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Special Issue "Physiological Sensing"

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A special issue of Sensors (ISSN 1424-8220). This special issue belongs to the section "Chemical Sensors".

Deadline for manuscript submissions: closed (30 November 2007)

Special Issue Editor

Guest Editor
Dr. D. Marshall Porterfield (Website)

Purdue University, Department of Agricultural & Biological Engineering, Department of Horticulture & Landscape Architecture, Weldon School of Biomedical Engineering, 225 South University Street, W. Lafayette, IN 47907-2093, USA
Fax: +1 765 496 1115
Interests: physiological sensing; scanning probe sensor technology; biosensors; bioMEMS; bionanotechnology and lab-on-a-chip systems; bioregenerative life support systems for spaceflight (cell signaling, biophysical limitations in microgravity; nutrient delivery technology)

Special Issue Information

Physiological Sensing

Keywords

physiological sensing

Published Papers (9 papers)

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Research

Open AccessArticle Analysis of Electromyographic Signals from Rats’ Stomaches for Detection and Classification of Motility
Sensors 2008, 8(5), 2974-2985; doi:10.3390/s8052974
Received: 3 December 2007 / Accepted: 25 April 2008 / Published: 6 May 2008
PDF Full-text (267 KB) | HTML Full-text | XML Full-text
Abstract
This paper presents the analysis of the electromyographic signals from rat stomaches to identify and classify contractions. The results were validated with both visual identification and an ultrasonic system to guarantee the reference. Some parameters were defined and associated to the energy [...] Read more.
This paper presents the analysis of the electromyographic signals from rat stomaches to identify and classify contractions. The results were validated with both visual identification and an ultrasonic system to guarantee the reference. Some parameters were defined and associated to the energy of the signal in frequency domain and grouped in a P vector. The parameters were statistically analyzed and according to the results, an artificial neuronal network was designed to use the P vectors as inputs to classify the electrical signals related to the contraction conditions. A first approach classification was performed with and without contraction classes (CR and NCR), then the same database were subdivided in four classes: with induced contraction (ICR), spontaneous contraction (SCR), without contraction due a post mortem condition (PMR) or under physiological conditions (PNCR). In a two-class classifier, performance was 86%, 93% and 91% of detections for each electrogastromyografic (EGMG) signal from each of three pairs of electrodes considered. Because in the four-class classifier, enough data was not collected for the first pair, then a three-class classifier with 82% of performance was used. For the other two EGMG signals electrode pairs, performance was of 76% and 86% respectively. Based in the results, the analysis of P vectors could be used as a contraction detector in motility studies due to different stimuli in a rat model. Full article
(This article belongs to the Special Issue Physiological Sensing)
Open AccessArticle Determination of DPPH Radical Oxidation Caused by Methanolic Extracts of Some Microalgal Species by Linear Regression Analysis of Spectrophotometric Measurements
Sensors 2007, 7(10), 2080-2095; doi:10.3390/s7102080
Received: 20 June 2007 / Accepted: 1 October 2007 / Published: 3 October 2007
Cited by 55 | PDF Full-text (237 KB) | HTML Full-text | XML Full-text
Abstract
The demonstrated modified spectrophotometric method makes use of the 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical and its specific absorbance properties. Theabsorbance decreases when the radical is reduced by antioxidants. In contrast to otherinvestigations, the absorbance was measured at a wavelength of 550 nm. This wavelengthenabled [...] Read more.
The demonstrated modified spectrophotometric method makes use of the 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical and its specific absorbance properties. Theabsorbance decreases when the radical is reduced by antioxidants. In contrast to otherinvestigations, the absorbance was measured at a wavelength of 550 nm. This wavelengthenabled the measurements of the stable free DPPH radical without interference frommicroalgal pigments. This approach was applied to methanolic microalgae extracts for twodifferent DPPH concentrations. The changes in absorbance measured vs. the concentrationof the methanolic extract resulted in curves with a linear decrease ending in a saturationregion. Linear regression analysis of the linear part of DPPH reduction versus extractconcentration enabled the determination of the microalgae’s methanolic extractsantioxidative potentials which was independent to the employed DPPH concentrations. Theresulting slopes showed significant differences (6 - 34 μmol DPPH g-1 extractconcentration) between the single different species of microalgae (Anabaena sp.,Isochrysis galbana, Phaeodactylum tricornutum, Porphyridium purpureum, Synechocystissp. PCC6803) in their ability to reduce the DPPH radical. The independency of the signal on the DPPH concentration is a valuable advantage over the determination of the EC50 value. Full article
(This article belongs to the Special Issue Physiological Sensing)
Open AccessArticle Mechanosensor Channels in Mammalian Somatosensory Neurons
Sensors 2007, 7(9), 1667-1682; doi:10.3390/s7091667
Received: 10 August 2007 / Accepted: 31 August 2007 / Published: 3 September 2007
Cited by 7 | PDF Full-text (285 KB) | HTML Full-text | XML Full-text
Abstract
Mechanoreceptive sensory neurons innervating the skin, skeletal muscles andviscera signal both innocuous and noxious information necessary for proprioception, touchand pain. These neurons are responsible for the transduction of mechanical stimuli intoaction potentials that propagate to the central nervous system. The ability of [...] Read more.
Mechanoreceptive sensory neurons innervating the skin, skeletal muscles andviscera signal both innocuous and noxious information necessary for proprioception, touchand pain. These neurons are responsible for the transduction of mechanical stimuli intoaction potentials that propagate to the central nervous system. The ability of these cells todetect mechanical stimuli impinging on them relies on the presence of mechanosensitivechannels that transduce the external mechanical forces into electrical and chemical signals.Although a great deal of information regarding the molecular and biophysical properties ofmechanosensitive channels in prokaryotes has been accumulated over the past two decades,less is known about the mechanosensitive channels necessary for proprioception and thesenses of touch and pain. This review summarizes the most pertinent data onmechanosensitive channels of mammalian somatosensory neurons, focusing on theirproperties, pharmacology and putative identity. Full article
(This article belongs to the Special Issue Physiological Sensing)
Open AccessArticle Chemomechanical Polymers as Sensors and Actuators for Biological and Medicinal Applications
Sensors 2007, 7(8), 1578-1611; doi:10.3390/s7081578
Received: 8 August 2007 / Accepted: 21 August 2007 / Published: 27 August 2007
Cited by 35 | PDF Full-text (987 KB) | HTML Full-text | XML Full-text
Abstract
Changes in the chemical environment can trigger large motions in chemomechanical polymers. The unique feature of such intelligent materials, mostly in the form of hydrogels, is therefore, that they serve as sensors and actuators at the same time, and do not require [...] Read more.
Changes in the chemical environment can trigger large motions in chemomechanical polymers. The unique feature of such intelligent materials, mostly in the form of hydrogels, is therefore, that they serve as sensors and actuators at the same time, and do not require any measuring devices, transducers or power supplies. Until recently the most often used of these materials responded to changes in pH. Chemists are now increasingly using supramolecular recognition sites in materials, which are covalently bound to the polymer backbone. This allows one to use a nearly unlimited variety of guest (or effector) compounds in the environment for a selective response by automatically triggered size changes. This is illustrated with non-covalent interactions of effectors comprising of metal ions, isomeric organic compounds, including enantiomers, nucleotides, aminoacids, and peptides. Two different effector molecules can induce motions as functions of their concentration, thus representing a logical AND gate. This concept is particularly fruitful with effector compounds such as peptides, which only trigger size changes if, e.g. copper ions are present in the surroundings. Another principle relies on the fast formation of covalent bonds between an effector and the chemomechanical polymer. The most promising application is the selective interaction of covalently fixed boronic acid residues with glucose, which renders itself not only for sensing, but eventually also for delivery of drugs such as insulin. The speed of the responses can significantly increase by increasing the surface to volume ratio of the polymer particles. Of particular interest is the sensitivity increase which can be reached by downsizing the particle volume. Full article
(This article belongs to the Special Issue Physiological Sensing)
Open AccessArticle Development of a Molecularly Imprinted Biomimetic Electrode
Sensors 2007, 7(8), 1630-1642; doi:10.3390/s7081630
Received: 30 April 2007 / Accepted: 23 August 2007 / Published: 27 August 2007
Cited by 10 | PDF Full-text (439 KB) | HTML Full-text | XML Full-text
Abstract
The technique of molecular imprinting produces artificial receptor sites in apolymer that can be used in a biomimetic sensor. This research extends previous studies ofa molecularly imprinted polymer (MIP) biomimetic sensor for the small drug theophylline.The presence of theophylline in the biomimetic [...] Read more.
The technique of molecular imprinting produces artificial receptor sites in apolymer that can be used in a biomimetic sensor. This research extends previous studies ofa molecularly imprinted polymer (MIP) biomimetic sensor for the small drug theophylline.The presence of theophylline in the biomimetic sensor was monitored by analyzing thepeak currents from cyclic voltammetry experiments. The functional working range of theMIP modified electrode was 2 - 4 mM theophylline. The concentration of theophyllinethat resulted in the best signal was 3 mM. The MIP sensor showed no response to thestructurally related molecule caffeine, and therefore was selective to the target analytetheophylline. This research will provide the foundation for future studies that will result indurable biomimetic sensors that can offer a viable alternative to current sensors. Full article
(This article belongs to the Special Issue Physiological Sensing)
Open AccessArticle Proposal for an Ultrasonic Tool to Monitor the Osseointegration of Dental Implants
Sensors 2007, 7(7), 1224-1237; doi:10.3390/s7071224
Received: 21 March 2007 / Accepted: 19 June 2007 / Published: 16 July 2007
Cited by 17 | PDF Full-text (2900 KB) | HTML Full-text | XML Full-text
Abstract
The longevity of dental implants depends on osseointegration, which providesload-bearing capacity without putting the prosthesis at risk from micromotions at theimplant-bone interface. This research involved an analysis of the viability of an ultrasonicevaluation tool to quantify osseointegration. Ultrasonic transmission is directly dependenton [...] Read more.
The longevity of dental implants depends on osseointegration, which providesload-bearing capacity without putting the prosthesis at risk from micromotions at theimplant-bone interface. This research involved an analysis of the viability of an ultrasonicevaluation tool to quantify osseointegration. Ultrasonic transmission is directly dependenton the difference between the acoustic impedance of materials in intimate contact witheach other. The closer their acoustic impedances the more intense their transmission.Therefore, an analysis of the ultrasonic echoes would presumably allow for a quantitativeevaluation of the bone tissue that has grown into the pores of the implant. In addition, theliterature reports that bone fracture healing can be accelerated by the application of acontrolled low-amplitude mechanical stimulus on the site of the lesion. In fact, acousticpressure waves of low-intensity pulsed ultrasound are reportedly a secure technique forpromoting mechanical stimulus without impairing the healing process. Many experimentaland clinical trials have confirmed that daily transcutaneous ultrasound applications on theinjured site are beneficial to the enhancement of fractured bone. This proposal aims tobring together the characteristics of ultrasound propagation and the positive effect ofultrasound on bone growth into a single tool that quantitatively monitors the evolution ofthe osseointegration process. The viability of a device with these features was investigatedthrough simulations and experimentally. The initial simulations were conducted to explorethe influence of waveguide shapes on the tool’s sensitivity to changes in the implantsupporting media. The waveguides were designed in two parts, one consisting of a screw-shaped part to attach to the implant and the other a conical or step-shaped part to which the ultrasonic source was fixed in the first simulations. The step-shaped waveguide proved to be the more sensitive; intermediate stages of the osseointegration process were simulated and experiments were conducted with the step-shaped aluminum waveguide attached to a cylindrical aluminum nut embedded at different depths, so that the results obtained were only due to lateral attachment of the parts. These devices indicated that the transmission of ultrasound through the lateral surface of the implant by dilatational waves could render this tool suitable for monitoring the osseointegration of dental implants. Full article
(This article belongs to the Special Issue Physiological Sensing)
Open AccessArticle Step Prediction During Perturbed Standing Using Center Of Pressure Measurements
Sensors 2007, 7(4), 459-472; doi:10.3390/s7040459
Received: 23 February 2007 / Accepted: 13 April 2007 / Published: 18 April 2007
Cited by 2 | PDF Full-text (137 KB) | HTML Full-text | XML Full-text
Abstract
The development of a sensor that can measure balance during quiet standing and predict stepping response in the event of perturbation has many clinically relevant applica- tions, including closed-loop control of a neuroprothesis for standing. This study investigated the feasibility of an [...] Read more.
The development of a sensor that can measure balance during quiet standing and predict stepping response in the event of perturbation has many clinically relevant applica- tions, including closed-loop control of a neuroprothesis for standing. This study investigated the feasibility of an algorithm that can predict in real-time when an able-bodied individual who is quietly standing will have to make a step to compensate for an external perturbation. Anterior and posterior perturbations were performed on 16 able-bodied subjects using a pul- ley system with a dropped weight. A linear relationship was found between the peak center of pressure (COP) velocity and the peak COP displacement caused by the perturbation. This result suggests that one can predict when a person will have to make a step based on COP velocity measurements alone. Another important feature of this finding is that the peak COP velocity occurs considerably before the peak COP displacement. As a result, one can predict if a subject will have to make a step in response to a perturbation sufficiently ahead of the time when the subject is actually forced to make the step. The proposed instability detection algorithm will be implemented in a sensor system using insole sheets in shoes with minitur- ized pressure sensors by which the COPv can be continuously measured. The sensor system will be integrated in a closed-loop feedback system with a neuroprosthesis for standing in the near future. Full article
(This article belongs to the Special Issue Physiological Sensing)
Open AccessArticle Colorimetric and Fluorescent Sensing of SCN- Based on meso-Tetraphenylporphyrin/meso-Tetraphenylporphyrin Cobalt(II) System
Sensors 2007, 7(3), 410-419; doi:10.3390/s7030410
Received: 27 February 2007 / Accepted: 22 March 2007 / Published: 30 March 2007
Cited by 13 | PDF Full-text (166 KB) | HTML Full-text | XML Full-text
Abstract
An approach for colorimetric and fluorescent sensing of thiocyanate (SCN-) hasbeen proposed based on the competitive-displacement strategy betweenmeso-tetraphenylporphyrin (TPP) and meso-tetraphenylporphyrin cobalt(II) (CoTPP). InTHF-water solution, TPP emits strong fluorescence at 651 nm; however, the fluorescence wasquenched stepwise by CoTPP, and then restored [...] Read more.
An approach for colorimetric and fluorescent sensing of thiocyanate (SCN-) hasbeen proposed based on the competitive-displacement strategy betweenmeso-tetraphenylporphyrin (TPP) and meso-tetraphenylporphyrin cobalt(II) (CoTPP). InTHF-water solution, TPP emits strong fluorescence at 651 nm; however, the fluorescence wasquenched stepwise by CoTPP, and then restored by SCN-, the detection limit is 6.0 × 10-4 M.The recognition of SCN- could also be easily achieved by visual way since the assemblysystem showed significant color change by the anion. Both the fluorescence and the colorchange of the system exhibits remarkably high selectivity to SCN- over a large series ofanions. The interaction mechanisms among TPP, CoTPP and SCN- were primarilyinvestigated by fluorescence lifetime. The quenching of TPP fluorescence is attributed to theformation of TPP/CoTPP aggregates, and the fluorescence restoration is due to the binding ofCoTPP with SCN-, releasing the free TPP. This simple system has the potential to be used asa latent fluorescent sensing approach for SCN- for environmental analysis. Full article
(This article belongs to the Special Issue Physiological Sensing)
Open AccessArticle A Non-invasive and Real-time Monitoring of the Regulation of Photosynthetic Metabolism Biosensor Based on Measurement of Delayed Fluorescence in Vivo
Sensors 2007, 7(1), 52-66; doi:10.3390/s7010052
Received: 12 November 2006 / Accepted: 17 January 2007 / Published: 24 January 2007
Cited by 11 | PDF Full-text (107 KB) | HTML Full-text | XML Full-text
Abstract
In this paper, a new principle biosensor for non-invasive monitoring of theregulation of photosynthetic metabolism based on quantitative measurement of delayedfluorescence (DF) is developed. The biosensor, which uses light-emitting diode lattice asexcitation light source and a compact Single Photon Counting Module to [...] Read more.
In this paper, a new principle biosensor for non-invasive monitoring of theregulation of photosynthetic metabolism based on quantitative measurement of delayedfluorescence (DF) is developed. The biosensor, which uses light-emitting diode lattice asexcitation light source and a compact Single Photon Counting Module to collect DF signal,is portable and can evaluate plant photosynthesis capacity in vivo. Compared with itsprimary version in our previous report, the biosensor can better control environmentalfactors. Moreover, the improved biosensor can automatically complete the measurements oflight and CO2 response curves of DF intensity. In the experimental study, the testing of theimproved biosensor has been made in soybean (Glycine max Zaoshu No. 18) seedlingstreated with NaHSO3 to induce changes in seedlings growth and photosynthetic metabolism.Contrast evaluations of seedlings photosynthesis were made from measurements of netphotosynthesis rate (Pn) based on consumption of CO2 in tested plants. Current testingresults have demonstrated that the improved biosensor can accurately determine theregulatory effects of NaHSO3 on photosynthetic metabolism. Therefore, the biosensorpresented here could be potential useful for real-time monitoring the regulatory effects ofplant growth regulators (PGRs) and other exogenous chemical factors on plant growth andphotosynthetic metabolism. Full article
(This article belongs to the Special Issue Physiological Sensing)

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