Calibration and Modeling of the Semmes-Weinstein Monofilament for Diabetic Foot Management.

Diabetic foot is a serious complication that poses significant risks for diabetic patients. The resulting reduction in protective sensitivity in the plantar region requires early detection to prevent ulceration and ultimately amputation. The primary method employed for evaluating this sensitivity loss is the 10 gf Semmes-Weinstein monofilament test, commonly used as a first-line procedure. However, the lack of calibration in existing devices often introduces decision errors due to unreliable feedback. In this article, the mechanical behavior of a monofilament was analytically modeled, seeking to promote awareness of the impact of different factors on clinical decisions. Furthermore, a new device for the automation of the metrological evaluation of the monofilament is described. Specific testing methodologies, used for the proposed equipment, are also described, creating a solid base for the establishment of future calibration guidelines. The obtained results showed that the tested monofilaments had a very high error compared to the 10 gf declared by the manufacturers. To improve the precision and reliability of assessing the sensitivity loss, the frequent metrological calibration of the monofilament is crucial. The integration of automated verification, simulation capabilities, and precise measurements shows great promise for diabetic patients, reducing the likelihood of adverse outcomes.

A Novel Low-Temperature Extrusion Method for the Fused Filament Fabrication of Fluoroelastomer Compounds.

In this work, an additive manufacturing process for extruding fully compounded thermosetting elastomers based on fluorine-containing polymer compositions is reported. Additive manufacturing printers are designed with a dry ice container to precool filaments made from curable fluoroelastomer (FKM) and perfluoroelastomer (FFKM) compounds. A support tube guides the stiffened filament towards the printer nozzle. This support tube extends near the inlet to a printer nozzle. This approach allows low-modulus, uncured rubber filaments to be printed without buckling, a phenomenon common when 3D printing low-modulus elastomers via the fused deposition modeling (FDM) process. Modeling studies using thermal analyses data from a Dynamic Mechanical Analyzer (DMA) and a Differential Scanning Calorimeter (DSC) are used to calculate the Young's modulus and buckling force, which helps us to select the appropriate applied pressure and the nozzle size for printing. Using this additive manufacturing (AM) method, the successful printing of FKM and FFKM compounds is demonstrated. This process can be used for the future manufacturing of seals or other parts from fluorine-containing polymers.

An Ex Vivo Investigation of Tactile Aesthesiometer Force in Laryngopharyngeal Sensory Testing.

BACKGROUND/OBJECTIVE: Cheung-Bearelly aesthesiometers can deliver buckling-force stimuli to the laryngopharynx and objectively evaluate sensation. Ambiguity surrounds the transformation of stimuli in the laryngopharyngeal environment. This study aims to evaluate the effect of aesthesiometer size, saliva, successive compressions, and angles of tissue contact on stimulus force delivered. METHODS: An ex vivo stimulus delivery device was constructed to measure the buckling force of aesthesiometers. Dry and saliva-saturated aesthesiometers (6-0, 5-0, 4.5-0, and 4-0) were each compressed six times on cadaveric buccal mucosa on an electronic balance. The force for each compression was recorded at 0, 15, 30, 45, and 60° from the vertical plane. 240 compressions were analyzed utilizing a mixed-effects statistical model. RESULTS: The mean force delivered by the 6-0, 5-0, 4.5-0, and 4-0 aesthesiometers were 0.017, 0.082, 0.120, and 0.268 g respectively (p < 0.001). Mean force significantly reduced for the 4-0 aesthesiometer at 30° (p = 0.003) and 60° (p = 0.001). Force decreased by the 4th compression for the 5-0 aesthesiometer (p = 0.004) and after one compression for the 4.5-0 (p = 0.004) and 4-0 (p < 0.001) aesthesiometer. By the 4th compression, the 4.5-0 aesthesiometer was indistinguishable (p > 0.05) from the 5-0 aesthesiometer. The effect of saliva was insignificant (p = 0.83). CONCLUSION: Aesthesiometers can deliver discrete buckling-force stimuli to evaluate laryngopharynx sensory function. Up to 60° (15° for 4-0 aesthesiometer) deviation from orthogonal tissue contact and salivary forces do not significantly alter force delivered. 4.5-0 aesthesiometers should be exchanged after three compressions. For all other aesthesiometers, force reduction after six compressions is likely clinically insignificant given current laryngopharyngeal sensory testing protocols. LEVEL OF EVIDENCE: N/A Ex Vivo Laboratory Design Laryngoscope, 133:1933-1937, 2023.

Wearable Soft Microtube Sensors for Quantitative Home-Based Erectile Dysfunction Monitoring.

Quantifiable erectile dysfunction (ED) diagnosis involves the monitoring of rigidity and tumescence of the penile shaft during nocturnal penile tumescence (NPT). In this work, we introduce Erectile Dysfunction SENsor (EDSEN), a home-based wearable device for quantitative penile health monitoring based on stretchable microtubular sensing technology. Two types of sensors, the T- and R-sensors, are developed to effectively measure penile tumescence and rigidity, respectively. Conical models mimicking penile shaft were fabricated with polydimethylsiloxane (PDMS) material, using different base to curing agent ratios to replicate the different hardness properties of a penile shaft. A theoretical buckling force chart for the different penile models is generated to determine sufficiency criteria for sexual intercourse. An average erect penile length and circumference requires at least a Young's modulus of 179 kPa for optimal buckling force required for satisfactory sexual intercourse. The conical penile models were evaluated using EDSEN. Our results verified that the circumference of a penile shaft can be accurately measured by T-sensor and rigidity using the R-sensor. EDSEN provides a private and quantitative method to detect ED within the comfortable confines of the user's home.

Buckling Force Variability of Semmes⁻Weinstein Monofilaments in Successive Use Determined by Manual and Automated Operation.

(1) Objective: This study was conducted with the objective of characterizing the variability of a force on a simulated skin surface using the Semmes⁻Weinstein monofilament test (SWMT). (2) Research Design and Methods: Two distinct experiments were performed to determine the effects of human hand motion variability on the monofilament buckling force, and to determine the monofilament's mechanical properties using a positioning stage. (3) Results: In manual operation (by human hand motion), the buckling force over the ten compressions decreased by over 10%, and the human hand motion variations during the SWMT may have impacted the buckling force. When the SWMT was performed under manual control, the buckling force was closely correlated with the number of compressions. In automated operation (by positioning stage), the buckling force was affected not only by the number of compressions but also by both the velocity and the contact angle between the monofilament and the skin surface. (4) Conclusions: The buckling force decreased in ten successive compressions, independent of the hand motion. Hence, medical staff need to consider not only the operator's hand motion but also the effect of repeated trials.