Piezoresistive effect has been a dominant mechanical sensing principle that has been widely employed in a range of sensing applications. This transducing concept still receives great attentions because of the...
The integration of micro- and nanoelectronics into or onto biomedical devices can facilitate advanced diagnostics and treatments of digestive disorders, cardiovascular diseases, and cancers. Recent developments in gastrointestinal endoscopy and balloon catheter technologies introduce promising paths for minimally invasive surgeries to treat these diseases. However, current therapeutic endoscopy systems fail to meet requirements in multifunctionality, biocompatibility, and safety, particularly when integrated with bioelectronic devices. Here, we report materials, device designs, and assembly schemes for transparent and stable cubic silicon carbide (3C-SiC)-based bioelectronic systems that facilitate tissue ablation, with the capability for integration onto the tips of endoscopes. The excellent optical transparency of SiC-on-glass (SoG) allows for direct observation of areas of interest, with superior electronic functionalities that enable multiple biological sensing and stimulation capabilities to assist in electrical-based ablation procedures. Experimental studies on phantom, vegetable, and animal tissues demonstrated relatively short treatment times and low electric field required for effective lesion removal using our SoG bioelectronic system. In vivo experiments on an animal model were conducted to explore the versatility of SoG electrodes for peripheral nerve stimulation, showing an exciting possibility for the therapy of neural disorders through electrical excitation. The multifunctional features of SoG integrated devices indicate their high potential for minimally invasive, cost-effective, and outcome-enhanced surgical tools, across a wide range of biomedical applications.
This paper presents the development of a dual-axis gas gyroscope, whose working principle is based on the convective heat transfer and thermoresistive effect of lightly doped silicon. The working principle and the cross-sensitivity of the gas gyroscope are also analyzed. Experiments were performed to confirm the simulation results and good agreement has been achieved. The measured sensitivities for the X-axis and Y-axis were 0.107 mV deg−1 s−1 and 0.102 mV deg−1 s−1, respectively. Compared with a gyroscope of the same configuration but using tungsten as a sensing element, this gyroscope has 42 times greater sensitivity and one quarter the power consumption. These advantageous characteristics are inherited from the high TCR and high resistance of lightly doped p-type silicon. Nonlinearity and cross-sensitivity were measured to be smaller than 0.07% FS and 0.5% FS, respectively. The effect of acceleration on the sensitivity is 0.02 (deg s−1)/g and the measurement resolution based on sensitivity and noise analyses is 0.05 deg s−1. The relations between sensor performance, power consumption and ambient temperature were also realized.
A novel air-flow generator based on the effect of ion wind has been developed by the simultaneous generation of both positive and negative ions using two electrodes of opposite polarity placed in parallel. Unlike the conventional unipolar-generators, this bipolar configuration creates an ion wind, which moves away from both electrodes and yields a very low net charge on the device. The electro-hydrodynamic behaviour of air-flow has been experimentally and numerically studied. The velocity of ion wind reaches values up to 1.25 m/s using low discharge current 5 μA with the kinetic conversion efficiency of 0.65% and the released net charge of -30 fA, 8 orders of magnitude smaller compared with the discharge current. Due to easy scalability and low net charge, the present configuration is beneficial to applications with space constraints and/or where neutralized discharge process is required, such as inertial fluidic units, circulatory flow heat transfer, electrospun polymer nanofiber to overcome the intrinsically instability of the process, or the formation of low charged aerosol.
With the aim of designing a mechanical drug delivery system involving a bio-actuator, we fabricated a Micro Electro Mechanical Systems (MEMS) device that can be driven through contraction of skeletal muscle cells. The device is composed of a Si-MEMS with springs and ratchets, UV-crosslinked collagen film for cell attachment, and C2C12 muscle cells. The Si-MEMS device is 600 μm x 1000 μm in size and the width of the collagen film is 250 ~ 350 μm, which may allow the device to go through small blood vessels. To position the collagen film on the MEMS device, a thermo-sensitive polymer was used as the sacrifice-layer which was selectively removed with O₂ plasma at the positions where the collagen film was glued. The C2C12 myoblasts were seeded on the collagen film, where they proliferated and formed myotubes after induction of differentiation. When C2C12 myotubes were stimulated with electric pulses, contraction of the collagen film-C2C12 myotube complex was observed. When the edge of the Si-MEMS device was observed, displacement of ~8 μm was observed, demonstrating the possibility of locomotive movement when the device is placed on a track of adequate width. Here, we propose that the C2C12-collagen film complex is a new generation actuator for MEMS devices that utilize glucose as fuel, which will be useful in environments in which glucose is abundant such as inside a blood vessel.
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