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- Andersson, Peter, et al.
(author)
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Active Matrix Displays Based on All-Organic Electrochemical Smart Pixels Printed on Paper
- 2002
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In: Advanced Materials. - Weinheim, Germany : Wiley-VCH Verlagsgesellschaft. - 0935-9648 .- 1521-4095. ; 14:20, s. 1460-1464
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Journal article (peer-reviewed)abstract
- An organic electronic paper display technology (see Figure and also inside front cover) is presented. The electrochromic display cell together with the addressing electrochemical transistor form simple smart pixels that are included in matrix displays, which are achieved on coated cellulose-based paper using printing techniques. The ion-electronic technology presented offers an opportunity to extend existing use of ordinary paper.
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- Fernandes, Cláudio Pinheiro, et al.
(author)
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A Novel Sensor for Bite Force Determinations
- 2003
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In: Dental Materials. - 0109-5641 .- 1879-0097. ; 19:2, s. 118-126
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Journal article (other academic/artistic)abstract
- OBJECTIVES: The clinical usefulness, accuracy and precision of a novel bite force sensor based on force sensing resistors were tested in six subjects wearing maxillary removable partial dentures retained by conical crowns. METHODS: The surfaces of the sensor were manufactured in a silicone material that had mechanical properties similar to those of tough foodstuffs. In two separate series of standardized bite force tests, submaximum force levels were recorded with the sensor and with a strain gaged bite fork. Subjects were assisted in the loading tests with visual feedback instrumentation. Reliability estimates for the bite force sensor were calculated in order to show their reproducibility. Strain gages attached to the prostheses were used to determine the pattern of force distribution during loading tests. The bite force results obtained with the new bite force sensor and with the bite fork were analyzed with ANOVA and Scheffes tests. The strain patterns registered with strain gages were analyzed with F-test. RE-SULTS: The bite force sensor and the bite fork transducer showed no statistically significant differences in respect of intra-individual bite force levels (range 50-300N). The bite forces registered with the new sensor were dependent on the loading position (p<0.05), sex (p<0.05) and test subject (p<0.05). The reliability of the new sensor for sub-maximum bite forces was calculated to be 93%. Strain gage results showed that the new sensor generated strain patterns of less variance (p<0.05) than the bite fork and therefore allowed for higher precision during biting tests. SIGNIFICANCE: The presented instrument has such clinical merits, as to favor its use in experimental clinical studies on the biomechanics of prosthetic appliances.
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| 6. |
- Fernandes, CP, et al.
(author)
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Reflection photoelasticity: a new method for studies of clinical mechanics in prosthetic dentistry
- 2003
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In: Dental Materials. - 0109-5641 .- 1879-0097. ; 19:2, s. 106-117
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Journal article (peer-reviewed)abstract
- Objectives. This research was conducted to demonstrate the effectiveness of reflective photoelasticity as an in vivo technique for monitoring the strain/stress distribution in prosthetic devices during function. Methods. Seven subjects were selected for this study and divided into three groups according to the design of the prostheses. The buccal surfaces of the experimental prostheses were coated with a birefringent resin 2 mm thick. Using a reflection polariscope, fringe patterns were documented on video tape during standardized in vivo loadings. Strain and stress levels (gamma(max) and tau(max)) were calculated from isochromatic fringe order determinations. The intra-observer variability in counting fringe orders and the accuracy level of reflective photoelasticity as compared to strain gauge results were also studied. The strain results of in vivo loading of the prostheses were analyzed with ANOVA and Scheffes tests. The intra-observer variability was analyzed with the Friedman nonparametric test. Comparisons of photoelastic data and strain gauges were tested with Pearson's correlation. Results. Coated areas accessible to normally incident light, produced comprehensive maps of strain distribution. Significant differences were found in the in vivo gamma(max) values for the prostheses designs (p < 0.05). The test for intra-observer variability showed that no significant differences occurred in counting fringe orders. Strain values obtained with reflective photoelasticity showed a high correlation r = 0.98 and 0.99) with values obtained at the same areas using strain gauges. Significance. Reflective photoelasticity is a valid, reliable and accurate technique to be used for in vivo studies on the biomechanical behavior of prosthetic devices. (C) 2003 Academy of Dental Materials. Published by Elsevier Science Ltd. All rights reserved.
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| 7. |
- Huang, Chaorui, et al.
(author)
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Voxel- and VOI-based analysis of SPECT CBF in relation to clinical and psychological heterogeneity of mild cognitive impairment.
- 2003
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In: NeuroImage. - 1053-8119. ; 19:3, s. 1137-1144
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Journal article (peer-reviewed)abstract
- This study aimed to explore the heterogeneity of mild cognitive impairment (MCI) and detect differences in regional cerebral blood flow (rCBF) and cognitive function between progressive mild cognitive impairment (PMCI) and stable mild cognitive impairment (SMCI) in order to identify specific changes useful for early diagnosis of dementia. SPECT was performed in 82 MCI subjects and 20 controls using Tc-99m hexamethylpropyleneamine oxime. Cognitive functions were tested in five domains which included episodic memory, semantic memory, visuospatial function, attention, and general cognitive function. After the initial examination, MCI subjects were clinically followed for an average of 2 years. Twenty-eight subjects progressed to dementia and were defined as PMCI at baseline and 54 subjects remained stable and were defined as SMCI at baseline. The baseline rCBF and cognitive function of PMCI, SMCI, and controls were compared. PMCI had decreased relative rCBF in the parietal lobes and increased relative rCBF in prefrontal cortex compared to SMCI and controls at baseline. The cognitive function of PMCI was more severely impaired compared to SMCI with respect to episodic memory and visuospatial and general cognitive function. Both SPECT and neuropsychological tests had moderate discriminant function between PMCI and SMCI at baseline with the area under the receiver operating characteristic (ROC) curve at 75–77%. The combination of these two methods improved the diagnostic accuracy with the area under the ROC curve at 82–84%. Semantic memory and attention were negatively correlated with left prefrontal relative rCBF among the study population. The results show that the clinical heterogeneity of MCI is reflected in different patterns of psychological and CBF changes. Combined SPECT investigation and neuropsychological testing might predict the future development of dementia in patients with MCI.
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| 9. |
- Nilsson, David, et al.
(author)
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All-organic electrochemical device with bi-stable and dynamic functionality
- 2003
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Conference paper (other academic/artistic)abstract
- We will present organic electrochemical transistors that show both bi-stable and dynamic current modulation. In electrochemical devices, both ions and electrons are used as charge carriers. The device is all-organic and has been realized using common printing techniques, such as screen-printing. As the substrate, both cellulose-based paper and polyester foil have been used. PEDOT:PSS (poly(3,4-ethylenedioxythiophene):Poly(styrene sulphonic acid)) is used as the conducting and electrochemical active material. PEDOT:PSS is switched between different redox states, corresponding to semi-conducting and conducting states. Operating voltages is below 2V and on/off ratios up to 105 have been reached (typical value is 5000). The operation of these devices does not depend on any critical dimensions, typical dimensions used are around 200 microns. With a certain geometrical design the dynamic transistor can be employed for frequency doubling. For the bi-stable transistor the modulation of the current is done by direct electronic contact, compared to the dynamic transistor that is modulated by induction of electrochemistry. The electrolyte in these devices can either be solidified or a liquid. The bi-stable device in combination with a layer of Nafion® as electrolyte demonstrates humidity sensor functionality. Since substrates based on paper and common printing techniques can be used for fabrication, this give rise to an environmental friendly and non-expensive device setup.
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| 10. |
- Nilsson, David, et al.
(author)
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An all-organic sensor-transistor based on a novel electrochemical transducer concept printed electrochemical sensors on paper
- 2002
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In: Sensors and Actuators B: Chemical. - 0925-4005. ; 86:2-3, s. 193-197
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Journal article (peer-reviewed)abstract
- A novel transducer concept based on an organic electrochemical transistor is described. Its function as an integral part of an air humidity sensor, in which the proton conductor Nafion acts as sensitivity layer has been realised. The resulting electrochemical sensor–transistor, based on the conducting polymer PEDOT:PSS, operates at low voltages, on the order of 1 V. The sensor response, measured as the drain–source current of the electrochemical transistor, versus air humidity, has a close to exponential behaviour. The sensor can be realised using exclusively printing and coating fabrication techniques. Here, we demonstrate devices realised on plastic foils and on ordinary coated fine paper substrates. This organic electrochemical transducer promise future applications such as all-integrated low-cost sensor tags for single-use chemical sensors.
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