In this article, we present current methodologies, available technologies, and demands for monitoring various respiratory parameters. We discuss the importance of noninvasive techniques for remote and continuous monitoring and challenges involved in the current "smart and connected health" era. We conducted an extensive literature review on the medical significance of monitoring respiratory vital parameters, along with the current methods and solutions with their respective advantages and disadvantages. We discuss the challenges of developing a noninvasive, wearable, wireless system that continuously monitors respiration parameters and opportunities in the field and then determines the requirements of a state-of-the-art system. Noninvasive techniques provide a significant amount of medical information for a continuous patient monitoring system. Contact methods offer more advantages than non-contact methods; however, reducing the size and power of contact methods is critical for enabling a wearable, wireless medical monitoring system. Continuous and accurate remote monitoring, along with other physiological data, can help caregivers improve the quality of care and allow patients greater freedom outside the hospital. Such monitoring systems could lead to highly tailored treatment plans, shorten patient stays at medical facilities, and reduce the cost of treatment.

A wireless and battery-less trimodal neural interface system-on-chip (SoC), capable of 16-ch neural recording, 8-ch electrical stimulation, and 16-ch optical stimulation, all integrated on a 5 × 3 mm ² chip fabricated in 0.35-μm standard CMOS process. The trimodal SoC is designed to be inductively powered and communicated. The downlink data telemetry utilizes on-off keying pulse-position modulation (OOK-PPM) of the power carrier to deliver configuration and control commands at 50 kbps. The analog front-end (AFE) provides adjustable mid-band gain of 55-70 dB, low/high cut-off frequencies of 1-100 Hz/10 kHz, and input-referred noise of 3.46 μV _rms within 1 Hz-50 kHz band. AFE outputs of every two-channel are digitized by a 50 kS/s 10-bit SAR-ADC, and multiplexed together to form a 6.78 Mbps data stream to be sent out by OOK modulating a 434 MHz RF carrier through a power amplifier (PA) and 6 cm monopole antenna, which form the uplink data telemetry. Optical stimulation has a switched-capacitor based stimulation (SCS) architecture, which can sequentially charge four storage capacitor banks up to 4 V and discharge them in selected μLEDs at instantaneous current levels of up to 24.8 mA on demand. Electrical stimulation is supported by four independently driven stimulating sites at 5-bit controllable current levels in ±(25-775) μA range, while active/passive charge balancing circuits ensure safety. In vivo testing was conducted on four anesthetized rats to verify the functionality of the trimodal SoC.

The landscape of miniaturized wireless biomedical devices (MWBDs), including various injectables, ingestibles, implantables, and wearables, is rapidly expanding as proactive mobile healthcare proliferates. While the growth of MWBDs increases the flexibility of medical services, the adoption of these technologies poses privacy and security risks to their users. As a result, while being restricted in resources (size, power, processing, and storage), these devices require trust and must be at least minimally secure in the face of evolving threats. Making MWBDs secure begins with threat modeling. Therefore, this research reviews and summarizes the information on threat modeling applicable to MWBDs. Then, we propose a domain-specific qualitative-quantitative threat model that aims to help the designers and manufacturers of MWBDs to identify threats and embed security in their designs in the pre-market phase of the lifecycle of an MWBD. This model is tailored to a wide range of MWBDs. Among the different stakeholders, this model focuses on the user. It also prioritizes non-invasive direct attacks against telemetry interfaces. To discuss the advantages and disadvantages of the proposed model, it is compared to some other threat models. To illustrate how the model can be adopted by a threat-modeling team, it is then applied to representative case studies from each category of MWBDs. The outcomes of the performed risk analysis reveal that the model is easy to apply and sufficient to disclose threats.

Transcutaneous monitoring is a noninvasive method to continuously measure the partial pressures of oxygen and carbon dioxide that diffuse through the skin and correlate closely with changes in blood gases. However, the contemporary commercially available electrochemical-based technology requires a heating mechanism and a bulky, corded, and expensive sensing unit. This study aims to demonstrate a prototype noninvasive, miniaturized monitor that uses luminescence-based technology to measure the partial pressure of transcutaneous oxygen, a surrogate of the partial pressure of arterial oxygen. To be able to build a robust measurement system, we conducted experiments to understand the temperature and humidity dependence of oxygen-sensitive platinum-porphyrin films. We performed a detailed analysis of both intensity and lifetime measurement techniques. To verify the performance, we tested the prototype in a small ex-vivo experiment involving three healthy human volunteers. We measured variations in the partial pressure of transcutaneous oxygen values due to pressure-induced arterial and venous occlusions on the volunteers’ fingertips. The system resolves changes in the partial pressure of oxygen from 0 to 418 mmHg in the lab bench-top testing, covering the medically relevant range of 50-150 mmHg. Under fixed humidity, temperature, and the partial pressure of oxygen conditions, the sensor shows a 2% drift over 60 hours. The prototype consumes 9 mW of power from a 2.2 V external DC power supply.

In this paper, we present a reconfigurable rectifier, which makes it feasible to harvest energy with net-zero energy consumption, i.e. without draining power from battery, in a wide input power range. The proposed topology can operate with low input power signals and can be fine-tuned for a specific operating frequency in a wide frequency range from several MHz to GHz in remotely-powered systems. A prototype is fabricated in 0.35-μm standard CMOS process and occupies 0.019 mm2. Although the proposed rectifier supports four different rectifier topologies, on silicon it only occupies the footprint of a single rectifier. At 13.56 MHz with 2.2 mW input power, the four-switch rectifier topology yields 82% power conversion efficiency (PCE), while the hybrid topology (diodes + switches) provides 81% PCE at 11.2 mW input power. The rectifier operates with input power as low as 1.1 mW, at which level the PCE is still reasonable at 65.2%. This allows a wireless device at low power level to operate at extended read range. This reconfigurable rectifier is especially suitable for Internet of Things (IoT) mobile application, where the power of the incoming signal changes by the distance between the power source and the device.

The world has been in combat with COVID-19 since December 2019. The United States has been paralyzed, with the highest number of cases and more deaths than any other country. However, the disease has devastated almost every nation across the globe, from the Far East to Europe, Latin America, Russia, and India.