Our group measures tissue oxygenation and the cortical hemodynamic response to sensory stimuli applying continuous wave near-infrared imaging (NIRI). To improve the method's quality and applicability and to explore new fields in clinical practice and research, we developed a miniaturized wireless NIRI system. It was validated by measuring muscle oxygenation in a blood-flow occlusion experiment and brain activity in adults. Abstract: Our group measures tissue oxygenation and the cortical hemodynamic response to sensory stimuli applying continuous wave nearinfrared imaging (NIRI). To improve the method's quality and applicability and to explore new fields in clinical practice and research, we developed a miniaturized wireless NIRI system. It was validated by measuring muscle oxygenation in a blood-flow occlusion experiment and brain activity in adults. Wireless miniaturized in-vivo near infrared imaging

Biomedical sensors, integrated into textiles would enable monitoring of many vitally important physiological parameters during our daily life. In this paper we demonstrate the design and performance of a textile based pulse oximeter, operating on the forefinger tip in transmission mode. The sensors consisted of plastic optical fibers integrated into common fabrics. To emit light to the human tissue and to collect transmitted light the fibers were either integrated into a textile substrate by embroidery (producing microbends with a nominal diameter of 0.5 to 2 mm) or the fibers inside woven patterns have been altered mechanically after fabric production. In our experiments we used a two-wavelength approach (690 and 830 nm) for pulse wave acquisition and arterial oxygen saturation calculation. We have fabricated different specimens to study signal yield and quality, and a cotton glove, equipped with textile based light emitter and detector, has been used to examine movement artifacts. Our results show that textile-based oximetry is feasible with sufficient data quality and its potential as a wearable health monitoring device is promising.

We have designed a versatile, multi-channel near-infrared spectrophotometry (NIRS) instrument for the purpose of mapping neuronal activation in the neonatal and adult brain in response to motor, tactile, and visual stimulation. The optical linearity, stability, and high signal to noise ratio (>70 dB) of the instrument were demonstrated using an in vitro validation procedure. In vivo measurements on the adult forearm were also performed. Changes in oxygenation, induced by arterial occlusion of the forearm, were recorded and were shown to compare well with measurements acquired using a conventional NIRS instrument. To demonstrate the capabilities of the instrument, functional measurements in adults and neonates were performed. The instrument exhibited the capability to differentiate with a spatial resolution in the order of cm, local activation patterns associated with a finger tapping sequence.

Brain activity is associated with physiological changes, which alter the optical properties of tissue. These changes can be detected by near-infrared spectroscopy (NIRS). Aim of the study was to determine changes in cerebral oxygenation in response to stimulation in the visual cortex in newborn infants during spontaneous sleep in the first days of life. We used an in-house developed multichannel NIRS imaging instrument, the MCP-II, to measure changes in concentration of oxyhemoglobin (O(2)Hb) and deoxyhemoglobin (HHb) in specific brain areas. In 10 out of 15 subjects, a significant increase in O(2)Hb and/or a significant decrease in HHb were found in one or more channels over the occipital cortex. During stimulation, O(2)Hb increased by a mean of 0.98 mumol/l, HHb decreased by a mean 0.17 mumol/l, and total-Hb increased by a mean of 0.81 mumol/l. The hemodynamic response to visual stimulation in the occipital cortex in newborn infants is similar to adults. The increase in O(2)Hb and the simultaneous decrease in HHb during stimulation suggest an increase in cerebral blood flow (CBF) that overcompensates for the increased oxygen consumption (CMRO(2)) in the activated cortical area.

The aim of this study was to compare predictions of hyperbilirubinaemia by eye, performed by trained physicians and nurses, with predictions obtained using two commercial bilirubinometers. Jaundice was assessed in 92 white and 48 non-white healthy full-term neonates using three non-invasive methods and by total serum bilirubin as the reference method. Clinical assessment of cephalocaudal progression of jaundice was carried out independently by a physician and by nurses. Simultaneously, the Minolta Airshields JM-102 was applied on the sternum, the BiliCheck on both the forehead and the sternum, and finally, serum bilirubin concentrations were determined. The Minolta JM-102 showed the best performance with r 2 =0.90, an intraclass correlation coefficient (ICC) of 0.93, and a 95% confidence interval (CI) of ±4 units (approx. 56 lmol/l). The BiliCheck performed slightly better on the forehead than over the sternum with r 2 =0.90, an ICC of 0.88, and a CI of ±62 lmol/l. Assessment of jaundice by eye was least accurate with r 2 =0.74, an ICC of 0.67, and a CI of ±1.5 zones (corresponding to ±75 lmol/l). Skin pigmentation and ambient light both adversely affected noninvasive bilirubin estimation. Conclusion: All three non-invasive methods are well suited for estimation of serum bilirubin but show large confidence intervals. In healthy term newborns, hyperbilirubinaemia (>250 lmol/l) can be safely ruled out by eye if jaundice does not reach the abdomen or the extremities (Kramer zones 1 and 2), with <22 units (<230 lmol/l) for the Minolta JM-102, or with a cut-off of 190 lmol/l for the BiliCheck. If these respective thresholds are exceeded, serum bilirubin concentrations should be measured.

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Near-infrared spatially resolved spectroscopic quantitative measurement of liver tissue oxygenation correlates well with SvO(2) in critically ill neonates and children. Large inter-individual SvO(2) to TOI(Liver) differences may prevent its use for non-invasive single-point estimation of global tissue oxygenation. Further clinical studies are required to validate the method with other regional and global haemodynamic parameters and to evaluate its clinical use for continuous non-invasive haemodynamic monitoring.

Aim: 1) To compare the clinical assessment of craniocaudal progression of jaundice and two transcutaneous bilirubinometers with serum bilirubin values in preterm neonates; 2) to identify factors affecting the difference between non‐invasive bilirubin estimation and serum bilirubin. Methods: Serum bilirubin was clinically estimated in healthy preterm newborn infants (34 to 36.9 gestational weeks) independently by a primary investigator and by nurses, and subsequently compared with separate measures of two transcutaneous bilirubinometers. Results: A total of 107 measurements were performed on 69 infants. Minolta JM‐102 showed the best performance, with ROC area under the curve of 0.96, followed by BiliCheck™ over the sternum (0.89) and over the forehead (0.88), clinical assessment by nurses (0.73) and by a physician (0.70). Serum bilirubin <190 μmol/l can be detected with 95% sensitivity with Minolta JM–102 ≫19 units, with BiliCheck™≫145 μmol/l over the sternum and ≫165 μmol/l over the forehead and with jaundice progression to the trunk or further (Kramer zone ≫2). Gestational age affects all non‐invasive methods in the estimation of serum bilirubin, whereas skin colour affects both BiliCheck™ and clinical assessment. Ambient light affects only clinical assessment. Conclusion: Minolta JM‐102 showed the best performance, closely followed by BiliCheck™, with clinical assessment performing far worse than either transcutaneous method. None of the three methods are recommended as complete substitutes for serum bilirubin values in jaundiced preterm infants.