Representing Fine Texture of Pencil Hardness by High-Frequency Vibrotactile Equivalence Conversion Using Ultra-Thin PZT-MEMS Vibrators.

This study aims to represent fine texture differences in pencil hardness using intensity segment modulation (ISM), a sensory equivalent conversion method of vibration from high to low frequencies. This method enables the presentation of delicate tactile sensations even with small transducers. We integrated this approach in the world's thinnest ultra-thin PZT-MEMS vibrator with a stylus-type device. The vibration waveforms of four types of pencil hardness were captured under the same conditions, and the differences in the frequency components were confirmed. We compared the fine texture feelings under raw signal, ISM, and ISM below 1 kHz conditions by conducting discrimination tests and subjective similarity evaluations. The results showed that ISM could reproduce similar feelings of the pencil hardness.

Lever Mechanism for Diaphragm-Type Vibrators to Enhance Vibrotactile Intensity.

Thin and light vibrators that leverage the inverse piezoelectric effect with a diaphragm mechanism are promising vibrotactile actuators owing to their form factors and high temporal and frequency response. However, generating perceptually sufficient displacement in the low-frequency domain is challenging. This study presents a lever mechanism mounted on a diaphragm vibrator to enhance the vibrotactile intensity of low-frequency vibrotactile stimuli. The lever mechanism is inspired by the tactile contact lens consisting of an array of cylinders held against the skin on a sheet that enhances micro-bump tactile detection. We built an experimental apparatus including our previously developed thin-film diaphragm-type vibrator, which reproduced the common characteristic of piezoelectric vibrators: near-threshold displacement (10 to 20 µm) at low frequency. Experiments demonstrated enhanced vibrotactile intensity at frequencies less than 100 Hz with the lever mechanism. Although the arrangement and material of the mechanism can be improved, our findings can help improve the expressiveness of diaphragm-type vibrators.

Development of wearable multi-lead ECG measurement device using cubic flocked electrode.

This paper describes the fabrication and fundamental evaluation of the cubic flocked electrode (CFE), which is a dry electrode that is fabricated using electrostatic flocking technology. The development of a wearable multi-lead electrocardiogram (ECG) measurement device using the CFE is also reported. To enable the measurement of ECG signals with sufficient quality for medical applications, the occurrence of motion artifacts (MAs) is the most important problem to be overcome. Therefore, it is necessary to stabilize the contact between the patient's skin and the dry electrode. Because the CFE developed in this work offers both contact stability and flexibility, it is expected to enable ECG measurements with low MA levels. In this study, it is demonstrated that the number of MAs caused by respiration can be reduced when the CFE contact is made at a contact pressure of approximately 500 Pa using MA evaluation equipment that was developed in-house. Additionally, a wearable multi-lead ECG is designed and fabricated based on this contact pressure (500 Pa). The results of the demonstration experiment show that the ECG measurements are successful to the same extent as a conventional medical device.

Microneedle Array-Assisted, Direct Delivery of Genome-Editing Proteins Into Plant Tissue.

Genome editing in plants employing recombinant DNA often results in the incorporation of foreign DNA into the host genome. The direct delivery of genome-editing proteins into plant tissues is desired to prevent undesirable genetic alterations. However, in most currently available methods, the point of entry of the genome-editing proteins cannot be controlled and time-consuming processes are required to select the successfully transferred samples. To overcome these limitations, we considered a novel microneedle array (MNA)-based delivery system, in which the needles are horizontally aligned from the substrate surface, giving it a comb-like configuration. We aimed to deliver genome-editing proteins directly into the inner layers of leaf tissues; palisade, the spongy and subepidermal L2 layers of the shoot apical meristem (SAM) which include cells that can differentiate into germlines. The array with needles 2 µm wide and 60 µm long was effective in inserting into Arabidopsis thaliana leaves and Glycine max (L.) Merr. (soybeans) SAM without the needles buckling or breaking. The setup was initially tested for the delivery of Cre recombinase into the leaves of the reporter plant A. thaliana by quantifying the GUS (ß-glucuronidase) expression that occurred by the recombination of the loxP sites. We observed GUS expression at every insertion. Additionally, direct delivery of Cas9 ribonucleoprotein (RNP) targeting the PDS11/18 gene in soybean SAM showed an 11 bp deletion in the Cas9 RNP target site. Therefore, this method effectively delivered genome-editing proteins into plant tissues with precise control over the point of entry.

Practical Evaluation of Printed Strain Sensors Based on Long-Term Static Strain Measurements.

Recent progress in printable electronics has enabled the fabrication of printed strain sensors for diverse applications. These include the monitoring of civil infrastructure, the gradual aging of which raises concerns about its effective maintenance and safety. Therefore, there is a need for automated sensing systems that provide information on the performance and behavior of engineering structures that are subjected to dynamic and static loads. The application of printed strain sensors in structural health monitoring is of growing interest owing to its large-area and cost-effective fabrication process. Previous studies have proven the suitability of printable strain sensors for dynamic strain measurements on bridges; however, the analysis of the long-term stability of printed sensors during static strain measurements is still lacking. Thus, this study aims to assess the long-term stability of printed strain sensor arrays and their suitability for the static strain analysis of large civil structures. The developed sensors and a dedicated wireless data acquisition system were deployed inside a gravity dam, which was selected as the field test environment. This test environment was chosen owing to the relatively stable temperature inside the dam and the very slow static strain changes associated with periodic water level changes. The results exhibited an average signal drift of 20 µÏµ over 127 days. One of the sensor arrays was installed on a small crack in the dam structure; it showed that the sensors can track static strain changes owing to variations in the crack opening, which are related to the water level changes in the dam. Overall, the results of the developed sensors exhibit good strain sensitivity and low signal drift. This indicates the potential suitability of printed sensors for applications in the static strain analysis of engineering structures.

Real-time, non-invasive thrombus detection in an extracorporeal circuit using micro-optical thrombus sensors.

INTRODUCTION: Real-time, non-invasive monitoring of thrombus formation in extracorporeal circuits has yet to be achieved. To address the challenges of conventional optical thrombus detection methods requiring large devices that limit detection capacity, we developed a micro-optical thrombus sensor. METHODS: The proposed micro-optical thrombus sensor can detect the intensity of light scattered by blood at wavelengths of 660 and 855 nm. Two thrombus sensors were installed on in vitro circuit: one at the rotary blood pump and one at a flow channel. To evaluate the variation in the ratio of incident light intensity at each wavelength of the two sensors, Rfluct (for 660 nm) and Ifluct (for 855 nm) were defined. Using fresh porcine blood as a working fluid, we performed in vitro tests of haematocrit (Hct) and oxygen saturation (SaO2) variation and thrombus detection. Thrombus tests were terminated after Rfluct or Ifluct showed a larger change than the maximum range of those in the Hct and SaO2 variation test. RESULTS: In all three thrombus detection tests, Ifluct showed a larger change than the maximum range of those in the Hct and SaO2 variation test. After the tests, thrombus formation was confirmed in the pump, and there was no thrombus in the flow channel. The results indicate that Ifluct is an effective parameter for identifying the presence of a thrombus. CONCLUSION: Thrombus detection in an extracorporeal circuit using the developed micro-optical sensors was successfully demonstrated in an in vitro test.

Relationship between Contact Pressure and Motion Artifacts in ECG Measurement with Electrostatic Flocked Electrodes Fabricated on Textile.

To develop a wearable multi-lead electrocardiogram (ECG) measuring system, we fabricated the electrodes and wires by using electrostatic flocking technology on a textile. By using this technology, it was possible to fabricate many electrodes and wires, simultaneously. Also the flocked electrodes and wires had stretchability and washing resistance properties. To use dry electrodes, it is important to reduce the influence of motion artifacts (MAs). The results of the experiment with the skin phantom revealed that the contact pressure between the skin and the electrode is an important factor in MA reduction. Then, we conducted experiments with a human body to determine the relationship between the contact pressure and the MAs. Under the pressures of 200 Pa and 500 Pa, MAs were observed. Meanwhile, under the pressures of 1000 Pa, 2000Pa and 4000 Pa, the ECG signals under rest and deep breathing conditions were able to be measured without MAs. Considering the comfortability, the contact pressure from 1000 Pa to 2000 is preferable. Finally, we fabricated the wearable ECG measuring system and succeeded in measuring 18-lead ECG signals. The measured ECG waveform is in good agreement with the ECG waveform measured by a commercial system.

Regeneration of granular activated carbon with adsorbed trichloroethylene using wet peroxide oxidation.

The objective of this study is to clarify the regeneration of granular activated carbon (GAC) adsorbed trichloroethylene (TCE) using wet peroxide oxidation (WPO). TCE and TOC concentrations decreased during WPO, whereas Cl(-) accumulated in water indicating that TCE was not only decomposed but was also mineralized to Cl(-) and CO(2) using WPO. Regeneration efficiencies (q/q(0)) of GAC regenerated at 150, 165 and 180 degrees C (initial pH 4) were 0.36, 0.45, 0.48, respectively. In addition, regeneration efficiencies of GAC regenerated in the solution of various initial pH (2.5, 3.0, 4.0) at 180 degrees C were 0.71, 0.60, 0.48, respectively. These results suggest that regeneration of GAC is more effective at higher reaction temperature and lower initial pH of the solution. In the repeated regeneration of GAC, the adsorption capacity of GAC for TCE gradually decreased and regeneration efficiency of the regenerated GAC at sixth step was 0.40. The adsorption capacity loss of regenerated GAC is probably due to oxidation of GAC during WPO.

Degradation of chemical substances using wet peroxide oxidation under mild conditions.

The objectives of this study are to clarify the degradation mechanism of chemical substances using wet peroxide oxidation (WPO) under mild condition (150 degrees C) and to confirm the removal of polychlorinated biphenyls (PCBs) in soil using this oxidation process. Acetic and oxalic acids were mineralized using WPO. TOC removal rate of acetic acid was highest in the solution of pH 2.5. However, TOC removal rate was decreased with the increase in pH and TOC were hardly removed in the solution of pH 7 and 10. The decomposition rate of isobutyric acid by WPO decreased in the presence of radical scavenger (t-BuOH). The results suggested that the decomposition of chemical substances using WPO proceeded by hydroxyl radical (OH radical). PCBs in soil were also decomposed by performing WPO at 150 degrees C.