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18 pages, 7110 KiB

Open AccessArticle

Visual Feedback Control of a Rat Ankle Angle Using a Wirelessly Powered Two-Channel Neurostimulator

by Masaru Takeuchi, Keita Watanabe, Kanta Ishihara, Taichi Miyamoto, Katsuhiro Tokutake, Sota Saeki, Tadayoshi Aoyama, Yasuhisa Hasegawa, Shigeru Kurimoto and Hitoshi Hirata

Sensors 2020, 20(8), 2210; https://doi.org/10.3390/s20082210 - 14 Apr 2020

Cited by 5 | Viewed by 3662

Abstract

Peripheral nerve disconnections cause severe muscle atrophy and consequently, paralysis of limbs. Reinnervation of denervated muscle by transplanting motor neurons and applying Functional Electrical Stimulation (FES) onto peripheral nerves is an important procedure for preventing irreversible degeneration of muscle tissues. After the reinnervation [...] Read more.

Peripheral nerve disconnections cause severe muscle atrophy and consequently, paralysis of limbs. Reinnervation of denervated muscle by transplanting motor neurons and applying Functional Electrical Stimulation (FES) onto peripheral nerves is an important procedure for preventing irreversible degeneration of muscle tissues. After the reinnervation of denervated muscles, multiple peripheral nerves should be stimulated independently to control joint motion and reconstruct functional movements of limbs by the FES. In this study, a wirelessly powered two-channel neurostimulator was developed with the purpose of applying selective FES to two peripheral nerves—the peroneal nerve and the tibial nerve in a rat. The neurostimulator was designed in such a way that power could be supplied wirelessly, from a transmitter coil to a receiver coil. The receiver coil was connected, in turn, to the peroneal and tibial nerves in the rat. The receiver circuit had a low pass filter to allow detection of the frequency of the transmitter signal. The stimulation of the nerves was switched according to the frequency of the transmitter signal. Dorsal/plantar flexion of the rat ankle joint was selectively induced by the developed neurostimulator. The rat ankle joint angle was controlled by changing the stimulation electrode and the stimulation current, based on the Proportional Integral (PI) control method using a visual feedback control system. This study was aimed at controlling the leg motion by stimulating the peripheral nerves using the neurostimulator. Full article

(This article belongs to the Special Issue Micro/Nanosensors for Cellular/Tissue Measurement)

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13 pages, 35888 KiB

Open AccessArticle

Head-Mounted Display-Based Microscopic Imaging System with Customizable Field Size and Viewpoint

by Tadayoshi Aoyama, Sarau Takeno, Masaru Takeuchi and Yasuhisa Hasegawa

Sensors 2020, 20(7), 1967; https://doi.org/10.3390/s20071967 - 1 Apr 2020

Cited by 7 | Viewed by 2516

Abstract

In recent years, the use of microinjections has increased in life science and biotechnology fields; specific examples include artificial insemination and gene manipulation. Microinjections are mainly performed based on visual information; thus, the operator needs high-level skill because of the narrowness of the [...] Read more.

In recent years, the use of microinjections has increased in life science and biotechnology fields; specific examples include artificial insemination and gene manipulation. Microinjections are mainly performed based on visual information; thus, the operator needs high-level skill because of the narrowness of the visual field. Additionally, microinjections are performed as the operator views a microscopic image on a display; the position of the display requires the operator to maintain an awkward posture throughout the procedure. In this study, we developed a microscopic image display apparatus for microinjections based on a view-expansive microscope. The prototype of the view-expansive microscope has problems related to the variations in brightness and focal blur that accompany changes in the optical path length and amount of reflected light. Therefore, we propose the use of a variable-focus device to expand the visual field and thus circumvent the above-mentioned problems. We evaluated the observable area of the system using this variable-focus device. We confirmed that the observable area is 261.4 and 13.9 times larger than that of a normal microscope and conventional view-expansive microscopic system, respectively. Finally, observations of mouse embryos were carried out by using the developed system. We confirmed that the microscopic images can be displayed on a head-mounted display in real time with the desired point and field sizes. Full article

(This article belongs to the Special Issue Micro/Nanosensors for Cellular/Tissue Measurement)

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9 pages, 2045 KiB

Open AccessArticle

Optimization of Experimental Variables Influencing Apoptosome Biosensor in HEK293T Cells

by Azarakhsh Oladzad, Maryam Nikkhah and Saman Hosseinkhani

Sensors 2020, 20(6), 1782; https://doi.org/10.3390/s20061782 - 23 Mar 2020

Cited by 8 | Viewed by 3014

Abstract

The apoptotic protease-activating factor 1 (Apaf-1) split luciferase biosensor has been used as a biological tool for the detection of early stage of apoptosis. The effect of doxorubicin in a cell-based assay and the addition of cytochrome c and ATP in a cell-free [...] Read more.

The apoptotic protease-activating factor 1 (Apaf-1) split luciferase biosensor has been used as a biological tool for the detection of early stage of apoptosis. The effect of doxorubicin in a cell-based assay and the addition of cytochrome c and ATP in a cell-free system have been used to test the functionality of the reporter for the detection of apoptosome formation. Here, our data established a drug- and cytochrome c/ATP-independent way of apoptosis induction relying on the expression of the biosensor itself to induce formation of apoptosome. Overexpression of Apaf-1 constructs led to increased split luciferase activity and caspase-3 activity in the absence of any drug treatment. Caspase-3 activity was significantly inhibited when caspase-9DN was co-overexpressed, while the activity of the Apaf1 biosensor was significantly increased. Our results show that the Apaf-1 biosensor does not detect etoposide-induced apoptosis. Full article

(This article belongs to the Special Issue Micro/Nanosensors for Cellular/Tissue Measurement)

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