1,721,002 research outputs found
Measuring the drug absorbed by biological tissues in laboratory emulation of dermatological topical treatments
No full textAn experimental procedure for measuring the drug absorbed by a biological tissue in laboratory emulation of dermatological topical treatments is proposed. Laboratory emulation is based on the analysis of the eggplant electrical reaction to the injection of drug. Eggplant and human tissue are both well modeled by a distributed circuit model described by the ColeCole empirical equation. An exploratory measurement campaign aimed at investigating the relationship between the injected drug amount and the measured impedance is reported. The basic ideas, the measurement system design, and the proposed measurement procedure are illustrated. Then, its feasibility is proved experimentally and the results of the metrological characterization are reported and discussed. Results point out that, by a simple measurement of the impedance module (and not a spectroscopy), the amount of injected drug can be assessed by acceptable uncertainty
A Reproducible Bioimpedance Transducer for Insulin Noninvasive Measurement
Full text linkA bioimpedance transducer is proposed for noninvasive monitoring of insulin bioavailability after subcutaneous injection. The insulin bioavailability is assessed indirectly by measuring the local impedance variation due to the drug disappearance from the injection volume. The instrument allows to manage the extreme variability in insulin response by patients with diabetes due to skin conditions and/or alterations such as lipodystrophy. In this way, the transducer can also be considered as a key component for new generation of artificial pancreas. The instrument achieves the state-of-the-art accuracy and uncertainty. Intraindividual reproducibility also improved with respect to previous studies. Moreover, the feasibility of an absorption measurement is proven. After presenting the concept design and the prototype, the metrological characterization during: 1) laboratory (on passive electrical components); 2) in vitro (on eggplants); and 3) in vivo (on a human subject) experiments is reported. In laboratory tests, typical percentage deterministic errors of 1% on magnitude and phase were obtained. The mean 1- σ repeatability of 0.05% was obtained for both impedance magnitude and phase. The in vitro tests were aimed to improve the reproducibility by comparing the electrical behavior of insulin and vehicle in eggplants. During in vivo tests, a decrease in percentage 1- σ intraindividual reproducibility was reported with respect to the state-of-the-art (from more than 200% to 36%), as the impedance magnitude is concerned. In a clinical application framework, an accuracy of 9 μ l was obtained by means of a second-order polynomial model. The uncertainty was 4.2 μ l , well below the typical volume of one insulin unit (10.0 μ l)
Preliminary validation of a measurement system for emotion recognition
No full textAn highly-wearable (wireless, few-channels and dry electrodes) device is proposed for EEG based valence emotion recognition. The component is a part of an instrument for real time engagement assessment in rehabilitation 4.0. The frontal, central, and occipital asymmetry were used as well known features related to emotional valence. The device was metrologically characterized on human subjects emotionally elicited through passive viewing of pictures taken from Oasis data set. As metrological references, a standardized test, the Self Assessment Manikin, was exploited. A 2nd order polynomial kernel-based Support Vector Machine reached 83.2 ± 0.3% accuracy in classifying emotional valence from each 2-s epoch of EEG acquired signals
Wearable Brain-Computer Interface Instrumentation for Robot-Based Rehabilitation by Augmented Reality
Full text linkAn instrument for remote control of the robot by wearable brain-computer interface (BCI) is proposed for rehabilitating children with attention-deficit/hyperactivity disorder (ADHD). Augmented reality (AR) glasses generate flickering stimuli, and a single-channel electroencephalographic BCI detects the elicited steady-state visual evoked potentials (SSVEPs). This allows benefiting from the SSVEP robustness by leaving available the view of robot movements. Together with the lack of training, a single channel maximizes the device's wearability, fundamental for the acceptance by ADHD children. Effectively controlling the movements of a robot through a new channel enhances rehabilitation engagement and effectiveness. A case study at an accredited rehabilitation center on ten healthy adult subjects highlighted an average accuracy higher than 83%, with information transfer rate (ITR) up to 39 b/min. Preliminary further tests on four ADHD patients between six- and eight-years old provided highly positive feedback on device acceptance and attentional performance
High-wearable EEG-based transducer for engagement detection in pediatric rehabilitation
No full textA method for high-wearable EEG-based assessment of pediatric emotional and cognitive engagement in neuro-motor rehabilitation is proposed. A specific easy calibration is provided in the perspective of a personalized medicine. Due to the lack of studies evaluating pediatric multidimensional engagement, an observational non-interventional protocol was adopted for collecting the EEG data related to the high/low levels of engagement. The experimental validation of the proposed method involved four children performing a rehabilitation exercise in five 8-min sessions. Due to the age and frailty of the subjects, no negative emotions were expressly induced and an unbalanced dataset was obtained. Different Synthetic Minority Oversampling Technique (SMOTE)-based strategies for unbalanced dataset management and classification methods were compared. The highest performances were achieved by combining Artificial Neural Network (ANN) models with the KMeansSMOTE oversampling method. Balanced accuracies of 71.2 % and 74.5 % for the emotional engagement and the cognitive engagement are obtained, respectively
Metrological foundations of emotional valence measurement through an EEG-based system
No full textA contribution regarding the measurability of emotions and a reflection on its main related issues, are provided. The proposed use case is an electroencephalography-based detection system of positive and negative valence states. Some metrological characteristics of the proposed system were considered, i.e. reproducibility, sensitivity, and resolution. The issues concerning the measurability of emotions as lack of experimental, cross-subject, and within-subject reproducibility, as well as uncertainty induced by the adopted stimuli, were highlighted. A theoretical reference model was first identified, namely the circumplex model of affect, which is based on an interval scale. A standardized stimuli set known as Oasis was exploited. Furthermore, an initial screening of the participants was carried out to manage the bias of depressive disorders, and a compatibility analysis was conducted between the experimental sample and the sample exploited by the standardized dataset. The effectiveness of the emotion induction was maximized by choosing a polarized subset of stimuli and an implicit-more controlled mood induction procedure. A Self-Assessment Manikin was employed to verify the effectiveness of the induction procedure. The validity of the proposed method was experimentally proved. EEG signals from 25 healthy subjects were acquired through a 8-channel device. As a result, an average accuracy of 96.1 % in the within-subject case and an average accuracy equal to 80.2 % in the cross-subject case, were obtained
EEG-based detection of emotional valence towards a reproducible measurement of emotions
Full text linkA methodological contribution to a reproducible Measurement of Emotions for an EEG-based system is proposed. Emotional Valence detection is the suggested use case. Valence detection occurs along the interval scale theorized by the Circumplex Model of emotions. The binary choice, positive valence vs negative valence, represents a first step towards the adoption of a metric scale with a finer resolution. EEG signals were acquired through a 8-channel dry electrode cap. An implicit-more controlled EEG paradigm was employed to elicit emotional valence through the passive view of standardized visual stimuli (i.e., Oasis dataset) in 25 volunteers without depressive disorders. Results from the Self Assessment Manikin questionnaire confirmed the compatibility of the experimental sample with that of Oasis. Two different strategies for feature extraction were compared: (i) based on a-priory knowledge (i.e., Hemispheric Asymmetry Theories), and (ii) automated (i.e., a pipeline of a custom 12-band Filter Bank and Common Spatial Pattern). An average within-subject accuracy of 96.1 %, was obtained by a shallow Artificial Neural Network, while k-Nearest Neighbors allowed to obtain a cross-subject accuracy equal to 80.2%
Equivalent Electrical Circuit Approach to Enhance a Transducer for Insulin Bioavailability Assessment
Full text linkThe equivalent electrical circuit approach is explored to improve a bioimpedance-based transducer for measuring the bioavailability of synthetic insulin already presented in previous studies. In particular, the electrical parameter most sensitive to the variation of insulin amount injected was identified. Eggplants were used to emulate human electrical behavior under a quasi-static assumption guaranteed by a very low measurement time compared to the estimated insulin absorption time. Measurements were conducted with the EVAL-AD5940BIOZ by applying a sinusoidal voltage signal with an amplitude of 100 mV and acquiring impedance spectra in the range [1-100] kHz. 14 units of insulin were gradually administered using a Lilly's Insulin Pen having a 0.4 cm long needle. Modified Hayden's model was adopted as a reference circuit and the electrical component modeling the extracellular fluids was found to be the most insulin-sensitive parameter. The trnasducer achieves a state-of-the-art sensitivity of 225.90 ml1. An improvement of 223 % in sensitivity, 44 % in deterministic error, 7 % in nonlinearity, and 42 % in reproducibility was achieved compared to previous experimental studies. The clinical impact of the transducer was evaluated by projecting its impact on a Smart Insulin Pen for real-time measurement of insulin bioavailability. The wide gain in sensitivity of the bioimpedance-based transducer results in a significant reduction of the uncertainty of the Smart Insulin Pen. Considering the same improvement in in-vivo applications, the uncertainty of the Smart Insulin Pen is decreased from 4.2~mu l to 1.3~mu l.Clinical and Translational Impact Statement: A Smart Insulin Pen based on impedance spectroscopy and equivalent electrical circuit approach could be an effective solution for the non-invasive and real-time measurement of synthetic insulin uptake after subcutaneous administration
A micro-bioimpedance meter for monitoring insulin bioavailability in personalized diabetes therapy
No full textAn on-chip transducer, for monitoring noninvasively the insulin bio-availability in real time after administration in clinical diabetology, is proposed. The bioavailability is assessed as insulin decrease in situ after administration by means of local impedance measurement. Inter-and-intra individual reproducibility is enhanced by a personalized model, specific for the subject, identified and validated during each insulin administration. Such a real-time noninvasive bioavailability measurement allows to increase the accuracy of insulin bolus administration, by attenuating drawbacks of glycemic swings significantly. In the first part of this paper, the concept, the architecture, and the operation of the transducer, as well as details about its prototype, are illustrated. Then, the metrological characterization and validation are reported in laboratory, in vitro on eggplants, ex vivo on pig abdominal non-perfused muscle, and in vivo on a human subject, using injection as a reference subcutaneous delivery of insulin. Results of significant intra-individual reproducibility in vitro and ex vivo point out noteworthy scenarios for assessing insulin bioavailability in clinical diabetology
Enhancing inter-subject reproducibility in insulin bioavailability measurements through real-time calibration
No full textA real-time calibration to enhance the inter-subject reproducibility of insulin bioavailability measurements was proposed and validated on a diabetic patient with more than 49000 impedance values. The measurement method monitors drug absorption through a transducer consisting of a sensitive material (human abdominal tissue) and an impedance spectrometer. The in-vivo experiments revealed a statistically significant negative second-order polynomial trend in impedance magnitude corresponding to the amount of rapid-acting insulin injected. To manage the uncertainty inherent in the sensing block, the method integrates real-time calibration. Implementing a real-time calibration method based on a customized model identification at each insulin administration resulted in a reduction in deterministic error by a factor of 18. A further reduction in deterministic error for clinical application (46%) was achieved with a customized parameter second-order polynomial model with respect to the customized parameter linear model. Lastly, when less conductive long-acting insulin was administered, an increasing trend in impedance magnitude was observed, aligned with the theoretical framework of the proposed method
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