Bioimpedance measurements in dentistry to detect inflammation: numerical modelling and experimental results

Design of a Self-Measuring Device Based on Bioelectrical Impedance Analysis for Regular Monitoring of Rheumatoid Arthritis

Rheumatoid arthritis (RA) is a chronic disease, in which permanent joint deformation is largely preventable with the timely introduction of appropriate treatment strategies. However, there is no consensus for patients with RA to monitor their progress and communicate it to the rheumatologist till the condition progresses to remission. In response to this unmet need, we proposed the design of a self-measuring device based on bioelectrical impedance analysis (BIA) for regular monitoring of inflammation levels. Twenty joints of both hands were measured to monitor trends in inflammation levels. Three electrodes were used to measure two joints of each finger. A central electrode was used for two consecutive measurements. A suitable form factor for the device was proposed for the vertical placement of the hand. To ensure the stability of measurements, an air cushion was incorporated into the back of the hand, hand containers were designed on both sides, and a mobile application was designed. We conducted a convergence-assessment experiment with five air pressures to validate the consistency and convergence of bioimpedance measurements. A heuristic evaluation of the usability around the product and mobile application was conducted in parallel by six subject matter experts and validated the design. This study underscores the significance of considering patients' disease activity during intervals between hospital visits and introduces a novel approach to self-RA care.

Bioimpedance Measurement of Knee Injuries Using Bipolar Electrode Configuration

Currently, there is no suitable solution for the point-of-care diagnosis of knee injuries. A potential portable and low-cost technique for accessing and monitoring knee injuries is bioimpedance measurement. This study validated the feasibility of the bipolar electrode configuration for knee bioimpedance measurement with two electrodes placed on a fixed pair of knee acupuncture locations called Xiyan. Then, the study collected 76 valid samples to investigate the relationship between bioimpedance and knee injuries, among whom 39 patients have unilateral knee injuries, and 37 individuals have healthy knees. The self-contrast results indicated that knee injuries caused a reduction of bioimpedance of the knee by about 5% on average, which was detectable at around 100 kHz (p ≈ 0.001). Furthermore, the results analyzed by principal component analysis and support vector machines show that the detection sensitivity can reach 87.18% using the leave-one-out cross-validation. We also proposed a low-cost and portable bioimpedance measurement device that meets the needs for measuring knee joint bioimpedance.

Implantation of an Impedance Sensor for Early Detection of Gastrointestinal Anastomotic Leaks

INTRODUCTION

Accurate early diagnosis of a gastrointestinal anastomotic leak remains a challenge. When an anastomotic leak develops, the electrical properties of the tissue undergoing inflammatory processes change, resulting from the extravasation of inflammatory fluid and cellular infiltration. The method described here intends to provide a novel early anastomotic leak warning system based upon measurable changes in tissue impedance nearby an acute inflammatory process.

METHODS

A biodegradable Mg-alloy was compared with a nonabsorbable stainless steel (STS) electrode connected to a wireless recording system for impedance measurement. In vitro measurements were made in physiological solutions and small animal (eight mice) and large animal (eight pigs) models with an anastomotic leak simulated by an open colotomy. Measurements were made at 10 mm intervals from the open colon at baseline and up to 120 min comparing these with a sutured colonic wound and normal tissue.

RESULTS

In-vitro biodegradable magnesium electrode impedance evaluation showed good sensitivity to different media due to its environmental corrosion properties. The impedance of an acidic environment (1.06 ± 0.02 kΩ for citric acid) was twice that of phosphate-buffered saline (PBS) (0.64 ± 0.008 kΩ) with a distinction between Normal Saline (0.42 ± 0.013 kΩ) and PBS (0.64 ± 0.008 kΩ). This was in contrast to the performance characteristics of the control STS electrodes, where impedance in an acidic environment was lower than saline or PBS (citric acid:0.76 ± 0.01 kΩ versus PBS: 1.32 ± 0.014 kΩ). In a mouse model simulating an anastomotic leak, there was a significant increase in impedance after 120 min when compared with controls (99.7% increase versus 9.6% increase, respectively; P < 0.02). This effect was confirmed in a pig model when relative impedance measurements of the leak and control groups were compared (1.86 ± 0.46 versus 1.07 ± 0.02, respectively; P < 0.027).

CONCLUSIONS

Electrophysiological measurement shows diagnostic sensitivity for a gastrointestinal leak with potential clinical utility in the postoperative detection of early intra-abdominal sepsis. Further investigation of biodegradable tissue sensors capable of monitoring an early anastomotic leak is required.

Development of a Novel Medical Device for Mucositis and Peri-Implantitis Treatment

In spite of all the developments in dental implantology techniques, peri-implant diseases are frequent (prevalence up to 80% and 56% of subjects for mucositis and peri-implantitis, respectively) and there is an urgency for an effective treatment strategy. This paper presents an innovative electromedical device for the electromagnetic treatment of mucositis and peri-implantitis diseases. This device is also equipped with a measurement part for bioimpedance, which reflects the health conditions of a tissue, thus allowing clinicians to objectively detect impaired areas and to monitor the severity of the disease, evaluate the treatment efficacy, and adjust it accordingly. The design of the device was realized considering literature data, clinical evidence, numerical simulation results, and electromagnetic compatibility (EMC) pre-compliance tests, involving both clinicians and engineers, to better understand all the needs and translate them into design requirements. The reported system is being tested in more than 50 dental offices since 2019, providing efficient treatments for mucositis and peri-implantitis, with success rates of approximately 98% and 80%, respectively.

Electrochemical methods to enhance osseointegrated prostheses

Osseointegrated (OI) prosthetic limbs have been shown to provide an advantageous treatment option for amputees. In order for the OI prosthesis to be successful, the titanium implant must rapidly achieve and maintain proper integration with the bone tissue and remain free of infection. Electrochemical methods can be utilized to control and/or monitor the interfacial microenvironment where the titanium implant interacts with the biological system (host bone tissue or bacteria). This review will summarize the current understanding of how electrochemical modalities can influence bone tissue and bacteria with specific emphasis on applications where the metallic prosthesis itself can be utilized directly as a stimulating electrode for enhanced osseointegration and infection control. In addition, a summary of electrochemical impedance sensing techniques that could be used to potentially assess osseointegration and infection status of the metallic prosthesis is presented.