Real-time Pressure Measurement Research Articles

Novel Real-time Digital Pressure Sensor Reveals Wide Variations in Current Nerve Crush Injury Models.

Peripheral nerve crush injury (PNCI) models are commonly used to study nerve damage and the potential beneficial effects of novel therapeutic strategies. Current models of PNCI rely on inter-device and operator precision to limit the variation with applied pressure. Although the inability to accurately quantify the PNCI pressure may result in reduced reproducibility between animals and studies, there is very limited information on the standardization and quantification of applied pressure with PNCI. To address this deficit, we constructed a novel device comprised of an Arduino UNO microcontroller board and Force Sensitive Resistor capable of reporting the real-time pressure applied to a nerve. Two forceps and two needle drivers were used to perform 30-second PNCIs to the sciatic nerves of mice (n = 5/group). Needle drivers were set to the first notch, and a jig was used to hold the forceps pinch at a reproducible pressure. The Force Sensitive Resistor was interposed in-series between the nerve and instrument during PNCI. Data collected from these procedures displayed average needle driver pressures an order of multitude greater than forceps pressures. Additionally, needle driver inter- and intra-procedure pressure remained more consistent than forceps pressure, with needle driver coefficient of variation equal to 14.5% vs. a forceps coefficient of variation equal to 45.4%. This is the first demonstration of real-time pressure measurements in PNCI models and it reveals that the applied pressures are dependent on the types of device used. The large disparity in pressure represents an inability to apply graded accurate and consistent intermediate pressure gradients in PNCI. These findings indicate a need for documentation of pressure severity as a screening for PNCI in animals, and the real-time pressure sensor could be a useful tool in monitoring and applying consistent pressure, reducing the outcome variability within the same experimental model of PNCI.

A flexible microfluidic sensor based on main-channel and branch-channels for aerodynamic pressure measurement

Aerodynamic pressure distribution on the surface of aircraft is the main basis for aerodynamic shape design. According to the aerodynamic pressure distribution, the minimum pressure position, the shake wave position and the air separation on the surface of aircraft can be determined, which is of great importance to the aircraft design. In this paper, a flexible microfluidic sensor for aerodynamic pressure measurement is developed. The sensor consists of a flexible substrate with cavities, conductive liquid and electrodes. The cavities in flexible material include two parts, one is the main channel and the other is the branch channel. When external pressure is applied on the sensor, the main channel will be deformed and the conductive liquid in the main channel is forced into the branch channels, which causes the resistance change of the sensor. When external pressure is released, the main channel returns to its initial shape, and the conductive liquid in branch channels will return to main channel due to the capillary force between the conductive liquid and the flexible substrate. The preliminary experimental results demonstrate that the main channel-branch channels design can improve the sensitivity of the sensor up to 2.15× 10−2 kPa−1, and it can also avoid the leakage of conductive liquid. The developed sensor also exhibits fast dynamic response (29 ms), excellent cyclic loading/unloading stability (> 100 cycles). Moreover, experiments are also conducted to investigate the influence of the temperature and humidity. The flexible sensor brings a new opportunity for real-time aerodynamic pressure measurement due to its minor size, high sensitivity, durability and flexibility.

Mechanical Overloading Induces Articular Subchondral Bone Resorption <i>via</i> the RANTES-CCRs-Akt2 Axis

Background: Early-stage osteoarthritis (OA) is characterized by articular subchondral bone resorption and emerging evidence suggests that mechanical overloading is likely involved. Here, we identified whether and why mechanical overloading could trigger subchondral bone resorption in early-stage OA. Methods: A new mechanical overloading monitoring system for real-time pressure measurement in situ in vivo and a numerically controlled loading device for tissue pressurized culture in vitro were developed. Micro-CT was used to analyze the alterations of microarchitecture in subchondral bone and TRAP staining was harnessed to measure osteoclast differentiation of macrophages. Real-time qPCR, Western blot, ELISA, and immunostaining were conducted to clarify the expression, location, and interaction of relative proteins. Findings: Temporomandibular joint disc displacement yielded about 5 times higher pressure on the articular surface than that of the controls, causing subchondral bone resorption in 3-7 days after disc displacement. RANTES was increased in synovial fluid in early-stage OA in human and expressed in condylar cartilage of rat OA model at 1 week after disc displacement. Mechanistically, RANTES could promote osteoclast recruitment and formation through binding to its receptors CCRs and activating Akt2 pathway. Either Blockade of CCRs or Knockdown of Akt2 rescued RANTES-mediated osteoclast differentiation in vitro . Knockdown of Akt2 prevented the early subchondral bone resorption in OA in vivo. Interpretation: This study unravels a novel mechanism that disc displacement-induced mechanical overloading activates the RANTES-CCRs-Akt2 axis, which plays a critical initial role for the early condylar bone resorption in OA. Funding Information: This work was supported by grants from the National Natural Science Foundation of China (82170979, 81970920, 81772873). Declaration of Interests: The authors declare no conflict of interest. Ethics Approval Statement: The approval of synovial fluid experimentations was obtained from the Biomedical Institutional Review Board of the Peking University School and Hospital of Stomatology (PKUSSIRB-201947100), and written informed consents were attained from all participants. The approval of animal studies was obtained from the Peking University Animal Ethics Committee (LA2019310).

An Open-Globe Porcine Injury Platform for Assessing Therapeutics and Characterizing Biological Effects.

Open-globe injuries can result in permanent vision loss, partly due to extended delays between injury and medical intervention. Even with early intervention, the management of open-globe injuries remains a challenge for ophthalmologists, mostly due to inadequate or suboptimal current therapies. To aid in the development of novel therapeutics and track toxicological and pathophysiological changes, this article details an open-globe injury platform capable of inducing injuries in enucleated porcine eyes. The injury platform relies on a high-speed solenoid device to mimic explosive injury scenarios, allowing for large, complex injury shapes and sizes that are often observed in casualties and are more difficult to treat. The system can be implemented with precise computer control of the injury mechanism to allow for more complex setups. Also, the system can make use of real-time intraocular pressure measurement to track changes during injury induction and to assess therapeutic efficacy for restoring intraocular pressure and the integrity of the eye. These protocols will assist with implementation of the injury model in prospective laboratories seeking to develop therapeutics or studying biological changes that occur from this type of traumatic injury. Published 2020. U.S. Government. Basic Protocol 1: Preparing gelatin molds and porcine eye tissue Basic Protocol 2: Creating an open-globe injury using a solenoid device Alternate Protocol 1: Constructing a computer-controlled system for open-globe injury Alternate Protocol 2: Constructing a pressure measurement system for tracking intraocular pressure Support Protocol 1: Assessing ocular compliance in porcine eyes Support Protocol 2: Assessing outflow rate from the anterior chamber Support Protocol 3: Assessing burst pressure in porcine eyes.

Probucol enhances the therapeutic efficiency of mesenchymal stem cells in the treatment of erectile dysfunction in diabetic rats by prolonging their survival time via Nrf2 pathway

BackgroundIntracavernous injection of mesenchymal stem cells (MSCs) is a promising method for diabetic mellitus-induced erectile dysfunction (DMED), but short survival time of MSCs in cavernous is a fatal defect for therapy. This study investigated therapeutic efficiency and potential mechanism of probucol combined with MSCs.MethodsIn vivo study, a total of forty-eight 10-week-old male Sprague-Dawley (SD) rats were used. Twelve rats received intraperitoneal injection of PBS as the sham group; the rest received intraperitoneal injection of 60 mg/kg streptozotocin to establish DM models. DM rats were randomly divided into three groups: received intracavernosal (IC) injection of either PBS (DM group), MSCs (M group), or administrated probucol after intracavernosal injection of MSCs (P + M group). Erectile function was assessed by electrical stimulation of the cavernous nerves with real-time intracavernous pressure measurement. After euthanasia, penile tissue was investigated for histologic examination and Western blotting. In in vitro experiment, H2O2 was used to create oxidative stress environment to detect changes in cell viability. CCK8 was used to measure cell viability of MSCs treated with or without probucol. Intracellular ROS changes were detected by flow cytometry. Autophagy and apoptosis were detected by Western blotting and confocal microscopy.ResultsRecovery of erectile function was observed in the P + M group. The combination therapy decreased fibrosis and increased endothelial function compared with MSC therapy alone. Western blotting results confirmed the increased expression of Nrf2 and HO-1 in cavernous body. H2O2 induced high oxidative stress and reduced cell viability in vitro, which was gradually reversed with increased concentration of probucol. H2O2 reduced Nrf2 expression, which was reversed by probucol’s intervention. Furthermore, the expression of Bax, Caspase3, and Cleaved-Caspase3 decreased, and the expression of Bcl-2 increased in a dose-dependent manner because of probucol’s intervention. In addition, Beclin1 and LC3II both increased in a dose-dependent manner. Meanwhile, the expression of P62 decreased. In the study of autophagy flux, we found probucol did not block it.ConclusionProbucol enhanced therapeutic efficiency of MSCs in DMED by prolonging their survival time, which mediated through improving the transplanted microenvironment of MSCs, increasing self-antioxidant ability of MSCs, strengthening protective autophagy, and inhibiting apoptosis of MSCs via Nrf2 pathway.Graphical abstractSchematic model showing combined probucol and MSCs to improve DMED. Probucol increases self-antioxidant ability of MSCs, strengthening protective autophagy and inhibiting apoptosis via Nrf2/HO-1 and Nrf2/autophagy pathways.

Metal-embedded fiber optic sensor packaging and signal demodulation scheme towards high-frequency dynamic measurements in harsh environments

Optical fiber-based sensors are commonly used for industrial monitoring and control processes due to their small size, resistance to electromagnetic interference, and ability to perform a wide variety of high-precision measurements. However, implementing optical fiber sensors in harsh environments is challenging because they are small and fragile. Proper packaging of fiber-optic sensors could extend their use to harsh environments, including at high temperature and under high radiation. Furthermore, conventional fiber optic-based measurement systems often use computationally expensive signal processing algorithms which hinder their use in high-frequency dynamic applications. This work reports on the design of an optical fiber-pressure sensor system based on low-coherence interferometry that uses a metal-embedded optical fiber to provide a robust sensor package. A novel phase demodulation scheme is proposed to extract length changes from the deformation of a thin diaphragm within a Fabry–Pérot cavity to measure pressure. The sensor has been tested to ±100kPa, has a theoretical linear response over a ±270kPa dynamic range (24dB maximum signal-to-noise ratio), and can resolve pressure transients up to 3910kPa/s. Sampling at 100kHz, the present sensor can resolve 2kPa dynamic pressures at frequencies up to 2kHz. Faster transients on the order of tens to hundreds of kHz can theoretically be resolved at the expense of decreasing the maximum resolvable amplitude. A methodology for designing a LCI pressure sensor for a given application is outlined based on the limitations imposed by the Nyquist criterion, the diaphragm's resonant frequency, the LCI optoelectronics, and the phase demodulation scheme. The sensor is the first to implement a low-coherence light source and a Fabry–Pérot interferometer designed to provide real-time high-fidelity pressure measurements using a metal-embedded optical fiber. The demonstrated sensor provides a platform for sensing in harsh conditions such as in nuclear and energy applications.

NISP: An NFC to I2C Sensing Platform With Supply Interference Reduction for Flexible RFID Sensor Applications

This paper presents a fully passive 13.56MHz Radio Frequency Identification (RFID) to I2C platform integrated circuit (IC), which has been optimized to reduce supply interference, for RFID sensor applications. In order to reduce the supply interference, this paper proposes a methodology to analyze the power supply rejection (PSR) for the power path. The PSR of the power path is effectively optimized by modifying the low-dropout regulator (LDO) topology. In order to support various highprecision I2C sensors and eliminate the micro-controller, an I2C master is integrated on-chip directly. This minimizes the complexity of the overall system. This design utilizes an internal volatile memory to exchange the communication information between RFID and I2C. Therefore the RFID and I2C communication operate independently, so that both communications can maintain maximum compatibility and flexibility. The chip is fabricated in a standard $0.35-\mu \text{m}$ CMOS technology and mounted to a tuned RFID transponder coil on an FR4 PCB substrate. Measurements show that the ripple reduction of this proposed LDO reaches 26 dB from 400 Hz to 25MHz in the worst case. During the communication, the ripple of the supply voltage V DDA reaches a maximum 44 mV, while the input ripple of the unregulated DC voltage V DCA reaches maximum 892 mV. A multi-sensor Bosch BME280 is tested with and without supply interference reduction. The result shows that the sensor’s resolution improves 6.4 times with the proposed supply interference reduction technique. The RFID to I2C platform IC was employed in a demonstrator for wireless real-time measurement of temperature, humidity, and pressure using two commercially available sensor ICs and two RFID readers.

Wireless intravesical device for real-time bladder pressure measurement: Study of consecutive voiding in awake minipigs.

Traditional urodynamics have poor correlation with urological symptoms. Ambulatory urodynamics may improve this correlation but the need for a transurethral catheter and the time-consuming nature of this examination limits its use. Therefore, the objective of this study was to develop a wireless real-time bladder pressure measurement device for repeated and prolonged-term measurement of bladder behavior in awake pigs. The Bladder Pill is an intravesical device with a pressure microsensor and a 3-dimensional inductive coupling coil for energy supply. A corresponding external coil provides wireless power transmission and real-time communication of bladder pressure data. To test the correlation between the pressure data measured by the device and by standard methods, we compared static water column pressures with this device and water-filled urodynamic catheter systems. In vivo assessment of awake voiding by the pill was done by introducing the bladder pill into the bladder of Göttingen minipigs. An air-charged urodynamic catheter was introduced transurethrally as control for pressure measurements. The optimal physical configuration of the pill was investigated to maximize the containment in the bladder. We used two versions of external signal receivers (one waistband and one rectangular frame) to test the optimal external signal capture. Next to that, we performed short-term and medium-term comparative pressure studies. The in vitro static pressure measurement demonstrated a mean difference of less than 1 cm H2O between the methods. The optimal design of the pill for maximal retainment in the bladder proved to be a pigtail configuration. The bending of the device during bladder contractions caused offset of 2.7 +/- 1.4 cm H2O (mean +/- SD) on the pressure measurements. The rectangular frame performed signal capture during 5 consecutive voids with a good correlation of the pressure measurements. The device can be inserted through the urethra and is retrieved using string or endoscopic extraction. In conclusion, wireless long-term measurement of bladder pressure is demonstrated and yields comparable results to current available catheter methods of measurement in a pig model.

Loop analysis of the anal sphincter complex in fecal incontinent patients using functional luminal imaging probe.

Cardiac loops have been used extensively to study myocardial function. With changes in cardiac pump function, loops are shifted to the right or left. Functional luminal imaging probe (FLIP) recordings allow for loop analysis of the anal sphincter and puborectalis muscle (PRM) function. The goal was to characterize anal sphincter area-pressure/tension loop changes in fecal incontinence (FI) patients. Fourteen healthy subjects and 14 patients with FI were studied. A custom-designed FLIP was placed in the vagina and then in the anal canal, and deflated in 20-ml steps, from 90 to 30 ml. At each volume, subjects performed maximal voluntary squeezes. Area-pressure (AP) and area-tension (AT) loops were generated for each squeeze cycle. Three-dimensional ultrasound imaging of the anal sphincter and PRM were obtained to determine the relationship between anal sphincter muscle damage and loop movements. With the increase in bag volume, AP loops and AT loops shifted to the right and upward in normal subjects (both anal and vaginal). The shift to the right was greater, and the upward movement was less in FI patients. The difference in the location of AP loops and AT loops was statistically significant at volumes of 50 ml to 90 ml (P < 0.05). A similar pattern was found in the vaginal loops. There is a significant relationship between the damage to the anal sphincter and PRM, and loop location of FI patients. We propose AP and AT loops as novel ways to assess the anal sphincter and PRM function. Such loops can be generated by real-time measurement of pressure and area within the anal canal.NEW & NOTEWORTHY We describe the use of area-pressure (AP) and area-tension (AT)-loop analysis of the anal sphincters and puborectalis muscles in normal subjects and fecal incontinent patients using the functional luminal imaging probe (FLIP). There are differences in the magnitude of the displacement of the loops with increase in the FLIP bag volume between normal subjects and patients with fecal incontinence. The latter group shifts more to the right in AP and AT space.

A Novel Device for Simultaneous Measurement of Nostril Air Flow Pressure and Temperature using Fiber Bragg Grating Sensor

This paper presents the design, development, calibration and demonstration of non-invasive, Nostril Pressure and Temperature Measurement Device (NPTD) employing Fiber Bragg Grating (FBG) sensors for the simultaneous, accurate and real-time measurement of nostril air flow pressure and temperature which can aid in clinical diagnosis of nasal dysfunction and associated nose disorders. The unique design of NPTD enables the comfortable measurement of randomly varying air flow pressure and temperature of both the nostrils simultaneously. To calibrate the pressure and temperature readouts of NPTD, suitable and in-house calibration techniques have been devised and adopted. The NPTD developed can provide certain critical features such as breathing pattern, rate of respiratory, individual nostril temperature/pressure, nostrils dominance pattern, body core temperature etc., which can aid clinicians in early diagnosis of breathing problems associated with heart, brain and lung malfunctioning. The developed NPTD is simple in design, practically implementable robust, EMI proof and non-electric, which are obligatory features for any clinical diagnostic tool used in a hospital environment.

Clinical Trial of a New Device for Real-Time Muscle Pressure Measurements in Patients at Risk for Acute Compartment Syndrome

Clinical Trial of a New Device for Real-Time Muscle Pressure Measurements in Patients at Risk for Acute Compartment Syndrome

Graphene-Based Sensors for Human Health Monitoring.

Since the desire for real-time human health monitoring as well as seamless human-machine interaction is increasing rapidly, plenty of research efforts have been made to investigate wearable sensors and implantable devices in recent years. As a novel 2D material, graphene has aroused a boom in the field of sensor research around the world due to its advantages in mechanical, thermal, and electrical properties. Numerous graphene-based sensors used for human health monitoring have been reported, including wearable sensors, as well as implantable devices, which can realize the real-time measurement of body temperature, heart rate, pulse oxygenation, respiration rate, blood pressure, blood glucose, electrocardiogram signal, electromyogram signal, and electroencephalograph signal, etc. Herein, as a review of the latest graphene-based sensors for health monitoring, their novel structures, sensing mechanisms, technological innovations, components for sensor systems and potential challenges will be discussed and outlined.

Biodegradable polymer material based smart stent: Wireless pressure sensor and 3D printed stent

In this paper, we present a 3D-printed biocompatible and biodegradable polymer stent with an integrated wireless pressure sensor, designed for advanced health monitoring applications. The Polycaprolactone (PCL) based polymer stent has a drug coating similar to conventional drug-eluting stents (DES) and a wireless pressure sensor that enables the real-time measurement of pressure inside the blood vessel. The wireless pressure sensor is made of poly(d-lactide) (PDLA), a biocompatible material that can be decomposed and absorbed together with the polymer stent in the body. The resonance frequency of the fabricated wireless pressure sensor (initially 148 MHz) decreases with blood pressure changes. Experimental results indicate that the sensitivity of the wireless pressure sensor (60 kHz/mmHg) shows a linear frequency shift within the pressure range of 0–220 mmHg.

Development of a Physics-Based Monitoring Algorithm Detecting CO2 Ingress Accidents in a Sodium-Cooled Fast Reactor

One of the benefits of the supercritical CO 2 Brayton cycle in Sodium-cooled Fast Reactors is an enhanced plant safety, since potential reactions of CO 2 with liquid sodium have been reported to be less stringent than a sodium-water reaction found in the Rankine cycle. However, moderate chemical interactions between CO 2 and liquid sodium make detecting CO 2 ingress accidents harder. Thus, this paper proposes a new physics-based detection algorithm by comparing the real-time pressure measurements of two identical heat exchangers for the early detection. The CO 2 ingress occurs owing to a crack at the pressure boundary wall, a certain self-recovery of structural damage does not happen over time, and an accident probabilistically starts at only one component of two. The proposed physics-based method with the probabilistic analysis was compared to the pure data-based method. Finally, the damage degradation was developed with a simplified mass and energy transfer model, and the proposed algorithm was verified with experimental data. The results show that a 99.99% detection probability can be achieved for the air ingress of 30 cc/s, which is equivalent to the 0.12 g/s CO 2 ingress, in a 70 s detection time, limiting down to 0.1% false alarms due to sensor noise.

Probucol improves erectile function via Activation of Nrf2 and coordinates the HO-1 / DDAH / PPAR-γ/ eNOS pathways in streptozotocin-induced diabetic rats

BackgroundDiabetic erectile dysfunction (DMED) is mainly attributed to oxidative stress, and Nrf2 plays an important role in cellular antioxidation and regulates NO production in the vascular endothelium. Probucol maintains endothelial function through its antioxidant activity. This study investigated the efficacy and mechanism of probucol in improving erectile function in streptozotocin-induced diabetic rats. MethodsIn our study, thirty 12-week-old Sprague-Dawley male rats were fasted for 12 h. All rats received a 1-time injection of intraperitoneal streptozotocin(60 mg/kg) or vehicle. After 72 h, STZ-treated rats (with random blood glucose concentrations consistently greater than 16.7 mmol/L) were considered diabetic. The diabetic rats were randomly assigned into 2 groups and treated with daily gavage feedings of probucol at doses of 0 and 500 mg/kg for 12 weeks. A positive control group underwent intraperitoneal injection of normal saline followed by daily gavage of saline solution. Erectile function was assessed by electrical stimulation of the cavernous nerves with real-time intracavernous pressure measurement. After euthanasia, penile tissue was investigated using immunohistochemistry, Western blot, and ELISA to assess the proteins of Nrf2/HO-1/DDAH/PPAR-γ/eNOS pathways. ResultsAfter treatment, the rats in the probucol group presented significantly improved erectile function (P < 0.05) than that of the diabetic group without probucol treatment (DM). Also, protein expression of Nrf2, DDAH, PPAR-γ, HO-1 and eNOS was significantly higher than that of the DM group (P < 0.05). CGMP concentrations and SOD concentrations of probucol-treated rats were higher than those of DM group (P < 0.05). The MDA levels and ADMA levels were significantly lower than those of DM group rats (P < 0.05). ConclusionProbucol can improve erectile function via activation of Nrf2, which coordinates the HO-1/DDAH/PPAR-γ/eNOS pathways in streptozotocin-induced diabetic rats.

Real-Time Intraocular Pressure Measurements in the Vitreous Chamber of Rabbit Eyes During Small Incision Lenticule Extraction (SMILE)

ABSTRACTPurpose: To investigate real-time intraocular pressure (IOP) during small incision lenticule extraction (SMILE) in rabbit eyes for myopia correction.Methods: During SMILE, real-time IOP was measured in the vitreous cavity of rabbit eyes with an optic fiber pressure sensor (OFPS). Two groups (n = 6 for each) underwent surgery, one group for a −2.00 diopter (D) refractive spherical correction and the other for a −6.00 D correction.Results: During surgery, the IOP increased once the glass contact attached to the cornea (Pre-suction), and peaked 83.94 mmHg (SD ± 23.87 mmHg) for the −2.00 D group and 89.17 mmHg (SD ± 22.66 mmHg) for the −6.00 D group, both average values were less than 110 mmHg when suction was initiated to fix the glass contact onto the cornea (Suction on). It then fell to 74.81 mmHg (SD ± 20.64 mmHg) and 76.94 mmHg (SD ± 27.43 mmHg), respectively, and remained stable during lenticule creation (Cutting). After suction stopped (Suction off), IOP fell steeply. During lenticule separation/extraction, the change in IOP was 32.26 mmHg (SD ± 2.91 mmHg). Notably, the average duration of elevated IOP during the surgery was 166.05 s (no longer than 3 min).Conclusions: The IOP fluctuations in the vitreous cavity using an OFPS in a rabbit model during SMILE showed that real-time IOP significantly was increased during Pre-suction, Suction on, Cutting, Suction off, and lenticule separation/extraction compared to baseline IOP, although, peaked at Suction on. Neither the degree of myopic correction nor central corneal thickness significantly affected these changes in IOP.

A vacuum-refilled tensiometer for deep monitoring of in-situ pore water pressure

Real-time measurement of soil water pressure has been recognized as an essential part of investigating water flow in unsaturated soils. Tensiometry, amongst different measuring techniques, is a common method for direct evaluation of water pressure. However, the lower limit of measurable water pressure by a conventional tensiometer becomes even more limited by increasing its length in the vertical installation. This paper describes development of a vacuum-refilled tensiometer (VRT) for monitoring soil water pressure independent of installation depth. This is achieved by fixing the distance between pressure sensor and ceramic cup together with incorporating an ancillary vacuum-refilling assembly into its design. The assembly allows for more efficient replacement of diffused air into the ceramic cup and reservoir with water. The new tensiometer is designed to withstand both negative and positive water pressure of up to almost one bar. In addition, the response time of the tensiometer to a change in negative water pressure for its working range (≥ -80 kPa) is very quick, in the order of seconds and one minute at most. The long-term performance of the new tensiometer is evaluated through a five-month monitoring program in the laboratory, simulating cyclic wetting and drying in the field.

Test of a Tube-Shaped Artificial Skin Sensor Array for Colonoscopies

Thin-film stretchable sensors are believed to have a great applications on devices with curved surfaces. As one type of these sensors, electronic skins (e-skins) for pressure measurement have the potential to provide protection to the human body by feeding back the contact pressure. One of the applications is to monitor the contact pressure from a colonoscope to the colonic wall during a colonoscopy to prevent perforation and hemorrhaging. Many studies have reported the highly flexible and stretchable nature of e-skin sensors. However, no effort has been made to investigate their performance in a colon simulator. In this paper, we developed a new technique to make ultra-thin, highly stretchable electrodes on thin films. Then we successfully built a three-layer tube-shaped tactile sensor with high conformability and stretchability. We then investigated the pressure generated by various bending curvatures on a colonoscope. Finally, we performed a real-time pressure measurement with the whole sensing system on a fake colonoscope in a colon-simulator. The measured pressure was obtained and visualized on a computer screen. These experiments validated the applicability of the designed sensor and revealed the actual stress distribution on a tube-shaped e-skin sensor array in a colon-simulator. This research could be the starting point of the effort to upgrade the strategies of colonoscopy for safer operations and could provide new routines to optimize tactile sensor design for other medical applications.

Noninvasive Real-time Measurement of Subglottal Pressure during Speech and Singing

Noninvasive Real-time Measurement of Subglottal Pressure during Speech and Singing

Analysis of a GMR-based plethysmograph transducer and its utility for real-time Blood Pressure measurement.

The paper presents study and analysis of a Giant Magneto Resistance (GMR)-based magneto plethysmograph and illustrates its efficacy as a tool for real-time cuff-less measurement of Blood Pressure (BP). The proposed scheme employs two GMR sensors and associated biasing and signal conditioning in its architecture. The delay between output of the GMR sensors is used to estimate the BP. The methodology, circuits and signal processing stages used are described in the paper. A prototype of the GMR-sensing solution is developed and tested. Initially, tests are carried out to determine the quality and characteristics of the plethysmographs produced by developed sensor unit, in different conditions such as various body positions, bias current etc. Good quality bio-signals were obtained during the above tests. Then, the experiments were conducted on 29 volunteers to find the feasibility of developed scheme as a BP monitor. The results obtained show that the performance of developed BP monitor is within acceptable limits.