Proceedings of IEEE Sensors. IEEE International Conference on Sensors最新文献

We propose a microfluidic platform with integrated microfabricated electrodes for real-time impedance profiling of transwell-based barrier models, which can be subjected to dynamic microfluidic flow. This platform overcomes the limitations of conventional methods that are based on invasive permeability assays and single time-point impedance measurements: It enables continuous, non-invasive monitoring of tissue barrier integrity at high spatial and temporal resolution. We demonstrate the capabilities of our system by continuously monitoring the gradual loss of barrier integrity in upper-airway-tissue models exposed to non-physiological liquid-liquid interface conditions.

This paper presents an extended gate field effect transistor based ion sensing platform utilizing flexible printed ion selective electrodes. A custom-printed circuit board with a Bluetooth-enabled microcontroller module enables wireless monitoring of the transistor's transfer characteristics modulated by the ion concentration in the target solution. The utilization of printing techniques such as inkjet printing and direct 3D writing provide the scope for facile and cost-effective fabrication. The system has been utilized for remote monitoring of Potassium and Ammonium ions with ideal Nernstian response, high sensitivity, and selectivity. This work provides a promising path for real-time and continuous ion monitoring which has crucial implications for health, industry, and environmental applications.

We propose a novel inexpensive embedded capacitive sensor (ECS) for sensing the shape of Continuum Dexterous Manipulators (CDMs). Our approach addresses some limitations associated with the prevalent Fiber Bragg Grating (FBG) sensors, such as temperature sensitivity and high production costs. ECSs are calibrated using a vision-based system. The calibration of the ECS is performed by a recurrent neural network that uses the kinematic data collected from the vision-based system along with the uncalibrated data from ECSs. We evaluated the performance on a 3D printed prototype of a cable-driven CDM with multiple markers along its length. Using data from three ECSs along the length of the CDM, we computed the angle and position of its tip with respect to its base and compared the results to the measurements of the visual-based system. We found a 6.6% tip position error normalized to the length of the CDM. The work shows the early feasibility of using ECSs for shape sensing and feedback control of CDMs and discusses potential future improvements.

Recent advances in remote-photoplethysmography (rPPG) have enabled the measurement of heart rate (HR), oxygen saturation (SpO₂), and blood pressure (BP) in a fully contactless manner. These techniques are increasingly applied clinically given a desire to minimize exposure to individuals with infectious symptoms. However, accurate rPPG estimation often leads to heavy loading in computation that either limits its real-time capacity or results in a costly setup. Additionally, acquiring rPPG while maintaining protective distance would require high resolution cameras to ensure adequate pixels coverage for the region of interest, increasing computational burden. Here, we propose a cost-effective platform capable of the real-time, continuous, multi-subject monitoring while maintaining social distancing. The platform is composed of a centralized computing unit and multiple low-cost wireless cameras. We demonstrate that the central computing unit is able to simultaneously handle continuous rPPG monitoring of five subjects with social distancing without compromising the frame rate and rPPG accuracy.

Existing techniques for diagnosing gastrointestinal disorders in stomach, small and large intestines, and colon depend on biopsy, endoscopy or colonoscopy methods which are invasive, expensive and time-consuming. In fact, such methods also lack the ability to access large parts of the small intestine. In this article, we demonstrate a smart ingestible biosensing capsule that is capable of monitoring pH activity in small and large intestines. pH is a known biomarker for several gastrointestinal disorders such as inflammatory bowel disease. Functionalized threads utilized as pH sensing mechanism are integrated with front-end readout electronics and 3D-printed case. This paper demonstrates a modular sensing system design that alleviates the sensor fabrication difficulties as well as the overall assembly of the ingestible capsule.

Recent advances in ingestible sensors have enabled in situ detection of gastrointestinal (GI) biomarkers which shows great potential in shifting the paradigm of diagnosing GI and systemic diseases. However, the humid, acidic gastric environment is extremely harsh to electrically powered sensors, which limits their capacity for long term, continuous monitoring. Here, we propose an encapsulation approach for a gas sensor integrated into a nasogastric (NG) tube that overcomes chemical corrosion, electrical short, and mechanical collision in a gastric environment to enable continuous gaseous biomarkers monitoring. The coating effects on the sensitivity, signal latency, and repeatability are investigated. Our long-term continuous monitoring in vitro results show that the proposed coating method enables the gas sensors to function reliably and consistently in the simulated GI environment for more than 1 week. The encapsulation is composed of Polycaprolactone (PCL) to protect against mechanical scratching and Parylene C to prevent a sensor from chemical corrosion and electrical short. The average life-time of the sensor with 10 micrometers Parylene coating is about 3.6 days. Increasing the coating thickness to 20 micrometers results in 10.0 days. In terms of repeatability, 10 micrometers and 20 micrometers Parylene C coated sensors have a standard deviation of 1.30% and 2.10% for its within sensor response, and 5.19% and 3.06% between sensors respectively.

Herein, a 60-electrode array is fabricated down the length of a microchamber for analysis of a microphysiological system. The electrode array is fabricated by standard photolithographic, metallization, and etching techniques. Permutations of 2-wire impedance measurements (10 Hz to 1 MHz) are made along the length of the microchannel using a multiplexer, Gamry potentiostat, and custom Labview code. An impedance "heat map" is created via custom algorithms. Spatial resolution and mapping capabilities are exhibited using conductive NaCl solutions and 2D cell culture.

Several models incorporate needle shape prediction, however prediction in multi-layer tissue for complex needle shape remains an issue. In this work, we present a method for trajectory generation of flexible needles that allows for complex curvatures, extending upon a previous sensor-based model. This model combines curvature measurements from fiber Bragg grating (FBG) sensors and the mechanics of an inextensible elastic rod for shape-sensing. We evaluate the method's effectiveness in single- and double-layer isotropic tissue prediction. The results illustrate a valid trajectory generation method accounting for complex curvatures in flexible needles.

Vitreoretinal surgery is among the most challenging microsurgical procedures as it requires precise tool manipulation in a constrained environment, while the tool-tissue interaction forces are at the human perception limits. While tool tip forces are certainly important, the scleral forces at the tool insertion ports are also important. Clinicians often rely on these forces to manipulate the eyeball position during surgery. Measuring sclera forces could enable valuable sensory input to avoid tissue damage, especially for a cooperatively controlled robotic assistant that otherwise removes the sensation of these familiar intraoperative forces. Previously, our group has measured sclera forces in phantom experiments. However, to the best of our knowledge, there are no published data measuring scleral forces in biological (ex-vivo/in-vivo) eye models. In this paper, we measured sclera forces in ex-vivo porcine eye model. A Fiber Bragg Grating (FBG) based force sensing instrument with a diameter of ~900 μm and a resolution of ~1 mN was used to measure the forces while the clinician-subject followed retinal vessels in manual and robot-assisted modes. Analysis of measured forces show that the average sclera force in manual mode was 133.74 mN while in robot-assisted mode was 146.03 mN.

In this work, the design, fabrication, and characterization of piezoelectric micromachined ultrasound transducer (PMUT) arrays for photoacoustic imaging applications are reported. An 80-element linear PMUT array with each element having 53 PMUT cells of 125 μm cell diameter were fabricated using 650 nm thick lead zirconate titanate (PZT) as the active piezoelectric layer. The PMUTs are designed to operate at ~10 MHz resonant frequency. The PMUT elements are validated for photoacoustic imaging using an agar gel phantom with embedded pencil leads as the imaging target. Photoacoustic A-line response of the targets captured by single PMUT element shows ~7 MHz center frequency with ~4.8 MHz bandwidth. B-mode images reconstructed from A-lines recorded during the linear scanning of a single element clearly imaged all the targets, thus validating the potential of the fabricated PMUTs for photoacoustic imaging.