Trimodal wireless intramuscular device detects muscle pressure, flow, and oxygenation changes in porcine model of lower extremity compartment syndrome.

PURPOSE: Compartment syndrome remains difficult to diagnose early in its clinical course. Pressure transducer catheters have been used to directly measure intracompartmental pressure (ICP), but this method is unreliable, with a false positive rate of 35%. We have previously used intramuscular near infrared spectroscopy to detect changes in tissue oxygen saturation (StO2) in response to increasing ICP using a novel implantable probe. However, measuring StO2 may not be sufficient to identify CS in the clinical setting. The pathophysiology of CS consists of increased ICP, leading to decreased tissue perfusion, and resulting in reduced tissue oxygenation. More clinically useful information may come from the integration of multiple data streams to aid in the diagnosis of CS. In this study, we present a novel, intramuscular probe capable of simultaneous measurement of ICP, StO2, and microvascular blood flow in a porcine model of ACS. METHODS: Proof of concept for this device is demonstrated in a porcine lower extremity balloon compression model of ACS. Pressure was maintained for 20 min (short-term) or 3 h (long-term) before the balloon volume was removed. RESULTS: In both short- and long-term experiments, as ICP increased with increasing balloon volume, the novel multimodal sensor simultaneously and reliably detected pressure elevation and corresponding reversible reductions in microvascular flow rate and tissue oxygenation. CONCLUSION: This novel trimodal device simultaneously measured the elevated ICP, decreased perfusion, and tissue ischemia of evolving ACS, substantiating our basic understanding of CS pathophysiology.

A wirelessly programmable, skin-integrated thermo-haptic stimulator system for virtual reality.

Sensations of heat and touch produced by receptors in the skin are of essential importance for perceptions of the physical environment, with a particularly powerful role in interpersonal interactions. Advances in technologies for replicating these sensations in a programmable manner have the potential not only to enhance virtual/augmented reality environments but they also hold promise in medical applications for individuals with amputations or impaired sensory function. Engineering challenges are in achieving interfaces with precise spatial resolution, power-efficient operation, wide dynamic range, and fast temporal responses in both thermal and in physical modulation, with forms that can extend over large regions of the body. This paper introduces a wireless, skin-compatible interface for thermo-haptic modulation designed to address some of these challenges, with the ability to deliver programmable patterns of enhanced vibrational displacement and high-speed thermal stimulation. Experimental and computational investigations quantify the thermal and mechanical efficiency of a vertically stacked design layout in the thermo-haptic stimulators that also supports real-time, closed-loop control mechanisms. The platform is effective in conveying thermal and physical information through the skin, as demonstrated in the control of robotic prosthetics and in interactions with pressure/temperature-sensitive touch displays.

A transient, closed-loop network of wireless, body-integrated devices for autonomous electrotherapy.

Temporary postoperative cardiac pacing requires devices with percutaneous leads and external wired power and control systems. This hardware introduces risks for infection, limitations on patient mobility, and requirements for surgical extraction procedures. Bioresorbable pacemakers mitigate some of these disadvantages, but they demand pairing with external, wired systems and secondary mechanisms for control. We present a transient closed-loop system that combines a time-synchronized, wireless network of skin-integrated devices with an advanced bioresorbable pacemaker to control cardiac rhythms, track cardiopulmonary status, provide multihaptic feedback, and enable transient operation with minimal patient burden. The result provides a range of autonomous, rate-adaptive cardiac pacing capabilities, as demonstrated in rat, canine, and human heart studies. This work establishes an engineering framework for closed-loop temporary electrotherapy using wirelessly linked, body-integrated bioelectronic devices.

Physically Detachable and Operationally Stable Cs2 SnI6 Photodetector Arrays Integrated with µ-LEDs for Broadband Flexible Optical Systems.

With the surge in perovskite research, practical features for future applications are desired to be secured, but the reliability of the materials and the use of hazardous Pb are longstanding problems. Here, an air-stable Cs2 SnI6 (CSI) is prepared via diluted hydriodic acid solvent-based precursor optimization during scalable hydrothermal growth. Materials characterization is performed using various elemental peak analyses and crystallographic identification. The resulting CSI exhibits long-term operating stability over 6 months, i) at elevated temperatures, ii) in ambient air, and iii) under light illumination from UV to near-infrared. More importantly, to demonstrate an intriguing class of applications up to system level, physically detachable CSI photodetector arrays (PD-arrays), integrated with micro-light-emitting-diodes (µ-LEDs) arrays, are successfully fabricated. In addition, 3 × 3 flexible CSI PDs are fully operational, even in air, and their spatial uniformity in pixels is quantitatively evaluated. The charge-transport mechanisms of the CSI PDs under light and elevated temperature are assessed via temperature-dependent characterization from 148 to 373 K, implying the involvement of 3D variable-range hopping. Multicycle evaluation of the CSI PD-arrays confirms their operational stability in AC and DC modes, demonstrating this platform's potential benefit for wireless optical interconnection in advanced Si technology.

Remote Recognition of Moving Behaviors for Captive Harbor Seals Using a Smart-Patch System via Bluetooth Communication.

Animal telemetry has been recognized as a core platform for exploring animal species due to future opportunities in terms of its contribution toward marine fisheries and living resources. Herein, biologging systems with pressure sensors are successfully implemented via open-source hardware platforms, followed by immediate application to captive harbor seals (HS). Remotely captured output voltage signals in real-time mode via Bluetooth communication were reproducibly and reliably recorded on the basis of hours using a smartphone built with data capturing software with graphic user interface (GUI). Output voltages, corresponding to typical behaviors on the captive HS, such as stopping (A), rolling (B), flapping (C), and sliding (D), are clearly obtained, and their analytical interpretation on captured electrical signals are fully validated via a comparison study with consecutively captured images for each motion of the HS. Thus, the biologging system with low cost and light weight, which is fully compatible with a conventional smartphone, is expected to potentially contribute toward future anthology of seal animals.