Inkjet-printed sub-zero temperature sensor for real-time monitoring of cold environments.

Real-time monitoring of low temperatures (usually below 0 °C) or cold environments is a specific requirement that finds its high demand in the aerospace, pharmaceutical, food, and beverage industries to maintain the temperature at high altitudes or in refrigerators and cold storage. In general, this purpose is achieved by using a sub-zero temperature sensor coupled with a control system. However, the market available such temperature sensors are very expensive, and bulky, thus not being suitable for portable operation, and also they suffer from poor accuracy. Therefore, the development of high-performance, low-cost, lightweight, and portable sub-zero temperature sensors is highly desired. In our recent work, we developed such sensors and integrated them with auxiliary electronics to demonstrate their wireless operation for the continuous and real-time monitoring of cold environments. So, in order to obtain low-cost sensors a cost-effective inkjet printing technology was employed for the fabrication of devices. A lightweight polydimethylsiloxane (PDMS) was used as the substrate and an electrically conducting graphene nanocomposite was used as the temperature-sensing material. To obtain a functional graphene nanocomposite film with a thickness of 530 nm and a conductivity of ~189 S m-1, the printed graphene nanocomposite was photonically sintered using a xenon flash lamp. This step was crucial for obtaining a sensor on the soft PDMS platform. The graphene nanocomposite film exhibited a positive temperature coefficient resistance value of approximately 0.119 %/°C, and its resistance values varied almost linearly (with an Adjusted R2 value (model accuracy) of 0.99) with temperature within the operating range of -30 °C to 80 °C. The sensor was properly encapsulated for protection without significantly affecting its performance. The sensors demonstrated sufficient flexibility, with a bending radius of 20 mm, and sustained 500 continuous bending cycles. Finally, the real-time operation of the sensors was demonstrated by wirelessly transmitting and monitoring the temperature over a smartphone platform.

Popliteal artery thrombosis as a rare complication of paroxysmal nocturnal hemoglobinuria (PNH): A case report.

INTRODUCTION AND IMPORTANCE: Popliteal artery thrombosis a rare but life-threatening complication of Paroxysmal Nocturnal Hemoglobinuria caused due to hemolysis. Complications of further thrombotic event are common after initial management. CASE PRESENTATION: A 38 years old male, known case of PNH for 2 years, presented with the history of loss of pain sensation, coldness and loss of movement in left lower leg for 5 days and history of multiple blood transfusion. The patient underwent knee amputation because of possible complication of PNH. CLINICAL DISCUSSION: Intermittent claudication along with paresthesia, lower extremity weakness, stiffness, and cool extremities are seen in patients of Peripheral Artery Disease. Ultrasound color duplex is a sensitive and specific examination for peripheral flow while gold standard techniques like MRI and CT angiogram to detect and diagnose arterial lesions. CONCLUSION: The risk of thrombo-embolism in a patient of PNH should be considered by a treating doctor while early imaging and management should be done to reduce the complications and risk of amputation.

Fabrication of a reversible thermochromism based temperature sensor using an organic-inorganic composite system.

Temperature is considered a crucial physical parameter for several applications ranging from our day to day life to industrial applications. Studies have been reported to monitor the temperature by using various methods. Here, the present study demonstrates the fabrication of a simple and inexpensive temperature sensor based on the phenomenon of thermochromism, that is, the temperature can be monitored by the visual change in the sensor's color without using any additional circuitry. The mechanism of color change is associated with the difference in the coordination number of the complex compound due to the loss of crystal water in the organic-inorganic composite system. The screen printing process has been used to fabricate thin films of varying compositions in order to optimize the thermochromism in the temperature range of interest. Moreover, the reversibility of the color with a decrease in temperature allows the reusability and longevity of the sensor thus developed.