Total Contact Area Research Articles

The First Shot is Your Best Shot! Detrimental Biomechanical Effects of Revising Suboptimally Placed Pedicle Screws

everal factors affect the ultimate pullout strength of a pedicle screw. Features inherent to the screw design (its S format—conical or cylindrical, its thread width and pitch length, as well as its outer and inner diameter, just to mention a few) have a strong influence upon the distribution of forces on the metal/bone interface and, therefore, upon the overall pullout strength of the screw (Figure 1). As a general rule, a larger outer diameter (the most important factor), a smaller inner diameter, and a shorter pitch interval, by increasing the total contact area between the bone and the screw, improve its overall pullout strength (4). However, it has already been demonstrated that in osteoporotic patients a screw with larger diameter may not necessarily increase its ultimate pullout strength, and may even result in increased rates of pedicle fractures, as the outer cortex of osteoporotic pedicles has been shown to be significantly thinner than those of normal vertebrae (8).

The Effect of Wallet Thickness on Spine Posture, Seat Interface Pressure, and Perceived Discomfort During Sitting

OCCUPATIONAL APPLICATIONS Occupational sitting has been associated with an increased risk for developing low back pain. The present investigation examined the effects of asymmetrical sitting surfaces induced by a wallet on acute changes in spine/pelvis posture, interface pressure, and discomfort. Compared to level sitting, sitting on a wallet resulted in greater sagittal and lateral spine flexion, a smaller total contact area with the seat pan, and greater gluteal discomfort. At wallet thicknesses of 22 mm and thicker, seat pan contact pressure area decreased and thoracic spine and pelvic angles deviated laterally compared to the no-wallet condition. At a 32-mm wallet thickness, gluteal discomfort increased. These results indicate that sitting for brief periods (15 minutes) on an uneven seating surface greater than 32 mm in thickness causes postural deviations from neutral spine positions and increases gluteal discomfort. This study supports the removal of rear pocket items, especially larger ones, during sitting.TECHNICAL ABSTRACT Background: Occupations in mobile or office settings can involve prolonged seated exposures, increasing the likelihood of low back pain development. The seat-occupant interface can be impeded by wallets or other objects (cell phones, paper documents, etc.) placed in the rear pocket, potentially increasing the risk of developing low back pain directly (nerve compression) or indirectly (altered kinematics). However, there are no published studies that have examined the effect of an uneven seating surface. Purpose: This study aimed to quantify the outcomes of a non-level sitting surface on trunk kinematics, seat pan pressure distribution, and discomfort. Gender differences in responses were also examined. Methods: Twelve males and 12 females sat for 15 minutes each on 4 wallet thicknesses (0, 12, 22, and 32 mm). Sagittal and frontal plane angles of the thoracic, lumbar spine and the pelvis were measured. Seat pressure distribution (total pressure area) and discomfort using a 100-mm visual analogue scale were also collected for each thickness. Results: In the 22- and 32-mm conditions, there was greater pelvic posterior rotation, pelvic left lateral bending, thoracic flexion, and thoracic right lateral bending compared to the 0-mm condition. Males and females showed differences in the magnitude of lateral bend angles at all spine levels; however, both genders demonstrated the same directions of postural compensation. Total pressure area decreased and gluteal discomfort increased with thicker wallets, reaching significance in the 22- and 32-mm conditions, respectively. Conclusions: Sitting on wallets greater than 32 mm in thickness increased gluteal discomfort reporting after short duration exposures. Asymmetrical sitting promotes non-neutral spine postures and reduces seat pan contact area. Asymmetrical sitting is therefore not recommended, even for short duration exposures.

The effect of distal humeral hemiarthroplasty on articular contact of the elbow

BackgroundHemiarthroplasty is a treatment option for selected distal humerus fractures. The purpose of this study was to determine the effect of distal humeral hemiarthroplasty and implant size on elbow articular contact. We hypothesized that implants of varying sizes produce different contact patterns compared with the native elbow. MethodsEight cadaveric arms were tested in an elbow simulator and the kinematics recorded. Three-dimensional reconstructions of bones and cartilage were generated from computed-tomography images to determine contact patterns. The native articulation was compared to optimal, oversized, and undersized implants (Latitude Anatomic Hemiarthroplasty). Changes in contact patterns relative to the native articulation were measured using total contact area and contact patch agreement scores, defined as the sum of distance between contact patches×area, indicating how well contact patches agree with the native contact pattern. FindingsThe native articulation had significantly lower ulnohumeral contact patch agreement scores compared to all tested implants (P<0.05). Mean ulnohumeral and radiocapitellar contact area decreased an average 44% (P=0.03) and 4% (P=0.07) following placement of an optimally sized implant. There was no effect of implant size on contact area or contact patch agreement score (P>0.05). InterpretationShape differences of elbow implants relative to the native joint may be responsible for altered contact patterns and could be improved with design modifications. These changes may predispose the elbow to arthritis. The lack of influence of implant size suggests that implant shape and materials may be more important than implant sizing during surgery.

Plantar Loading During Cutting While Wearing a Rigid Carbon Fiber Insert.

Context : Stress fractures are one of the most common injuries in sports, accounting for approximately 10% of all overuse injuries. Treatment of fifth metatarsal stress fractures involves both surgical and nonsurgical interventions. Fifth metatarsal stress fractures are difficult to treat because of the risks of delayed union, nonunion, and recurrent injuries. Most of these injuries occur during agility tasks, such as those performed in soccer, basketball, and lacrosse. Objective : To examine the effect of a rigid carbon graphite footplate on plantar loading during 2 agility tasks. Design : Crossover study. Setting : Laboratory. Patients or Other Participants : A total of 19 recreational male athletes with no history of lower extremity injury in the past 6 months and no previous metatarsal stress fractures were tested. Main Outcome Measure(s) : Seven 45° side-cut and crossover-cut tasks were completed in a shoe with or without a full-length rigid carbon plate. Testing order between the shoe conditions and the 2 cutting tasks was randomized. Plantar-loading data were recorded using instrumented insoles. Peak pressure, maximum force, force-time integral, and contact area beneath the total foot, the medial and lateral midfoot, and the medial, middle, and lateral forefoot were analyzed. A series of paired t tests was used to examine differences between the footwear conditions (carbon graphite footplate, shod) for both cutting tasks independently (α = .05). Results : During the side-cut task, the footplate increased total foot and lateral midfoot peak pressures while decreasing contact area and lateral midfoot force-time integral. During the crossover-cut task, the footplate increased total foot and lateral midfoot peak pressure and lateral forefoot force-time integral while decreasing total and lateral forefoot contact area. Conclusions : Although a rigid carbon graphite footplate altered some aspects of the plantar- pressure profile during cutting in uninjured participants, it was ineffective in reducing plantar loading beneath the fifth metatarsal.

Comparison of plantar pressures and contact area between normal and cavus foot

BackgroundIn pes cavus, the medial longitudinal arch elevation reduces the contact surface area and consequently increases the corresponding plantar pressure measurements. This poor distribution of loads may produce associated pathology and pain in this or other areas of the body. Normal reference values need to be established in order to determine which patterns are prone to pathology. ObjectivesTo compare the plantar pressures and weight-bearing surface in a population with pes cavus to a population with neutral feet. MethodThe sample comprised 68 adults, 34 with pes cavus and 34 with neutral feet. The Footscan USB Gait Clinical System® was used as a platform to measure the total contact area and plantar pressure under the forefoot, midfoot, hindfoot, each metatarsal head, and the overall metatarsal area. A statistical analysis of the data was performed using Student's t-test for independent samples. ResultsThe pes cavus subjects showed a significant reduction in their weight-bearing area [neutral feet: 165.04 (±20.68)cm2; pes cavus: 118.26 (±30.31)cm2; p<0.001] and significantly increased pressures under all zones of the forefoot except the fifth metatarsal [metatarsal pressure: in neutral feet 503,797 (±9.32)kPa; in pes cavus 656.12 (±22.39)kPa; p<0.001]. ConclusionsCompared to neutral feet, pes cavus feet show a reduction in total contact surface and the load under the first toe. A significant increase is present in the load under the metatarsal areas, but the relative distribution of this load is similar in both groups.

Three dimensional, radiosteriometric analysis (RSA) of equine stifle kinematics and articular surface contact: A cadaveric study

Studies examining the effect of stifle joint angle on tibial rotation, adduction-abduction angle and articular contact area are lacking. To test the hypothesis that tibial rotation, adduction-abduction angle and articular contact area change with stifle joint angle. Descriptive study of normal kinematics and articular contact patterns of the equine stifle through the functional range of motion using 3 dimensional (3D) radiosteriometric analysis (RSA) and equine cadaver stifles. Multiple, radiopaque markers were embedded in the distal femur and proximal tibia and sequential, biplanar x-rays captured as the stifle was passively extended from 110° to full extension. Computer-programmed RSA was used to determine changes in abduction-adduction and internal-external rotation angles of the tibia during stifle extension as well as articular contact patterns (total area and areas of high contact) through the range of motion. The tibia rotated externally (P < 0.001) as the stifle was extended. Tibial abduction occurred from 110-135° of extension (P < 0.001) and tibial adduction occurred from 135° through full extension (P = 0.009). The centre of joint contact moved cranially on both tibial condyles during extension with the lateral moving a greater distance than the medial (P = 0.003). Articular contact area decreased (P = 0.001) in the medial compartment but not in the lateral compartment (P = 0.285) as the stifle was extended. The area of highest joint contact increased on the lateral tibial condyle (P < 0.001) with extension but decreased (P = 0.001) on the medial tibial condyle. Significant changes occur in tibial rotation, adduction-abduction angle and articular contact area of the equine stifle through the functional range of motion. Understanding the normal kinematics of the equine stifle and the relationship between joint positions and articular contact areas may provide important insight into the aetiology and location of common stifle joint pathologies (articular cartilage and meniscal lesions).

Comparison of Plantar Arch Index Calculated from Ink and Electronic Footprints

The general purpose of this study was to assess the accuracy of geometric characteristics of electronic footprints acquired with Zebris FDM force platform based on comparison with corresponding characteristics of conventional ink footprints. The paper presents a comparative analysis of contact areas and plantar arch index calculated from simultaneously acquired ink and electronic footprints. The areas of the three main regions of the footprints have been determined using common image processing software. The plantar arch index was calculated based on Cavanagh method. The comparative analysis evidences the differences between the geometric characteristics. The total contact area is slightly overestimated in case of the electronic footprints. The electronic footprints overestimate fore-foot and rear-foot areas and underestimate mid-foot area. The mean values of AI in case of ink footprints generally have greater values than in case of electronic footprints.

Evaluation of tribological properties of pick up roller measured using a laser microscope with a wide field of view

Analysis of contact conditions between rubber rollers and printing paper is important for stable paper feeding operation. Direct observation of apparent contact area is necessary to understand contact conditions, such as distributions of real contact area and micro-slips. However, conventional optical microscopy takes too long to observe the whole apparent contact area because the field-of-view is too narrow. We developed a wide field-of-view laser microscope, and applied it to determine the distributions of real contact area of rubber rollers against glass plates. Critical torques at which micro-slips of the rubber rollers occurred were proportional to total real contact area.

Alterations in the Plantar Pressure Patterns of Overweight and Obese Schoolchildren Due to Backpack Carriage

Among other adverse consequences, childhood obesity is known to influence foot structure and functionality. Yet little information is available regarding how the physiologic foot-ground interaction is altered when a localized load is carried, as occurs in the case of schoolbags. We investigated plantar contact area and pressure modifications induced by backpack carriage under actual conditions. We hypothesized that a localized load acting on the body would further increase the already excessive plantar pressure that exists with overweight and obese status. Seventy overweight and obese schoolchildren aged 6 to 11 years underwent two 30-sec trials on a pressure platform during a regular school day, with and without a backpack. Total and subregion contact areas along with peak plantar pressures were obtained, and results were compared with those of an equal-numbered group of normal-weight schoolchildren. Overweight and obese children generally had larger contact areas and higher peak plantar pressures compared with their normal-weight peers. In overweight and normal-weight participants, the backpack induced a similar generalized increase in contact area and pressures. However, the largest changes were observed in the forefoot, suggesting that load action tends to modify the physiologic pressure patterns. Backpack carriage raises the already elevated peak plantar pressures in overweight children during upright stance and modifies the physiologic pressure patterns. Further investigations are needed to clarify the features of such phenomenon when dynamic activities are performed and to verify the existence of fatigue and overexertion on the foot as well as other possible negative long-term effects.

Changes in Plantar Loading Based on Shoe Type and Sex During a Jump-Landing Task

Metatarsal stress fractures are common in cleated-sport athletes. Previous authors have shown that plantar loading varies with footwear, sex, and the athletic task. To examine the effects of shoe type and sex on plantar loading in the medial midfoot (MMF), lateral midfoot (LMF), medial forefoot (MFF), middle forefoot (MidFF), and lateral forefoot (LFF) during a jump-landing task. Crossover study. Laboratory. Twenty-seven recreational athletes (14 men, 13 women) with no history of lower extremity injury in the last 6 months and no history of foot or ankle surgery. The athletes completed 7 jumping trials while wearing bladed-cleat, turf-cleat, and running shoes. Maximum force, contact area, contact time, and the force-time integral were analyzed in each foot region. We calculated 2 × 3 analyses of variance (α = .05) to identify shoe-condition and sex differences. We found no shoe × sex interactions, but the MMF, LMF, MFF, and LFF force-time integrals were greater in men (P < .03). The MMF maximum force was less with the bladed-cleat shoes (P = .02). Total foot and MidFF maximum force was less with the running shoes (P < .01). The MFF and LFF maximum forces were different among all shoe conditions (P < .01). Total foot contact area was less in the bladed-cleat shoes (P = .01). The MMF contact area was greatest in the running shoes (P < .01). The LFF contact area was less in the running shoes (P = .03). The MFF and LFF force-time integrals were greater with the bladed-cleat shoes (P < .01). The MidFF force-time integral was less in the running shoes (P < .01). Independent of shoe, men and women loaded the foot differently during a jump landing. The bladed cleat increased forefoot loading, which may increase the risk for forefoot injury. The type of shoe should be considered when choosing footwear for athletes returning to activity after metatarsal stress fractures.

Improving glenoid-side load sharing in a virtual reverse shoulder arthroplasty model

The goal of glenoid fixation in reverse shoulder arthroplasty (RSA) is to provide a stable environment to allow bony ingrowth into the baseplate. When this does not occur, eventual baseplate failure is likely. This study aims to determine the additional implant-bone contact achieved when the glenosphere undersurface is in contact with the glenoid and if this increase in implant-bone contact improves stability through load sharing with respect to baseplate fixation. We hypothesize that substantial increases in contact area are possible and that this increased contact area will improve baseplate stability through load sharing. A computer-assisted design program was used to create 3-dimensional models of 7 currently available RSA devices. Total implant-bone contact area was compared in 2 conditions: (1) baseplate flush with bone and no additional glenosphere contact, or (2) baseplate and glenosphere undersurface in contact with bone. Next, finite element models were created from a commercially available system. Micromotion and stress were computed for each size of implant in the 2 conditions. All devices tested can achieve increased total contact area when the glenosphere is in contact with bone. Stress and micromotion were reduced when comparing condition 2 with condition 1 in all sizes of one commercially available system. The average micromotion decreased 37%, from 98.04 to 61.97 μm. Larger glenospheres experienced a greater reduction in micromotion. Likewise, average von Mises stress decreased 26%, from 3.29 to 2.42 MPa. Increasing glenosphere size and allowing glenosphere undersurface contact increased overall implant-bone contact area and baseplate stability.

Lipid exhange between membranes: effects of temperature and ionic strength

Transmembrane lipid exchange is critical to membrane function and pharmaceutical application. The exchange process is not fully understood and it is explored by quartz crystal microbalance with dissipation monitor method in this paper. It is found that the vesicle deformation discrepancy is not significant for the supported-lipid-bilayer-attached vesicles under different thermal and ionic strength conditions. And hence the total intermembrane contact area is determined by the vesicle adsorption amount. The maximum total intermembrane contact area decreases with the increase of temperature and the decrease of ionic strength. The changes of the vesicle adsorption rate and the transmembrane lipid exchange rate induced by temperature and ionic strength are elucidated to understand the observation above. The study helps explain some physiological phenomena and provides some guidelines for drug delivery researches.

Spinal Cord Injury and Pressure Ulcer Prevention: Using Functional Activity in Pressure Relief

Background. People with spinal cord injury (SCI) are at increased risk of pressure ulcers due to prolonged periods of sitting. Concordance with pressure relieving movements is poor amongst this population, and one potential alternative to improve this would be to integrate pressure relieving movements into everyday functional activities. Objectives. To investigate both the current pressure relieving behaviours of SCI individuals during computer use and the application of an ergonomically adapted computer-based activity to reduce interface pressure. Design. Observational and repeated measures design. Setting. Regional Spinal Cord Injury Unit. Participants. Fourteen subjects diagnosed with SCI (12 male, 2 female). Intervention.Comparing normal sitting to seated movements and induced forward reaching positions. Main Outcome Measures. Interface pressure measurements: dispersion index (DI), peak pressure index (PPI), and total contact area (CA). The angle of trunk tilt was also measured. Results. The majority of movements yielded less than 25% reduction in interface pressure compared to normal sitting. Reaching forward by 150% of arm length during an adapted computer activity significantly reduced DI (P < 0.05), angle of trunk tilt (p<0.05), and PPI for both ischial tuberosity regions (P < 0.001) compared to normal sitting. Conclusion. Reaching forward significantly redistributed pressure at the seating interface, as evidenced by the change in interface pressures compared to upright sitting.

Reliability of footprint geometric and plantar loading measurements in children using the Emed® M system

This study investigated the between-day reliability of footprint geometric and plantar loading measurements on children utilising the Emed® M pressure measurement device. Bilateral footprints (static and dynamic) and foot loading measurements using the two-step gait method were collected on 21 children two days apart (age=9.9±1.8 years; mass=34.6±8.9kg; height=1.38±0.12m). Static and dynamic footprint geometric (lengths, widths and angles) and dynamic loading (pressures, forces, contact areas and contact time) parameters were compared. Intraclass correlation coefficients of static geometric parameters were varied (0.19–0.96), while superior results were achieved with dynamic geometric (0.66–0.98) and loading variables (0.52–0.94), with the exception of left contact time (0.37). Standard error of measurement recorded small absolute disparity for all geometric (length=0.1–0.3cm; arch index=0.00–0.01; subarch angle=0.6–6.2°; left/right foot progression angle=0.5°/0.7°) and loading (peak pressure=2.3–16.2kPa; maximum force=0.3–3.0%; total contact area=0.28–0.49cm2; % contact area=0.1–0.6%; contact time=32–79ms) variables. Coefficient of variation displayed widest spread for static geometry (1.1–27.6%) followed by dynamic geometry (0.8–22.5%) and smallest spread for loading (1.3–16.8%) parameters. Limits of agreement (95%) were narrower in dynamic than static geometric parameters. Overall, the reliability of most dynamic geometric and loading parameters was good and excellent. Static electronic footprint measurements on children are not recommended due to their light body mass which results in incomplete footprints.

Predicting the density and tensile strength of viscoelastic soy powder compacts

The key physical property of compact density is important for scale up and influences the mechanical properties such as tensile strength. Hence, the objective of this research was to develop semi-mechanistic models for density of Soy Flour (SF) and Soy Protein Concentrate (SPC) powder compacts as a function of viscoelastic properties and process variables. Each of the powders was compacted at a punch speed of 5mm/min to final compaction pressures in the range of 26–230MPa, in a 13mm diameter cylindrical die. Pressure–time profile during compaction, compact height and force relaxation during the dwell time were also recorded. Compact density was measured under maximum pressure and 24h post ejection. The force relaxation data was fit to linear Maxwell model for a viscoelastic solid (R2>0.99) and the viscoelastic properties of the pure solid material were estimated by extrapolating to zero compact porosity. Although density of compacts from either powder was found to be comparable, SPC produced much stronger compacts compared to SF due to higher bonding. The estimated compact density under pressure was found to be much higher than the pycnometer measured true densities. The contact area between two particles was estimated using Lum and Duncan-Hewitt (1999) using median particle size, pressure–time during compaction and material viscoelastic properties. Power law and logarithmic models that express the compact density and tensile strength respectively as a function of total viscoelastic contact area in a compact were successfully developed (R2>0.95–0.99). Thus, viscoelastic properties were found to influence compact density and tensile strength through their influence on the contact area.

Genetic-Algorithm-Based Controlling of Microcontact Distributions to Minimize Electrical Contact Resistance

When two large conductors are in contact over a finite area, the real contact area is determined by the number of clusters of microcontacts where the positions of the clusters are determined by the large-scale waviness of the surface. In addition, the microcontacts are influenced by the small-scale surface roughness. It is widely recognized that the constriction resistance is determined partly by the number and size of the microcontacts and partly by their grouping into clusters. This paper focuses on a parameter study and on the design of the microcontact clusters in terms of the electrical contact resistance (ECR). This paper investigates the positioning and/or sizing optimization of microcontact spots in order to minimize the ECR. The optimal solutions are obtained by a novel method of a real-coded genetic-algorithm implemented with a subpopulation-based selection method and a normal-distribution-probability-based crossover. Also, this paper emphasizes the advantage of the formal optimization method when a total contact area limitation is imposed as a constraint.

Effect of Envelope Proteins on the Mechanical Properties of Influenza Virus

The envelope of the influenza virus undergoes extensive structural change during the viral life cycle. However, it is unknown how lipid and protein components of the viral envelope contribute to its mechanical properties. Using atomic force microscopy, here we show that the lipid envelope of spherical influenza virions is ∼10 times softer (∼0.05 nanonewton nm(-1)) than a viral protein-capsid coat and sustains deformations of one-third of the virion's diameter. Compared with phosphatidylcholine liposomes, it is twice as stiff, due to membrane-attached protein components. We found that virus indentation resulted in a biphasic force-indentation response. We propose that the first phase, including a stepwise reduction in stiffness at ∼10-nm indentation and ∼100 piconewtons of force, is due to mobilization of membrane proteins by the indenting atomic force microscope tip, consistent with the glycoprotein ectodomains protruding ∼13 nm from the bilayer surface. This phase was obliterated for bromelain-treated virions with the ectodomains removed. Following pH 5 treatment, virions were as soft as pure liposomes, consistent with reinforcing proteins detaching from the lipid bilayer. We propose that the soft, pH-dependent mechanical properties of the envelope are critical for the pH-regulated life cycle and support the persistence of the virus inside and outside the host.

Nanoscale investigation of AlGaN/GaN-on-Si high electron mobility transistors

AlGaN/GaN HEMTs are devices which are strongly influenced by surface properties such as donor states, roughness or any kind of inhomogeneity. The electron gas is only a few nanometers away from the surface and the transistor forward and reverse currents are considerably affected by any variation of surface property within the atomic scale. Consequently, we have used the technique known as conductive AFM (CAFM) to perform electrical characterization at the nanoscale. The AlGaN/GaN HEMT ohmic (drain and source) and Schottky (gate) contacts were investigated by the CAFM technique. The estimated area of these highly conductive pillars (each of them of approximately 20–50 nm radius) represents around 5% of the total contact area. Analogously, the reverse leakage of the gate Schottky contact at the nanoscale seems to correlate somehow with the topography of the narrow AlGaN barrier regions producing larger currents.

The Effect of Chair Designs on Sitting Pressure Distribution and Tissue Perfusion

The aim of this study was to investigate the effect of five chair designs on interface pressure distribution and tissue perfusion in the buttock-thigh region. Prolonged sitting has been found to contribute to the symptoms of work-related low back pain. Studies have found that chair design affects users' sitting posture and comfort. As sitting applies pressure to the user, it is necessary to investigate how chair design affects sitting pressure and tissue perfusion during sitting. We tested five chair designs (Suspension A, Suspension B, Foam A, Foam B, and bicompliant) on 15 young, healthy females. Sitting interface pressure and buttock-thigh tissue perfusion (in terms oftranscutaneous partial pressure of oxygen and carbon dioxide, tcPO2 and tcPCO2, respectively) were measured during 10-min sitting on each chair. We found that chair design significantly affected the distribution of the sitting pressure (p < .001) and buttock-thigh tissue perfusion (p < .023). Average pressure and total contact area were found highest in both foam designs, and the average pressure was the lowest in one of the suspension designs. Across all tested chair designs, the anterior portion of the seat sustained the lowest contact pressure. It was also found that tcPO2 was the lowest (p < .003) and tcPCO2 was the highest (p < .001) in tissue around ischial tuberosity for all chair designs. Chair design and materials of the seat significantly affect the sitting interface pressure distribution and tissue perfusion in sitting area. Further evaluation of these outcomes may provide useful information to correlate chair design with sitting comfort.

Electrochemical detection of redox species flowing in a nitrocellulose membrane and application to quantitative immunochromatography

We have demonstrated the electrochemistry of a redox active species, Fe(CN)64−, flowing in a nitrocellulose membrane incorporated into two plates with a pole array and electrodes, and applied it by measuring the activity of an enzyme, glucose oxidase (GOx), captured by immunoreaction to develop an electrochemical immunochromatographic format. The flow in the membrane between the flat surfaces with electrodes is unstable because the solution seeps into the surfaces by capillary force and the substrate support and electrode materials have different wettabilities. Thus, electrochemical responses obtained were also unstable. We prepared the small pole array and incorporated a microelectrode in a pole to diminish the total contact area used to support the membrane. The solution flowed uniformly and stably in the membrane supported on the plates with the pole array, and a steady-state oxidation current of Fe(CN)64− was observed by amperometry. The mouse IgG used as a model target was captured in the antibody immobilization area prepared in the membrane. Subsequent flowing of GOx to conjugate the antibody allowed the labeling of the captured target by the formation of a sandwich-type immunocomplex. Fe(CN)64− produced through the enzyme reaction in the presence of glucose flowed downstream to give an electrochemical response with the electrode arranged 2mm from the antibody immobilization area. Electrochemical detection of redox species flowing in the membrane indicated the possibility for developing a single-step immunochromatographic assay format with electrochemical quantitation.