Human-Inspired Tactile Perception System for Real-Time and Multimodal Detection of Tactile Stimuli.

A human can intuitively perceive and comprehend complicated tactile information because the cutaneous receptors distributed in the fingertip skin receive different tactile stimuli simultaneously and the tactile signals are immediately transmitted to the brain. Although many research groups have attempted to mimic the structure and function of human skin, it remains a challenge to implement human-like tactile perception process inside one system. In this study, we developed a real-time and multimodal tactile system that mimics the function of cutaneous receptors and the transduction of tactile stimuli from receptors to the brain, by using multiple sensors, a signal processing and transmission circuit module, and a signal analysis module. The proposed system is capable of simultaneously acquiring four types of decoupled tactile information with a compact system, thereby enabling differentiation between various tactile stimuli, texture characteristics, and consecutive complex motions. This skin-like three-dimensional integrated design provides further opportunities in multimodal tactile sensing systems.

Clinical Validation of a Wearable Piezoelectric Blood-Pressure Sensor for Continuous Health Monitoring.

Wearable blood-pressure sensors have recently attracted attention as healthcare devices for continuous non-invasive arterial pressure (CNAP) monitoring. However, the accuracy of wearable blood-pressure (BP) monitoring devices has been controversial due to the low signal quality of sensors, the absence of an accurate transfer function to convert the sensor signals into BP values, and the lack of clinical validation regarding measurement precision. Here, a wearable piezoelectric blood-pressure sensor (WPBPS) is reported, which achieves a high normalized sensitivity (0.062 kPa-1 ), and fast response time (23 ms) for CNAP monitoring. The transfer function of a linear regression model is designed, offering a simple solution to convert the flexible piezoelectric sensor signals into BP values. In order to verify the measurement accuracy of WPBPS, clinical trials are performed on 35 subjects aged from 20 to 80 s after screening. The mean difference between the WPBPS and a commercial sphygmomanometer of 175 BP data pairs is -0.89 ± 6.19 and -0.32 ± 5.28 mmHg for systolic blood pressure (SBP) and diastolic blood pressure (DBP), respectively. By building a WPBPS-embedded wristwatch, the potentially promising use of a convenient, portable, continuous BP monitoring system for cardiovascular disease diagnosis is demonstrated.

Short- and long-term mortality after intravenous thrombolysis for acute ischemic stroke: A propensity score-matched cohort with 5-year follow-up.

ABSTRACT: It remains unknown whether intravenous thrombolysis (IVT), thrombectomy, or poststroke antithrombotic medication lower short- and long-term mortality in acute ischemic stroke (AIS). This study aimed to investigate the efficacy of IVT in AIS using propensity score matching, to determine whether IVT could reduce short- and long-term mortality, and to identify risk factors influencing short- and long-term mortality in AIS.During 2013 to 2014, the nationwide Korea Acute Stroke Assessment registry enrolled 14,394 patients with first-ever recorded ischemic stroke. Propensity score matching was used to match IVT and control cases with a 1:1 ratio. The primary outcome was survival up to 3 months, 1 year, and 5 years, as assessed using Kaplan-Meier estimates and Cox proportional hazards.In total, 1317 patients treated with IVT were matched with 1317 patients not treated with IVT. Survival was higher in the IVT group (median, 3.53 years) than in the non-IVT group (median, 3.37 years, stratified log-rank test, P < .001). Compared with the non-IVT group, thrombolysis performed within 2 hours significantly reduced the risk of 3-month mortality by 37%, and thrombolysis performed between 2 and 4.5 hours significantly reduced the risk of 3-month mortality by 26%. Thrombectomy significantly reduced the risk of 3-month mortality by 28%. Compared with no poststroke medication, poststroke antiplatelet medication was associated with 51%, 55%, and 52% decreases in 3-month, 1-year, and 5-year mortality risk, respectively. Poststroke anticoagulant medication was associated with 51%, 54%, and 44% decreases in the risk of 3-month, 1-year, and 5-year mortality, respectively.IVT and mechanical thrombectomy showed improvement in short-term survival. To improve long-term outcomes, the use of poststroke antithrombotic medication is important in AIS.

Regional Differences in the Diets of Adélie and Emperor Penguins in the Ross Sea, Antarctica.

To identify the dietary composition and characteristics of both Adélie (Pygoscelis adeliae) and Emperor (Aptenodytes forsteri) penguins at four breeding sites, we performed stable carbon (δ13C) and nitrogen (δ15N) isotope analysis of down samples taken from penguin chicks. Adélie Penguin chicks at Cape Hallett mostly fed on Antarctic krill (Euphausia superba; 65.5 ± 3.5%), a reflection of the prevalence of that species near Cape Hallett, and no significant differences were noted between 2017 and 2018. However, Adélie Penguin chicks at Inexpressible Island, located near Terra Nova Bay, fed on both Antarctic silverfish (Pleuragramma antarctica; 42.5%) and ice krill (Euphausia crystallorophias; 47%), reflecting the high biomass observed in Terra Nova Bay. Meanwhile, no significant difference was noted between the two breeding sites of the Emperor Penguin. Emperor Penguin chicks predominantly fed on Antarctic silverfish (74.5 ± 2.1%) at both breeding sites (Cape Washington and Coulman Island), suggesting that diet preference represents the main factor influencing Emperor Penguin foraging. In contrast, the diet of the Adélie Penguin reflects presumed regional differences in prey prevalence, as inferred from available survey data.

Short and Long-term Outcomes of Subarachnoid Hemorrhage Treatment according to Hospital Volume in Korea: a Nationwide Multicenter Registry.

BACKGROUND: Subarachnoid hemorrhage is a potentially devastating cerebrovascular attack with a high proportion of poor outcomes and mortality. Recent studies have reported decreased mortality with the improvement in devices and techniques for treating ruptured aneurysms and neurocritical care. This study investigated the relationship between hospital volume and short- and long-term mortality in patients treated with subarachnoid hemorrhage. METHODS: We selected subarachnoid hemorrhage patients treated with clipping and coiling from March-May 2013 to June-August 2014 using data from Acute Stroke Registry, and the selected subarachnoid hemorrhage (SAH) patients were tracked in connection with data of Health Insurance Review and Assessment Service to evaluate the short-term and long-term mortality. RESULTS: A total of 625 subarachnoid hemorrhage patients were admitted to high-volume hospitals (n = 355, 57%) and low-volume hospitals (n = 270, 43%) for six months. The mortality of SAH patients treated with clipping and coiling was 12.3%, 20.2%, 21.4%, and 24.3% at 14 days, three months, one year, and five years, respectively. The short-term and long-term mortality in high-volume hospitals was significantly lower than that in low-volume hospitals. On Cox regression analysis of death in patients with severe clinical status, low-volume hospitals had significantly higher mortality than high-volume hospitals during short-term follow-up. On Cox regression analysis in the mild clinical status group, there was no statistical difference between high-volume hospitals and low-volume hospitals. CONCLUSION: In subarachnoid hemorrhage patients treated with clipping and coiling, low-volume hospitals had higher short-term mortality than high-volume hospitals. These results from a nationwide database imply that acute SAH should be treated by a skilled neurosurgeon with adequate facilities in a high-volume hospital.

Comparison of Major Clinical Outcomes between Accredited and Nonaccredited Hospitals for Inpatient Care of Acute Myocardial Infarction.

Hospital accreditation programs are used worldwide to improve the quality of care and improve patient safety. It is of great help in improving the structure of hospitals, but there are mixed research results on improving the clinical outcome of patients. The purpose of this study was to compare the levels of core clinical outcome indicators after receiving inpatient services from accredited and nonaccredited hospitals in patients with acute myocardial infarction (AMI). For all patients with AMI admitted to general hospitals in Korea from 2010 to 2017, their 30-day mortality and readmissions and length of stay were compared according to accreditation status. In addition, through a multivariate model that controls various patients' and hospitals' factors, the differences in those indicators were analyzed more accurately. The 30-day mortality of patients admitted to accredited hospitals was statistically significantly lower than that of patients admitted to nonaccredited hospitals. However, for 30-day readmission and length of stay, accreditation did not appear to yield more desirable results. This study shows that when evaluating the clinical impact of hospital accreditation programs, not only the mortality but also various clinical indicators need to be included, and a more comprehensive review is needed.

Biomimetic and flexible piezoelectric mobile acoustic sensors with multiresonant ultrathin structures for machine learning biometrics.

Flexible resonant acoustic sensors have attracted substantial attention as an essential component for intuitive human-machine interaction (HMI) in the future voice user interface (VUI). Several researches have been reported by mimicking the basilar membrane but still have dimensional drawback due to limitation of controlling a multifrequency band and broadening resonant spectrum for full-cover phonetic frequencies. Here, highly sensitive piezoelectric mobile acoustic sensor (PMAS) is demonstrated by exploiting an ultrathin membrane for biomimetic frequency band control. Simulation results prove that resonant bandwidth of a piezoelectric film can be broadened by adopting a lead-zirconate-titanate (PZT) membrane on the ultrathin polymer to cover the entire voice spectrum. Machine learning-based biometric authentication is demonstrated by the integrated acoustic sensor module with an algorithm processor and customized Android app. Last, exceptional error rate reduction in speaker identification is achieved by a PMAS module with a small amount of training data, compared to a conventional microelectromechanical system microphone.

Actuating Voltage Waveform Optimization of Piezoelectric Inkjet Printhead for Suppression of Residual Vibrations.

After a piezoelectric inkjet printhead jets the first droplet, the actuating membrane still vibrates, creating residual vibrations in the ink channel, which can degrade the inkjet printhead performance. For suppressing these vibrations, an optimized actuating voltage waveform with two pulses must be obtained, of which the first pulse is used for jetting and the second pulse is used to suppress the residual vibrations. In this study, the pressure history within the ink channel of a recirculating piezoelectric inkjet printhead was first acquired using lumped element modeling. Then, for suppressing residual vibrations, a bipolar voltage waveform was optimized via analysis of the tuning time (tt), dwell time (td2), rising time (tr2), falling time (tf2), and voltage amplitude of the second pulse. Two voltage waveforms, Waveform 01 and Waveform 02, were optimized thereafter. In Waveform 01, tt=2 µs, td2=2 µs, and tr2 and tf2=1 µswere finalized as the optimal parameters; in the case of another waveform, the optimal parameters of td2, tr2, and tf2 were found to be 4, 1, and 1 µs, respectively. The optimal voltage amplitude of the second pulse was found to be 1/3 the amplitude of the first pulse. On the basis of our analysis, the tuning time in Waveform 01 is the most sensitive parameter, and the performance yielded is even poorer than that yielded by standard waveform, if not optimized. Therefore, the other waveform is recommended for the suppression of residual vibrations.

Association between Accreditation and In-Hospital Mortality in Patients with Major Cardiovascular Diseases in South Korean Hospitals: Pre-Post Accreditation Comparison.

The direct impact of hospital accreditation on patients' clinical outcomes is unclear. The purpose of this study was to evaluate whether mortality within 30 days of hospitalization for acute myocardial infarction (AMI), ischemic stroke (IS), and hemorrhagic stroke (HS) differed before and after hospital accreditation. This study targeted patients who had been hospitalized for the three diseases at the general hospitals newly accredited by the government in 2014. Thirty-day mortality rates of three years before and after accreditation were compared. Mortality within 30 days of hospitalization for the three diseases was lower after accreditation than before (7.34% vs. 6.15% for AMI; 4.64% vs. 3.80% for IS; and 18.52% vs. 15.81% for HS). In addition, hospitals that meet the criteria of the patient care process domain have a statistically lower mortality rate than hospitals that do not. In the newly accredited Korean general hospital, it was confirmed that in-hospital mortality rates of major cardiovascular diseases were lower than before the accreditation.

Long-term Prognosis of Patients Who Contraindicated for Intravenous Thrombolysis in Acute Ischemic Stroke.

BACKGROUND: As intravenous thrombolysis (IVT) has very restricted inclusion criteria, eligible patients of IVT constitute a very small proportion and studies about their mortality are rare. The long-term mortality in a patients with contraindication of ineligible patients of IVT still under the debate. So, we investigated the proportion of patients with contraindication of IVT and the short and long-term mortality of them in AIS on emergency department comparing with the long-term effect of IVT in patients with moderate-to-severe stroke. METHODS: Using acute stroke assessment indication registry & Health Insurance Review and Assessment Service database, a total of 5,407 patients with NIHSS≥5 were selected from a total of 169 acute stroke care hospital nationwide during October-December 2011 and March-June 2013. We divided AIS patients into two groups: 1) IVT group who received IVT within 4.5 hours, and 2) non-IVT group who did not receive the IVT because of contraindications. And we divided the subgroups according to the reason of contraindication of IVT. The 5-year survival rate of each group was assessed using Kaplan-Meyer survival analysis. RESULTS: Of the 5,407 patients, a total of 1,027 (19%) patients who received IVT using r-tPA within 4.5 h after onset. Compared with the IVT group, hazard ratios of non-IVT group were 1.33 at 3 months, 1.53 at 1 year and 1.47 at 5 years (p<.001). A total of 4,380 patients did not receive IVT because of the following contraindications to IVT. 1) Time restriction: 3,378 (77.1 %) patients were admitted after 4.5 h following stroke onset, and 144 (3.3%) patients failed to determine the stroke onset time. 2) Mild symptoms:137 (3.1%) patients had rapid improvement or mild stroke on emergency room, 3) Bleeding diathesis or non-adjustable hypertension: 53 (1.2%) patients showed a bleeding tendency or severe hypertension. Compared with the IVT group, the subgroups of non-IVT group showed consistently high mortality during short and long term follow up. Mild symptom and bleeding diathesis or non-adjustable hypertension subgroup in the non-IVT group consistently showed the higher mortality than time restriction subgroup during the short and long-term follow-up (log-rank p<.001). Patients who had rapid improvement or mild stroke on emergency department had the higher mortality than time restriction group in short and long term follow up. CONCLUSION: The AIS patients with rapid improvement or mild stroke on emergency room had higher mortality than ineligible patients of IVT due to time restriction during the short and long-term follow-up. A further management and special support on emergency department is needed for these patients with initially mild stroke and rapid improvement in AIS to reduce the poor outcome.

High Resolution Micro-patterning of Stretchable Polymer Electrodes through Directed Wetting Localization.

A microarray of conducting polymer electrodes with high resolution and high pattern-fidelity is developed on a stretchable substrate through the directed wetting localization (DWL) by the differential hydrophobicity. The large difference in the surface energy between the wetting and dewetting regions serves as the major determinant of the pattern resolution and the pattern-fidelity, yielding the full surface coverage in the stretchable electrode array (SEA) with 30 µm in width. The electrical characteristics of the SEA are well preserved under different types of elastic deformations. All-solution-processed polymer light-emitting diodes (except for the cathode) based on our patterned stretchable electrodes show no appreciable degradation of the performance under stretching. The DWL provides a simple and effective way of building up diverse stretchable electrical and optoelectronic devices in advanced wearable and bio-integrated electronics.

Selective photonic printing based on anisotropic Fabry-Perot resonators for dual-image holography and anti-counterfeiting.

We present the photonic printing that can display different color images depending on the optical polarization of incident light. The dynamic selection among different images becomes possible by using anisotropic Fabry-Perot resonators that incorporate a layer of liquid crystal molecules aligned by directional molecular registration (DMR) as polarization-dependent color pixels. Using the new device platform, we demonstrate a prototype of an anticounterfeiting label with inherent anti-replicability that results from the molecular-level origin of security images. In addition, this concept is extended to polarization-selective holography. Our molecular-level approach enables to develop a new class of security labels and holographic storage media.

Modulation of surface physics and chemistry in triboelectric energy harvesting technologies.

Mechanical energy harvesting technology converting mechanical energy wasted in our surroundings to electrical energy has been regarded as one of the critical technologies for self-powered sensor network and Internet of Things (IoT). Although triboelectric energy harvesters based on contact electrification have attracted considerable attention due to their various advantages compared to other technologies, a further improvement of the output performance is still required for practical applications in next-generation IoT devices. In recent years, numerous studies have been carried out to enhance the output power of triboelectric energy harvesters. The previous research approaches for enhancing the triboelectric charges can be classified into three categories: i) materials type, ii) device structure, and iii) surface modification. In this review article, we focus on various mechanisms and methods through the surface modification beyond the limitations of structural parameters and materials, such as surficial texturing/patterning, functionalization, dielectric engineering, surface charge doping and 2D material processing. This perspective study is a cornerstone for establishing next-generation energy applications consisting of triboelectric energy harvesters from portable devices to power industries.

Antitumor effects of SB injection in canine osteosarcoma and melanoma cell lines.

The present study was designed to evaluate the effect of SB injection, which is composed of extracts from the roots of Pulsatilla koreana, Panax ginseng, and Glycyrrhiza glabra, on the viability of canine osteosarcoma and melanoma cells and nonneoplastic canine cells. Cells were treated with SB injection, conventional chemotherapeutic drugs, or a combination of both at various concentrations. Cellular viability was evaluated using a 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. Flow cytometry was used to evaluate the cell cycle and apoptosis. SB injection inhibited the growth of osteosarcoma and melanoma cells in a dose-dependent manner. The cell cycle of the affected cells was arrested in the G2/M phase, indicating an anti-proliferative effect. SB injection dose-dependently increased the rate of apoptosis. Furthermore, we found that combining SB injection with chemotherapeutic drugs resulted in a greater reduction in canine malignant cell proliferation than either treatment alone. SB injection did not affect the viability of peripheral blood mononuclear cells regardless of concentration, which suggested that SB injection did not suppress the activity of normal cells. This study suggested that SB injection can be considered an effective alternative medication for animal cancers in veterinary medicine.

Association between volume of surgery for acute hemorrhagic stroke and mortality.

This study aimed to investigate the association between volume of surgery and mortality in relation to interventions for acute hemorrhagic stroke, namely craniotomy and trephination.We obtained data on acute hemorrhagic stroke patients for a 5-year period (2009-2013) from the Health Insurance Review and Assessment Service. Hospitals were classified into 3 categories according to volume of surgery (low, medium, high). To avoid intentionally setting a cutoff, we placed the hospitals in order from those with high volume of surgery to those with low volume of surgery and divided them into 3 groups (tertile) according to the number of patients. The covariates were age, sex, hemorrhagic stroke site, type of health insurance, intensive care unit admission, history of hypertension, and Charlson comorbidity index. Multiple logistic regression analysis was performed with statistical significance set at 5%.A total of 41,917 patients who underwent craniotomy (n = 20,982) or trephination (n = 20,935) for acute hemorrhagic stroke were analyzed according to hemorrhage site (subarachnoid and others). The results showed that mortality from acute hemorrhagic stroke decreased with increasing volume of surgery. For subarachnoid hemorrhage, the odds ratios of the medium- and high-volume surgery groups were significantly lower (0.74 and 0.59, respectively) for mortality within 7 days of admission, and were also significantly lower (0.78 and 0.68) for mortality within 30 days of admission than that of the low-volume surgery group. The results for other hemorrhage sites were similar. The association between mortality and volume of surgery was more evident in the craniotomy group. Although this study was limited to a single country (South Korea), it partially addressed the shortcomings of previous studies by analyzing a nationwide database and examining all types of hemorrhagic strokes.

Generation of intensity-tunable structural color from helical photonic crystals for full color reflective-type display.

A new concept of intensity-tunable structural coloration is proposed on the basis of a helical photonic crystal (HPC). The HPCs are constructed from a mixture of chiral reactive mesogens by spin-coating, followed by the photo-polymerization. A liquid crystal (LC) layer, being homogeneously aligned, is prepared on the HPCs to serve as a tunable waveplate. The electrical modulation of the phase retardation through the LC layer directly leads to the intensity-tunable Bragg reflection from the HPCs upon the incidence of the polarized light. The bandwidths of the structural colors are found to be well preserved regardless of the applied voltage. A prototype of a full color reflective-type display, incorporated with three primary color units, is demonstrated. Our concept of decoupling two mutually independent functions, the intensity modulation by the tunable waveplate and the color reflection by the HPCs provides a simple and powerful way of producing a full color reflective-type display which possesses high color purity, high optical efficiency, the cycling durability, and the design flexibility.

Altered properties of feline adipose-derived mesenchymal stem cells during continuous in vitro cultivation.

Cytotherapy with mesenchymal stem cells (MSCs) has been studied in many species, and often requires in vitro cell expansion to obtain therapeutic doses of stem cells. Because the characteristics of MSCs, such as self-renewal and multi-lineage differentiation, can be altered by long-term culture, it is important to maintain stemness during cultivation. This study assessed the changes in the characteristics of feline adipose tissue-derived (fAT)-MSCs during in vitro passaging. Stem cells isolated from the adipose tissue of donor cats were cultured for seven sub-passages. Proliferation capacity was analyzed by calculating the cell doubling time and by colorimetric assay. Expression of stem cell-specific markers was evaluated by quantitative reverse transcription (qRT)-PCR and immunophenotyping. Expression of adipogenic and osteogenic differentiation markers was also measured by qRT-PCR. Histochemical staining and measurement of ß-galactosidase activity were conducted to detect cellular senescence. The cell proliferation rate decreased significantly at passage 5 (P5). Gene expression levels of pluripotency markers (Sox2, Nanog and Klf4) and stem cell surface markers (CD9, CD44, CD90 and CD105) decreased during continuous culture; in most assays, statistically significant changes were observed at P5. The ability of cells to undergo adipogenic or osteogenic differentiation was inversely proportional to the number of passages. The proportion of senescent cells increased with the number of passages. These results suggest that repeated passages alter the proliferation and multipotency of fAT-MSCs. In clinical trials, early-passage cells should be used to achieve the maximum therapeutic effect.

Immunomodulatory effects of soluble factors secreted by feline adipose tissue-derived mesenchymal stem cells.

Mesenchymal stem cells (MSCs) have immunomodulatory functions and differentiation capacity, and their clinical use is increasing in veterinary species. Although MSCs have been applied in the treatment in various inflammatory diseases, mechanistic research on feline MSCs is lacking. Accordingly, in this study, we aimed to investigate the immunomodulatory mechanisms of MSCs isolated from feline adipose tissue (fATMSCs). fATMSCs from healthy cats were cultured in an appropriate manner and cocultured with transwell-separated allogeneic feline peripheral blood mononuclear cells (fPBMCs) and RAW264.7 murine macrophages. After 48h of coculture, RNA was extracted from RAW264.7 cells and fPBMCs. Cytokine expression in these cells was measured using quantitative real-time polymerase chain reaction (qRT-PCR) and compared according to the presence of fATMSCs. The mRNA levels of pro-inflammatory cytokines, e.g., tumor necrosis factor-α (TNF-α), inducible nitric oxide synthase, and interleukin (IL)-1ß, were significantly decreased in cocultures of mitogen-stimulated RAW264.7 cells with fATMSCs compared with that in the RAW264.7 cells control group. Additionally, changes in the expression of mRNAs extracted from fPBMCs were as follows: pro-inflammatory TNF-α, interferon-γ, and IL-6 were decreased, and anti-inflammatory IL-10 was increased during coculture of mitogen-stimulated allogeneic fPBMCs with fATMSCs. We also extracted RNA and collected supernatants from fATMSCs during transwell culture for measurement of the expression and secretion of soluble factors by qRT-PCR and enzyme-linked immunosorbent assays, respectively. The mRNA expression of immunomodulatory factors from fATMSCs, including cyclooxygenase-2 (COX-2), transforming growth factor (TGF)-ß, indoleamine-2,3-dioxygenase (IDO) and hepatocyte growth factor, increased in the presence of RAW264.7 cells. Similarly, TGF-ß, COX-2, and IDO mRNA expression and prostaglandin E2 (PGE2) secretion from fATMSCs increased in the presence of allogeneic fPBMCs. Finally, we measured the viability of fPBMCs under various conditions. Cell viability decreased in fPBMCs suspended in fATMSC-derived conditioned medium, and this reduction was alleviated in the group supplemented with NS-398 a PGE2 inhibitor. Our data suggested that soluble factors, including PGE2, secreted by fATMSCs played an important role in the immunomodulatory effects of these cells. These findings may be helpful in the application of fATMSCs to feline patients with immune-related diseases.

Optically switchable grating based on dye-doped ferroelectric liquid crystal with high efficiency.

We demonstrate an all-optically switchable ferroelectric liquid crystal (FLC) grating constructed in an alternating binary configuration with different optical properties from domain to domain. A dye-doped FLC is uniformly aligned in one type of domains whereas it is infiltrated into the photo-polymerized networks of reactive mesogens in the other. Compared to conventional nematic LC cases, our FLC grating allows more efficient all-optical modulation and faster diffraction switching between the 0th and the 1st orders in subsecond since the optical response associated with the dye molecules in the layered state is less hindered than in the orientationally ordered state. Our dye-doped FLC grating with periodically infiltrated structures will be useful for designing a new class of all-optically switching systems.

Fabrication of human IgG sensors based on porous silicon interferometer containing Bragg structures.

A simply modified biosensor based on protein A-modified distributed Bragg reflectors (DBR) porous silicon (PSi) chip for the detection of human immunoglobin G (IgG) are developed. The fabrication, optical characterization, and surface derivatization of DBR PSi are investigated. The sensor system studied consist of multi-layer of porous silicon modified with protein-A. The sensor is operated by the measurement of the reflection peak in the white light reflection spectrum. Molecular binding is detected as a shift in wavelength of reflection peaks.