Medical implants, either passive implants for structural support or implantable devices with active electronics, have been widely used for the diagnosis and treatment of various diseases and clinical issues. These implants offer various functions, including mechanical support of biological structures in orthopedic and dental applications, continuous electrophysiological monitoring and feedback of electrical stimulation in neuronal and cardiac applications, and controlled drug delivery while maintaining arterial structure in drug-eluting stents. Although these implants exhibit long-term biocompatibility, surgery for their retrieval is often required, which imposes physical, biological, and economical burdens on the patients. Therefore, as an alternative to such secondary surgeries, bioresorbable implants that disappear after a certain period of time inside the body, including bioresorbable active electronics, have been highlighted recently. This review first discusses the historical background of medical implants and briefly define related terminology. Representative examples of non-degradable medical implants for passive structural support and/or for diagnosis and therapy with active electronics are also provided. Then, recent progress in bioresorbable active implants composed of biosignal sensors, actuators for therapeutics, wireless power supply components, and their integrated systems are reviewed. Finally, clinical applications of these bioresorbable electronic implants are exemplified with brief conclusion and future outlook.

https://s-space.snu.ac.kr/bitstream/10371/171737/1/RIMS91703.pdf

Bioresorbable Electronic Implants: History, Materials, Fabrication, Devices, and Clinical Applications

Development of indigenous CO2 sensing element operating at high temperature (≥ 350 °C) is highly desirable. Use of langasite (LGS) based surface acoustic wave (SAW) gas sensors is extremely beneficial compared with other commercially available sensors as it can operate at a higher temperature (> 800 °C). In the present work, we have shown CO2 sensing and its cross-sensitivity performance using LGS based SAW sensor. Compared with LGS with other sensing electrodes, calcium doped ZnO thin film (Ca_ZnO) coated LGS substrate shows enhanced CO2 sensing performance. The interdigitated electrodes (IDT) made of Pt was plated and Ca_ZnO thin film was synthesized and deposited on the LGS substrate. Additionally, we have compared the chemo-resistive gas sensing characteristics of Ca_ZnO thin film with the Ca_ZnO coated SAW sensors. Furthermore, temperature effect on CO2 sensing was studied where optimum response (change in resonant frequency ˜2.469 KHz) was observed at 400 °C. Also, the gas adsorption effect which leads to the change of the resonant frequency of the sensors has been deliberated. Besides, we have discussed the predominant effect of sensor conductivity than mass loading which enhances the reduction of the resonant frequency for thin film coated SAW sensors has been deliberated. Additionally, we have demonstrated the cross-sensitivity of H2 and CO gas in CO2 sensing and their mixed gas sensing behavior operating at 400 °C.

High temperature CO2 sensing and its cross-sensitivity towards H2 and CO gas using calcium doped ZnO thin film coated langasite SAW sensor

Simple fabrication of highly sensitive capacitive pressure sensors using a porous dielectric layer with cone-shaped patterns

/pdf/high-temperature-gas-sensors-for-harsh-environment-3qqsjk7uo4.pdf

High-Temperature Gas Sensors for Harsh Environment Applications: A Review

In this work, 2D g-C 3 N 4 nanosheets were employed as a sensitive interface for high-performance NO 2 SAW gas sensors, operating at various environmental conditions. The immense sensitivity to NO 2 gas is attributed to the enhanced mass loading effect. 

Highly sensitive g-C3N4 nanosheets as a potential candidate for the effective detection of NO2 gas via langasite-based surface acoustic wave gas sensor

Providing rapid testing and proper treatment has become highly challenging due to the rapid and highly unpredictable spread of the coronavirus disease (COVID-19). In most developing countries, rural areas lack adequate medical facilities and medical staff for effective diagnosis and treatment. Recently, there have been several technological advancements across various engineering disciplines such as the Internet of Things, unmanned aerial vehicles (UAVs) or drones, deep neural networks (DNNs), and intelligent robots. This work proposes a prototype that integrates these technologies to develop a payload deployable in a drone to help in providing rapid testing and healthcare. The proposed UAV prototype combines secure patient authentication, an automated disinfection system, and medical sensors as part of the UAV payload. It uses a DNN model for real-time COVID-19 detection. It uses intelligent flight path planning, operational management, battery recharge planning, disinfectant refilling, and strategic location planning to quickly disseminate testing kits and essential medical services to remote locations without direct human involvement.

/pdf/iomt-and-dnn-enabled-drone-assisted-covid-19-screening-and-1ani48zq3p.pdf

IoMT and DNN-Enabled Drone-Assisted Covid-19 Screening and Detection Framework for Rural Areas

This paper presents the design and testing of a new pressure sensor utilizing a doubly rotated cut piezoelectric langasite (LGS) crystal resonator with temperature compensation. The sensor can measure temperature and pressure simultaneously by using the dual mode nature of the doubly rotated cut langasite resonator (SBTC). The sensor is designed using CAD software, fabricated and tested experimentally in the laboratory for a pressure range from 0 to 45 PSI. Before fabrication the sensing principle was verified performing a force frequency analysis on the langasite resonator using a special apparatus. The experimental results on the sensor show a good linear relationship between applied pressure and C-mode frequency. Temperature compensation is also achieved by utilizing the dual mode behavior of the LGS crystal resonator. The comparison between our experiment and Peer’s theoretical modelling results shows a reasonable consistency. The sensor structure is very compact, robust, low cost and temperature compensation can be achieved at high temperatures particularly in nuclear applications.

Langasite crystal based pressure sensor with temperature compensation

Sensitivity analysis of piezo-driven stepped cantilever beams for simultaneous viscosity and density measurement

This paper presents the design, modeling, and experimental demonstration of a novel pressure sensor using an AT-cut quartz crystal resonator with beat frequency analysis-based temperature compensation technique. The combination of a compact design of the proposed pie-zoelectric crystal resonator structure and temperature compensation technique has advantages such as high accuracy, low cost, and good performance attributes. The sensor measures pressure and temperature simultaneously with a single AT-cut quartz resonator, thus avoiding the thermal lag problem in the commercial multiresonator-based pressure sensors. The pressure sensor is designed using computer-aided design software and CAE software (COMSOL Multiphysics). Finite-element analysis (FEA) of the pressure sensor is performed to analyze the stress–strain of the sensor's mechanical structure. A 3-D-printing prototype of the sensor was fabricated, and the sensing principle was verified using a force–frequency analysis apparatus. Subsequently, a full-up pressure sensor was fabricated with a stainless steel housing and a built-in crystal oscillator circuit. Based on the FEA and experimental results, we have determined that the maximum pressure the sensor can safely measure is 45 psi. Test results performed on the stainless steel product show a good linear relationship between the input (pressure) and the output (frequency).

/pdf/design-modeling-and-experiment-of-a-piezoelectric-pressure-y2bg4wadek.pdf

Sujan Yenuganti

Papers

IoMT and DNN-Enabled Drone-Assisted Covid-19 Screening and Detection Framework for Rural Areas

Langasite crystal based pressure sensor with temperature compensation

Sensitivity analysis of piezo-driven stepped cantilever beams for simultaneous viscosity and density measurement

Design, Modeling, and Experiment of a Piezoelectric Pressure Sensor Based on a Thickness-Shear-Mode Crystal Resonator

Quartz Crystal Microbalance for viscosity measurement with temperature self-compensation