achievements and challenges of this approach. We show the results of Aluminium back surface solar cells with a RSP rear side metallization and a mean conversion efficiency of η = 19.4 % compared to reference solar cells with flatbed screen printed rear side metallization and a conversion efficiency of η = 19.3 %. We further investigate the properties of fine line cylinder screens used for RSP and conventional flatbed screen printing. Using RSP with a fine line cylinder screen, we printed contact fingers with a mean width down wf = 61 µm. Finally, we discuss the path to a further optimization of this highly promising approach.

High-efficiency c-Si based interdigitated point contact back heterojunction solar cells

We report on the modeling and performance optimization studies of point contact back heterojunction (BHJ) solar cells. BHJ solar cell technology is a combination of front heterojunction (a-Si:H/c-Si) solar cell technology and interdigitated back junction c-Si solar cell technology. In this work, both emitter (p+-a-Si:H) and back surface field (BSF, n+-a-Si:H) were formed at the rear side as an array of interdigitated points, where their respective contacts formed an interdigitated pattern. The gap between p-type and n-type contact fingers was fixed at 10 µm. The n+-a-Si:H (i.e. BSF) circular diameter was fixed while emitter size was varied, and vice versa. Simulation was also performed with and without passivation layer underneath emitter and BSF. We also investigated the impact of surface texture size on cell efficiency. By varying surface texture size, viz. pyramid height and base width, an efficiency as high as 26.61% was obtained with 761 mV Voc, 41 mA/cm2 Jsc, and 84.5% FF for a small pyramid structure with 2 µm height and 4 µm base width.

Optimized Metallization for Interdigitated Back Contact Silicon Heterojunction Solar Cells

We report on the design and manufacturing of interdigitated back contact cells based on the silicon heterojunction technology. The influence of geometry and overlap of the doped amorphous silicon layers forming the contact fingers on device performance have been investigated by simulation. Two contact formation concepts, with and without a TCO interlayer – an indium tin oxide/silver (ITO/Ag) stack, and a direct aluminum (Al) metallization – are experimentally evaluated. The former retains good passivation but leads to a too high contact resistivity, the latter shows the opposite behavior, but yields a slight benefit in terms of overall performance achieving more than 20% of efficiency. We show that in this case a contact system is formed whose properties can be tuned by annealing, enabling a trade‐off between VOC and FF.Structure of the presented solar cell; a SiNX layer covers the front side, the rear side is passivated by overlapping layer stacks of intrinsic and doped amorphous silicon, the latter are contacted by aluminum.

P147 Effects of cTBS on the integration of haptic light fingertip contact and body sway

Question In the present study we aimed to investigate the effects of continuous theta burst stimulation (cTBS) over the posterior parietal cortex (PPC) and how it effects body sway and the integration of light touch. Methods In right-handed young adults, cTBS with an intensity of 80% of the passive motor threshold was applied for 60 s over the left and right Posterior Partial Cortex. Additionally, a sham condition was applied. Target locations were identified using real-time neuronavigation. Participants were tested blindfolded in quiet upright Tandem-Romberg stance before and after each stimulation interval. During these tests they were instructed to actively initiate and cease finger contact with an earth-fixed referent in response to an acoustic signal. Testing was carried out on two non-consecutive sessions. Body sway was recorded in terms of Centre of Pressure (CoP) and trunk kinematics in addition to forces and torques at the contact point. Results The results of 13 healthy right handed participants reveal that cTBS over the right PPC affected postural control. The overall level of body sway was decreased after inhibition, while the effect of Light Touch was still present. Inhibition of the left PPC or sham stimulation did not decrease the overall level of body sway. Conclusion The cause of this effect might be strategies of the motor control system that lead to a co-contraction and thus reducing body sway. However, this does not mean that participants were more stable. Another possible explanation might be that inhibition of the right PPC disrupts processes for state estimation of body sway in spatial reference frames or mechanisms of stability self-exploration (i.e. Zatsiorsky and Duarte, Motor Control, 1999; Ehrenfried et al., Brain Res Cogn Brain Res, 2003; Kiemel et al., J Neurophysiol, 2006).

RETRACTED ARTICLE: Estimation of contact forces of underactuated robotic finger using soft computing methods

Underactuated robotic finger could be used as adaptive mechanism with simple control algorithm. In this study the main aim was to estimate the robotic finger contact forces by soft computing methods. Soft computing approach was applied in order to overcome high nonlinearity in the finger behavior. Kinetostatic analysis was performed in order to extract the input/output data samples for the soft computing methods. The main goal was to estimate the contact forces based on contact locations with the objects. Seven soft computing methods were applied: genetic programming, support vector machine, support vector machine with firefly algorithm, artificial neural network, support vector machine with wavelet transfer function), extreme learning machine and extreme learning machine with wavelet transfer function. The reliability of these computational models was analyzed based on simulation results. Extreme learning machine with wavelet transfer function shown the best accuracy for the contact forces estimation.

The Capturing of Space Debris with a Spaceborne Multi-fingered Gripper

With the massive launching of spacecraft, more and more space debris are making the low Earth orbit (LEO) much more crowded which seriously affects the normal flight of other spacecrafts. Space debris removal has become a very urgent issue concerned by numerous countries. In this paper, using SwissCube as a target, the capturing of space debris with a spaceborne four-fingered gripper was studied in order to obtain the key factors that affect the capturing effect. The contact state between the gripper fingers and SwissCube was described using a defined contact matrix. The law of momentum conservation was used to model the motion variations of the gripper and SwissCube before and after the capturing process. A zero-gravity simulation environment was built using ADAMS software. Two typical kinds of capturing processes were simulated considering different stiffness of fingers and different friction conditions between fingers and SwissCube. Comparisons between results obtained with the law of momentum conservation and those from ADAMS simulation show that the theoretical calculations and simulation results are consistent. In addition, through analyzing the capturing process, a valuable finding was obtained that the contact friction and finger flexibility are two very important factors that affect the capturing result.

Preliminary investigation of arterial aging derived from the iPhone photoplethysmography: focused on finger contact pressure

Preliminary investigation of arterial aging derived from the iPhone photoplethysmography: focused on finger contact pressure

Flexo-printed Busbarless Solar Cells for Multi-wire Interconnection

Flexographic printing is a high-throughput rotational relief printing method and represents a promising innovative approach for the front side metallization of silicon solar cells. The ability to realize narrow contact fingers with very low silver consumption makes this technology particularly interesting for busbarless solar cells with wire-interconnection like Meyer Burger's SmartWire Connection Technology (SWCT). This study intends to provide a comprehensive evaluation of the general feasibility for this approach. Fundamental printing tests are carried out to investigate important influence parameters like the flexible printing plate and the correlation between printing pressure and contact finger width. We found out that contact finger elements on elastomer printing plates down to an actual width of wf = 7 ± 2 μm can be realized using a high-resolution laser-engraving process. Furthermore, we show that printed contact finger width increases by approx. Δwf ≈ 10 μm for each Δploc = 0.05 MPa of pressure increase and thus has a strong impact on the contact grid. Busbarless Al BSF Cz-Si solar cells with flexo-printed front side metallization are fabricated and measured using Pasan GridTOUCH/SpotLIGHT-system. The best group of solar cells obtains a mean conversion efficiency of η = 19.0% and a maximum conversion efficiency of ηmax = 19.4%. A mini-module with the best two solar cells achieved a aperture conversion efficiency of η = 15.8%. Causes for cell-to-module losses are investigated and discussed in detail. In summary, we demonstrate the successful application of flexographic printing technology for the front side metallization of busbarless solar cells with multi-wire interconnection.

High Speed Dispensing with Novel 6” Print Head

In this study, a new dispensing print head is introduced covering an operational width of 16 cm and therefore allowing for solar cell processing at industrial throughput rates. Like in previous ten nozzle versions, the interior paste flow was designed by computational fluid dynamics (CFD) using rheological parameters of applied Ag-pastes (commercially available pastes), including yield stress, shear thinning and wall slip behaviour. The novel print head features a homogeneous distribution of Ag-paste from an inlet supply with a diameter of Din = 2mm to an outlet slot with a width of ws = 160 mm. A first printing test followed by geometrical characterization of the dispensed contacts revealed a distribution of the contact finger width of wf = 35±1 μm across the whole wafer (156x156mm2) which demonstrates highest precision of the approach. The print head is directly integrated in an inline feasible dispensing platform, developed by ASYS GmbH. Respective nozzle plates can be customized to any desired front side grid regarding nozzle diameter, nozzle pitch and the total number of nozzles. In the actual version, the print head uses two strokes to print 100 contact fingers. Each of the 50 nozzles prints two adjacent contact fingers while moving up and down at a speed of up to vy = 700mm/s. In a first solar cell test sequence with the new 6” print head, a maximum cell efficiency of η = 21.2% on industrially preprocessed Cz-PERC samples was reached which demonstrates a successful launching of the print head.

Analyzing of flexible gripper by computational intelligence approach

Adaptive grippers should be able to detect and recognize grasping objects. To be able to do it control algorithm need to be established to control gripper tasks. Compliant underactuated mechanisms with passive behavior can be used for modelling of adaptive robotic fingers. Undearactuation is a feature which allows fully adaptability of robotic fingers for different objects. In this study gripper with two fingers was established. Finite element method (FEM) procedure was used to optimize the gripper structural topology. Kinetostatic model of the underactuated finger mechanism was analyzed. This design of the gripper has embedded sensors as part of its structure. The use of embedded sensors in a robot gripper gives the control system the ability to control input displacement of the gripper and to recognize specific shapes of the grasping objects. Since the conventional control strategy is a very challenging task, soft computing based controllers are considered as potential candidates for such an application. The sensors could be used for grasping shape detection. Given that the contact forces of the finger depend on contact position of the finger and object, it is suitable to make a prediction model for the contact forces in function of contact positions of the finger and grasping objects. The prediction of the contact forces was established by using a soft computing (computational intelligence) approach. To perform the contact forces estimation adaptive neuro-fuzzy (ANFIS) methodology was used. FEM simulations were performed in order to acquire experimental data for ANFIS training. The main goal was to apply ANFIS network in order to find correlation between sensors’ stresses and finger contact forces. Afterwards ANFIS results were compared with benchmark models (extreme learning machine (ELM), extreme learning machine with discrete wavelet algorithm (ELM-WAVELET), support vector machines (SVM), support vector machines with discrete wavelet algorithm (SVM-WAVELET), genetic programming (GP) and artificial neural network (ANN)). The reliability of these computational models was analyzed based on simulation results.

Paper-Based Capacitive Touchpad Using Home Inkjet Printer

In this paper, an inkjet-printed paper-based capacitive touchpad is proposed. This touchpad detects finger contact by sensing the change in effective capacitance caused by the skin electrical impedance. A low-cost flexible disposable touchpad with nine capacitive buttons is fabricated, using paper as a substrate. The use of home inkjet printing technology with silver nanoparticle ink makes the fabrication process simple, fast, cheap, and environmentally friendly. The performance of the proposed touchpad is measured with a microcontroller, and tests are conducted for both the cases of finger and touch pen operation. The measured capacitance of the non-touched state is 228–236 pF, whereas the measured capacitance of the touched state is 340–564 pF. The differences in the capacitance of each state are sufficiently large to indicate that a finger has made contact with the touchpad. The sensitivity of the proposed sensor is evaluated, and the parameters of the proposed sensor are compared with those of other paper-based touch pads.

EP 67. Effects of cTBS over the posterior parietal cortex on body sway and the integration of light tactile fingertip contact

Introduction Light contact with an earth-fixed referent reduces body sway in quite standing. Johannsen et al. (Neuroscience Letters, 2014) investigated the progression of sway before and after the passive onset and removal of right-hand fingertip contact. They found that rTMS over the left inferior parietal gyrus (IPG) reduces overshoot of sway after contact removal, which indicates that left IPG plays a role in sensory reorganisation for sway control with right-handed fingertip contact. Bolton et al. (Neuroreport, 2012) demonstrated that disrupting the right prefrontal cortex altered the processing of right arm sensory information in the context of standing balance with light touch. With respect to the hemispheric processing of tactile information in an egocentric frame of reference, Azanon et al. (Current Biology, 2010) showed that disruption of the right posterior parietal cortex (rPPC) impaired position judgements of tactile stimuli on the left forearm relative to the face. These results might indicate that the right hemisphere is involved in the processing of touch within spatial reference frames for postural control of both hands, while the left hemisphere evaluates contralateral touch only. In the present study we aimed to investigate the effects of continuous theta burst stimulation (cTBS) over the right and left (PPC) on body sway and the integration of light tactile fingertip contact. Methods In 14 right-handed young adults, cTBS of an intensity of 80% of the passive motor threshold was applied for 60 seconds over the left and right PPC. In addition, a sham condition was included either over the left or right PPC. Target locations were identified using real-time neuronavigation software. Participants were tested blindfolded in quiet upright Tandem-Romberg stance before and after each stimulation interval. They were instructed to actively initiate and cease finger contact with an earth-fixed referent in response to an acoustic signal. Testing was carried out on two non-consecutive sessions. Body sway was evaluated in terms of Centre of Pressure (CoP) and trunk kinematics in addition to forces and torques at the contact point. Results Current results reveal that cTBS over the right PPC affected postural control in general. The overall level of body sway was decreased irrespective of the availability of fingertip contact. This general effect was not found for either the left PPC or the sham conditions. Conclusion Generally reduced sway may be a sign of a postural control strategy that involves a greater number of co-contractions, which does not automatically imply an improved postural stability. Another possible explanation is that inhibition of the right PPC limits processes involved in the active exploration of the body’s stability state ( Ehrenfried et al. ).

Experimental determination of the Young's modulus for the fingers with application in prehension systems for small cylindrical objects

A new methodology to determine experimentally the Young's modulus of the human fingers has been developed by the authors. The methodology consist in the experimentally variation of the elastic deformation for the finger in contact with a steel cylinder normal loaded from zero to 10 N. The Hertzian model for elastic deformation specific to a point contact between a cylindrical object and the index finger has been used to curve fitting the experimental curve for elastic deformation of the finger in the vicinity of imposed forces from 0.5N to 10 N. Values between 0.07 MPa and 0.2 MPa for Young's modulus of the finger have been obtained, in agreement with the values determined by the other authors using ball finger contacts or finger plane surface contacts.

Electromagnetic-Thermal-Flow Field Coupling Simulation of 12-kV Medium-Voltage Switchgear

Long-term heating and excessive temperature rise will significantly affect the electrical and insulation performance of electric power equipment, causing the potential security risk. In this paper, the temperature rise situation under normal operation of a 12-kV medium voltage switchgear is studied through modeling and simulation method. First, in the simulation analysis of the whole switchgear, based on the theory of eddy-current field, gas flow field, and temperature field, the temperature rise distribution of the switchgear under the condition of natural convection and forced convection is simulated and analyzed. Then, several improvement methods are taken to reduce the temperature rise that emerges in the switchgear, including using spring contact finger structure to replace flexible connection structure, and also the optimization scheme of vacuum circuit breaker (VCB) pole and current transformer (CT). Then, simulation and research of different improvement schemes are conducted based on the electromagnetic-thermal-flow field coupling method. The simulation results of whole switchgear show that the above coupling method is very useful for the calculation of temperature rise. The simulation results also show that the spring contact structure is beneficial to reduce the temperature rise of vacuum interrupter and mechanical connection part. After the modification of design, the temperature rise conditions of the VCB pole and CT are significantly improved.

Flexographic printing – towards an advanced front side metallization approach with high throughput and low silver consumption

Rotational flexographic printing technology is a highly promising approach to increase the productivity of the cost-intensive solar cell metallization process. The ability to realize narrow contact fingers with very low silver consumption makes this technology particularly attractive for the front side metallization of busbarless solar cells in combination with multi-wire interconnection like Meyer Burger’s SmartWire Connection Technology (SWCT). Within this work, we investigate the feasibility of this approach on solar cells with 156mm edge length. Two types of silver inks are prepared and evaluated with focus on optical and electrical properties of the printed front side grid. Both inks achieve sufficient lateral finger resistances below 20Ω/cm. A low specific contact resistance of ρc,95%=3.0±0.6mΩcm2 is obtained with ink A. Using flexographic printing, Aluminum back surface field Czrochalski-grown Silicon busbarless solar cells with a maximum conversion efficiency of η=19.4% (η∅=19.0%) are fabricated and interconnected to a mini-module. The mini-module obtains an aperture conversion efficiency of η=15.8%. The origin of the cell-to-module (CTM) losses are examined in detail. It is shown that a certain part of the CTM-losses originates from the characteristics of the used GridTOUCH I–V-measurement device. Further sources of possible CTM losses are investigated using electroluminescence measurement (EL) and discussed in detail.

Vibrotactile Sensitivity in Active Touch: Effect of Pressing Force

An experiment was conducted to study the effects of force produced by active touch on vibrotactile perceptual thresholds. The task consisted in pressing the fingertip against a flat rigid surface that provided either sinusoidal or broadband vibration. Three force levels were considered, ranging from light touch to hard press. Finger contact areas were measured during the experiment, showing positive correlation with the respective applied forces. Significant effects on thresholds were found for vibration type and force level. Moreover, possibly due to the concurrent effect of large (unconstrained) finger contact areas, active pressing forces, and long duration stimuli, the measured perceptual thresholds are considerably lower than what previously reported in the literature.

Use of Mobile Devices, Social Media, and Crowdsourcing as Digital Strategies to Improve Emergency Cardiovascular Care: A Scientific Statement From the American Heart Association.

Cardiac arrest, acute myocardial infarction (AMI), and stroke affect millions of people in the United States annually.1 Despite significant advances in medical treatments for these conditions, they remain a major public health problem and a leading cause of morbidity and mortality.1 A critical common element in optimizing care and outcomes for these conditions is the timely recognition of symptoms and initiation of treatment. For example, rapid initiation of cardiopulmonary resuscitation (CPR) is associated with improved survival from cardiac arrest.2 Similarly, early recognition and presentation after onset of symptoms of AMI and ischemic stroke enable implementation of critical therapies such as primary angioplasty and thrombolysis, which are known to improve outcomes.1 Indeed, the “Chain of Survival” for emergency cardiovascular and cerebrovascular care (ECCC) starts with prompt identification of the condition and early activation of the healthcare system to rapidly initiate care.3 Unfortunately, despite national efforts that include public education initiatives and clinical practice guideline recommendations from entities such as the American Heart Association (AHA), major gaps remain in the timely identification of symptoms and initiation of ECCC.4–6 As one example, studies of out-of-hospital cardiac arrest (OHCA) have consistently noted delays in the initiation of bystander CPR.7 For AMI, there have been advances in the provision of timely primary angioplasty for ST-segment elevation myocardial infarction (STEMI), as reflected by significant improvements in door-to-balloon times.8 However, the time from patient symptom onset to seeking care for possible myocardial infarction has not improved significantly.9,10 Similarly, for stroke, there continue to be advances in door-to-needle times, but stroke symptom recognition and seeking of treatment by patients and their families remain a major barrier to timely stroke care.11–16 Public and clinician education efforts alone are not sufficient to reduce gaps …

Nitrogen Gas Plasma Generated by a Static Induction Thyristor as a Pulsed Power Supply Inactivates Adenovirus.

Adenovirus is one of the most important causative agents of iatrogenic infections derived from contaminated medical devices or finger contact. In this study, we investigated whether nitrogen gas plasma, generated by applying a short high-voltage pulse to nitrogen using a static induction thyristor power supply (1.5 kilo pulse per second), exhibited a virucidal effect against adenoviruses. Viral titer was reduced by one log within 0.94 min. Results from detection of viral capsid proteins, hexon and penton, by Western blotting and immunochromatography were unaffected by the plasma treatment. In contrast, analysis using the polymerase chain reaction suggested that plasma treatment damages the viral genomic DNA. Reactive chemical products (hydrogen peroxide, nitrate, and nitrite), ultraviolet light (UV-A) and slight temperature elevations were observed during the operation of the gas plasma device. Viral titer versus intensity of each potential virucidal factor were used to identify the primary mechanism of disinfection of adenovirus. Although exposure to equivalent levels of UV-A or heat treatment did not inactivate adenovirus, treatment with a relatively low concentration of hydrogen peroxide efficiently inactivated the virus. Our results suggest the nitrogen gas plasma generates reactive chemical products that inactivate adenovirus by damaging the viral genomic DNA.

Forecasting of Underactuated Robotic Finger Contact Forces by Support Vector Regression Methodology

Robotic manipulators have very strong nonlinearities. Analytical modeling of the robotic gripper is very challenging task. Therefore in this paper soft computing methods is applied in order to estimate contact forces of the robotic finger. Support vector regression (SVR) with radial and polynomial basis functions and the soft computing methods were used. The primary purpose of this study are in clarification of kinetostatic examining of a new finger mechanism utilizing pseudo-unbending body model. The results show the better prediction accuracy with SVR methodology with radial basis function (RBF).