Mask-less deposition of Au-SnO2 nanocomposites on CMOS MEMS platform for ethanol detection.

Here we report on the mask-less deposition of Au-SnO2 nanocomposites with a silicon-on-insulator (SOI) complementary metal oxide semiconductor (CMOS) micro electro mechanical system (MEMS) platform through the use of dip pen nanolithography (DPN) to create a low-cost ethanol sensor. MEMS technology is used in order to achieve low power consumption, by the employment of a membrane structure formed using deep reactive ion etching technique. The device consists of an embedded tungsten micro-heater with gold interdigitated electrodes on top of the SOI membrane. The tungsten micro-heater is used to raise the membrane temperature up to its operating temperature and the electrodes are used to measure the resistance of the nanocomposite sensing layer. The CMOS MEMS devices have high electro-thermal efficiency, with 8.2 °C temperature increase per mW power of consumption. The sensing material (Au-SnO2 nanocomposite) was synthesised starting from SnO nanoplates, then Au nanoparticles were attached chemically to the surface of SnO nanoplates, finally the mixture was heated at 700 °C in an oven in air for 4 h. This composite material was sonicated for 2 h in terpineol to make a viscous homogeneous slurry and then 'written' directly across the electrode area using the DPN technique without any mask. The devices were characterised by exposure to ethanol vapour in humid air in the concentration range of 100-1000 ppm. The sensitivity varied from 1.2 to 0.27 ppm(-1) for 100-1000 ppm of ethanol at 10% relative humid air. Selectivity measurements showed that the sensors were selective towards ethanol when they were exposed to acetone and toluene.

Temperature-modulated graphene oxide resistive humidity sensor for indoor air quality monitoring.

In this paper we present a temperature-modulated graphene oxide (GO) resistive humidity sensor that employs complementary-metal-oxide-semiconductor (CMOS) micro-electro-mechanical-system (MEMS) micro-hotplate technology for the monitoring and control of indoor air quality (IAQ). GO powder is obtained by chemical exfoliation, dispersed in water and deposited via ink-jet printing onto a low power micro-hotplate. Atomic force microscopy (AFM) and transmission electron microscopy (TEM) show the typical layered and wrinkled morphology of the GO. Raman spectroscopy, X-ray photoelectron spectroscopy (XPS) and Fourier transform infra-red (FTIR) spectroscopy indicate that the GO flakes possess a significant number of oxygen containing functional groups (epoxy, carbonyl, hydroxyl) extremely attractive for humidity detection. Electro-thermal characterisation of the micro-hotplates shows a thermal efficiency of 0.11 mW per °C, resulting in a sensor DC power consumption of only 2.75 mW at 50 °C. When operated in an isothermal mode, the sensor response is detrimentally affected by significant drift, hysteretic behaviour, slow response/recovery times and hence poor RH level discrimination. Conversely, a temperature modulation technique coupled with a differential readout methodology results in a significant reduction of the sensor drift, improved linear response with a sensitivity of 0.14 mV per %, resolution below 5%, and a maximum hysteresis of ±5%; response and recovery times equal to 189 ± 49 s and 89 ± 5 s, respectively. These performance parameters satisfy current IAQ monitoring requirements. We have thus demonstrated the effectiveness of integrating GO on a micro-hotplate CMOS-compatible platform enabling temperature modulation schemes to be easily applied in order to achieve compact, low power, low cost humidity IAQ monitoring.

CMOS integration of inkjet-printed graphene for humidity sensing.

We report on the integration of inkjet-printed graphene with a CMOS micro-electro-mechanical-system (MEMS) microhotplate for humidity sensing. The graphene ink is produced via ultrasonic assisted liquid phase exfoliation in isopropyl alcohol (IPA) using polyvinyl pyrrolidone (PVP) polymer as the stabilizer. We formulate inks with different graphene concentrations, which are then deposited through inkjet printing over predefined interdigitated gold electrodes on a CMOS microhotplate. The graphene flakes form a percolating network to render the resultant graphene-PVP thin film conductive, which varies in presence of humidity due to swelling of the hygroscopic PVP host. When the sensors are exposed to relative humidity ranging from 10-80%, we observe significant changes in resistance with increasing sensitivity from the amount of graphene in the inks. Our sensors show excellent repeatability and stability, over a period of several weeks. The location specific deposition of functional graphene ink onto a low cost CMOS platform has the potential for high volume, economic manufacturing and application as a new generation of miniature, low power humidity sensors for the internet of things.

Growth of carbon nanotubes on fully processed silicon-on-insulator CMOS substrates.

This paper describes the growth of Carbon Nanotubes (CNTs) both aligned and non-aligned on fully processed CMOS substrates containing high temperature tungsten metallization. While the growth method has been demonstrated in fabricating CNT gas sensitive layers for high temperatures SOI CMOS sensors, it can be employed in a variety of applications which require the use of CNTs or other nanomaterials with CMOS electronics. In our experiments we have grown CNTs both on SOI CMOS substrates and SOI CMOS microhotplates (suspended on membranes formed by post-CMOS deep RIE etching). The fully processed SOI substrates contain CMOS devices and circuits and additionally, some wafers contained high current LDMOSFETs and bipolar structures such as Lateral Insulated Gate Bipolar Transistors. All these devices were used as test structures to investigate the effect of additional post-CMOS processing such as CNT growth, membrane formation, high temperature annealing, etc. Electrical characterisation of the devices with CNTs were performed along with SEM and Raman spectroscopy. The CNTs were grown both at low and high temperatures, the former being compatible with Aluminium metallization while the latter being possible through the use of the high temperature CMOS metallization (Tungsten). In both cases we have found that there is no change in the electrical behaviour of the CMOS devices, circuits or the high current devices. A slight degradation of the thermal performance of the CMOS microhotplates was observed due to the extra heat dissipation path created by the CNT layers, but this is expected as CNTs exhibit a high thermal conductance. In addition we also observed that in the case of high temperature CNT growth a slight degradation in the manufacturing yield was observed. This is especially the case where large area membranes with a diameter in excess of 500 microns are used.

Activated sludge is a potential source for production of biodegradable plastics from wastewater.

Increased utilization of synthetic plastics caused severe environmental pollution due to their non-biodegradable nature. In the search for environmentally friendly materials to substitute for conventional plastics, different biodegradable plastics have been developed by microbial fermentations. However, limitations of these materials still exist due to high cost. This study aims at minimization of cost for the production of biodegradable plastics P(3HB) and minimization of environmental pollution. The waste biological sludge generated at wastewater treatment plants is used for the production of P(3HB) and wastewater is used as carbon source. Activated sludge was induced by controlling the carbon: nitrogen ratio to accumulate storage polymer. Initially polymer accumulation was studied by using different carbon and nitrogen sources. Maximum accumulation of polymer was observed with carbon source acetic acid and diammonium hydrogen phosphate (DAHP) as nitrogen source. Further studies were carried out to optimize the carbon: nitrogen ratios using acetic acid and DAHP. A maximum of 65.84% (w/w) P(3HB) production was obtained at C/N ratio of 50 within 96 hours of incubation.

"Sporotrichoid nerve abscess".

Unusual presentation of a BT leprosy patient with multiple nerve abscess and an approach to diagnosis and management of the problem have been described. The article will refamiliarize the reader with unusual nature of presentation, diagnosis and management of nerve abscess associated with leprosy.

Short term chemotherapy of paucibacillary leprosy.

Twenty freshly diagnosed, previously untreated, adult male patients with paucibacillary leprosy were treated with Multi drug therapy (MDT) according to WHO regimen (1982). The patients remained in the hospital throughout the course of the study. At the end of six months treatment, they were evaluated clinicobacteriologically and histologically for evidence of the disease activity. Active disease was present in 55% of the patients at the end of six months treatment. DDS had to be discontinued in one patient who developed hepatitis.

Family studies on hanseniasis cases.

Examination of intrafamilial contacts among the first degree relatives of 400 hanseniasis patients, revealed an additional 101 cases. Distribution pattern of disease types detected in the contacts, in relation to that found in the index cases, are analysed. An attempt has been made to evaluate the role of genetic factor in determining the type of hanseniasis in a patient.

Clinical epidemiology of non-lepromatous leprosy among service personnel.

Some aspects of clinical and epidemiological presentation of 172 non-lepromatous leprosy patients, belonging to the Armed Forces of India, have been presented. Tuberculoid type (TT) was the commonest form of the disease. Majority of the patients (59.8%) had a single lesion at the time of diagnosis. Age of onset of 62.2% of the patients was between 20 and 29 years. Incidence of gross neurological deficit or deformity was rather low in these patients. Ulnar nerve involvement showed evidence of clinical symptom most often.

Family studies on hanseniasis cases.

O exame de contatos intrafamiliares entre parentes de 1o. grau de 400 pacientes de hanseniase revelou 101 casos adicionais.Sao analisados os modelos de distribuicao dos tipos de hanseniase observados nos contatos em relacao aqueles encontrados nos casos "index". Fez-se uma tentativa para avaliar os fatores geneticos na determinacao dos tipos de hanseniase em um paciente

Genetic diathesis for leprosy.

Innate incapacity to elaborate a protective cellular immunity has been thought to underlie the evaluation of the disease process of lepromatous leprosy. Although both family and twin studies were suggestive of the involvement of some genetic factors, they have so far not been evaluated fully. Keeping this in view, the present study, conducted at the family level, was designed to evaluate the role of genetic factors in determining the type of leprosy in a patient.

Dermatophyte infection of the penis. Association with a particular undergarment.

Penile involvement was seen in 19.5% of 261 patients, aged 11 to 30 years, with tinea cruris. It was more common in patients under the age of 20 years (p less than 0.05). The increased incidence is probably related to the use of langota, a semiocclusive undergarment that may favor the growth of dermatophytes.

Age of onset of leprosy.

Age of onset of leprosy is merely a subjective information based upon the memory, intelligent appreciation and awareness of the patient and his relatives, in absence of a more reliable method. In the present study, a modification of the conventional method which we named "Complemented recall" method was adopted to determine the age of onset of 400 leprosy patients, in an attempt to collect a better approximate data.

Clofazimine in Vitiligo.

Eleven patients with vitiligo were treated with clofazimine, for a period of 3 months. There was no evidence of repigmentation of the affected areas in any of the patients treated. Exposure, to sunlight in addition, did not improve the response.

Paratesticular rhabdomyosarcomas and leiomyosarcomas: a clinicopathological review.

One case of embryonal paratesticular sarcoma and 2 cases of leiomyosarcomas are reported. The 13-year-old boy with embryonal sarcoma is well after an orchiectomy and high ligation of the spermatic cord followed by radiotherapy and chemotherapy. A 66-year-old man has been doing well after orchiectomy and hemiscrotectomy for a paratesticular leiomyosarcoma. The third patient had a highly pleomorphic leiomyosarcoma and died 2 months postoperatively. The clinical and histological diagnosis of paratesticular rhabdomyosarcomas and leiomyosarcomas is reviewed and the various therapeutic approaches to these neoplasms are discussed. Retroperitoneal lymph node dissection, radiotherapy and chemotherapy are important adjuncts to orchiectomy in the management of rhabdomyosarcomas. On the contrary, retroperitoneal lymph node dissection and radiotherapy are not indicated in leiomyosarcomas, since these neoplasms tend to metastasize by the hematogenous route and are radioresistant. At the present time we are unable to evaluate chemotherapy in the management of paratesticular leiomyosarcomas.