Development of an NO2 Gas Sensor Based on Laser-Induced Graphene Operating at Room Temperature.

A novel, in situ, low-cost and facile method has been developed to fabricate flexible NO2 sensors capable of operating at ambient temperature, addressing the urgent need for monitoring this toxic gas. This technique involves the synthesis of highly porous structures, as well as the specific development of laser-induced graphene (LIG) and its heterostructures with SnO2, all through laser scribing. The morphology, phases, and compositions of the sensors were analyzed using scanning electron microscopy, X-ray diffraction, X-ray photoelectron spectroscopy and Raman spectroscopy. The effects of SnO2 addition on structural and sensor properties were investigated. Gas-sensing measurements were conducted at room temperature with NO2 concentrations ranging from 50 to 10 ppm. LIG and LIG/SnO2 sensors exhibited distinct trends in response to NO2, and the gas-sensing mechanism was elucidated. Overall, this study demonstrates the feasibility of utilizing LIG and LIG/SnO2 heterostructures in gas-sensing applications at ambient temperatures, underscoring their broad potential across diverse fields.

A novel micro drill design based on Ros-DrillⒸ.

This paper presents the development of a novel micro drill device for single living organisms. Currently, microinjection for mice and some other species is performed with the help of piezo-driven actuators with a very small amount of mercury column in the proximal end of the pipette in order to increase the success rate. However, the toxicity of mercury exhibits a risk factor both for the operator and the injected cells. Therefore, mercury-free devices have become a necessity. Here, a novel micro drill is developed based on the same principle of Ros-DrillⒸ piercing approach; piercing via rotational movements. The new drill is driven by a brushless motor, and it incorporates the micropipette holder. Both the amplitude and the frequency of rotational oscillations can be adjusted in very wide ranges. The experiments reveal that the drill is suitable for different tasks such as microinjection and biopsy of different organisms. It presents good performance in terms of success rate, ease of usage, compactness and compatibility with different manipulation systems.

Geometric characterization of cell membrane of mouse oocytes for ICSI.

Intracytoplasmic sperm injection (ICSI) is a broadly utilized assisted reproductive technology. A number of technologies for this procedure have evolved lately, such as the most commonly utilized piezo-assisted ICSI technique (P-ICSI). An important problem with this technique, however, is that it requires a small amount of mercury to stabilize the tip of the penetration micropipette. A completely different and mercury-free injection technology, called the rotationally oscillating drill (Ros-Drill) (RD-ICSI), was recently developed. It uses microprocessor-controlled rotational oscillations of a spiked micropipette after the pipette deforms the membrane to a certain tension level. Inappropriate selection of this initiation instant typically results in cell damage, which ultimately leads to unsuccessful ICSI. During earlier manual clinical tests of Ros-Drill, the technicians' expertise determined this instant in an ad hoc fashion. In this paper, we introduce a computer-vision-based tool to mechanize this process with the objective of maintaining the repeatability and introducing potential automation. Computer images are used for monitoring the membrane deformations and curvature variations as the basis for decision making. The main contribution of this paper is in the specifics of the computer logic to perform the monitoring. These new tools are expected to provide a practicable means for automating the Ros-Drill-assisted ICSI operation.

Rotationally oscillating drill (Ros-Drill) for mouse ICSI without using mercury.

Intracytoplasmic sperm injection (ICSI) is an important assisted reproductive technology (ART). Due to deployment difficulties and low efficiency of the earlier (conventional) version of ICSI, especially in the mouse, a piezo-assisted ICSI technique had evolved as a popular ART methodology in recent years. An important and remaining problem with this technique, however, is that it requires small amounts of mercury to stabilize the pipette tip when piezoelectric force pulses are applied. To eliminate this problem we developed and tested a completely different and mercury-free technology, called the "Ros-Drill" (rotationally oscillating drill). The technique uses microprocessor-controlled rotational oscillations on a spiked micropipette without mercury or piezo. Preliminary experimental results show that this new microinjection technology gives high survival rate (>70% of the injected oocytes) and fertilization rate (>80% of the survived oocytes), and blastocyst formation rates in early trials (approximately 50% of the survived oocytes). Blastocysts created by Ros-Drill ICSI were transferred into the uteruses of pseudopregnant surrogate mothers and healthy pups were born and weaned. The Ros-Drill ICSI technique is automated and therefore; it requires a very short preliminary training for the specialists, as evidenced in many successful biological trials. These advantages of Ros-Drill ICSI over conventional and piezo-assisted ICSI are clearly demonstrated and it appears to have resolved an important problem in reproductive biology.

New optical sensor for monitoring the micropipette motion.

A novel noncontact sensor is developed to monitor the displacements of a drawn glass pipette tip. These pipettes are commonly used in various cellular-injection applications, from in vitro fertilization to cloning. The physics of the underlying cellular-piercing process, however, is quite complex and presently not fully understood primarily due to the absence of appropriate motion sensors. A high-sensitivity noncontact sensor is needed to study this delicate microdynamics. We report here on an optical microdevice, which is developed for this objective. In the core of the sensing, properly positioned four photodiodes receive the light, which emanates from the target micropipette. Appropriate electronics and sensitivity-enhancement techniques are also utilized. The experimental results are presented from a preliminary test study on a prototype setup. These results are very encouraging in that we can already report submicrometer-level motion-detection capability.

New technology for cellular piercing: rotationally oscillating mu-injector, description and validation tests.

ICSI (intracytoplasmic sperm injection) procedure is one of the most commonly used cellular-injection processes. In ICSI a drawn glass pipette is pushed against the biological cell and a series of force impulses are exerted on it axially to achieve the piercing through the zona and the membrane in sequence for the ensuing injection. In most advanced applications a piezo actuator creates this impulsive forcing. This procedure presently requires a very small mercury column inside the glass pipette which is found to be helpful especially for minimizing the transverse oscillations. Despite the toxic mercury, the procedure is commonly utilized in many laboratories. Earlier investigations point out that considerable lateral tip oscillations of the injection pipette remain as the piezo-electric pulses are introduced. Such oscillations damage the cell membrane and impart adverse effects on the success rate of the injection. In this study, we introduce a novel microinjection procedure, which will remedy the shortfalls of the present technology. The highlight of this procedure is the introduction of rotational oscillations to the pipette during the drilling. These oscillations of small amplitudes (few degrees) and high enough frequencies (100 Hz and higher) are shown to create very effective piercing. The so-called Ros-Drill is a mercury-free and minimally invasive device of which the prototypes are designed and built including the relevant peripheral control hardware and software. Preliminary experimental results are presented on mouse oocytes and they are very encouraging. In the early trials on mouse oocytes, several blastocyst stage developments are reported using new drilling device. We also explain in this text the implementation protocols developed for the new technology.