Design and fabrication of a single membrane push-pull SPDT RF MEMS switch operated by electromagnetic actuation and electrostatic hold

In this paper, we report a new push-pull-type SPDT (single pole double throw) switch actuated by the combination of electromagnetic and electrostatic forces for low power and low voltage operation. The switch is initially actuated by large electromagnetic force to change its state and is held to maintain its state by applying electrostatic force to reduce static power consumption. The electromagnetic force can be easily generated at low voltage. The maximum actuation voltage is below 4.3 V and the required energy is 15.4 µJ per switching. It achieves signal isolation of −54 dB and insertion loss of −0.16 dB at 2 GHz, respectively. For 20 GHz operation, isolation and insertion loss were measured as −36 dB and −0.52 dB, respectively. The proposed SPDT switch combines two switching elements in a single structure, simplifying the overall structure and control signals and eliminating mismatches between the two switching elements. The dimension of the switch has been optimized using FEM simulation and analytical calculations. We have successfully carried out a lifetime test over more than 166 million cycles with the maximum actuation voltage below 4.3 V.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/85424/1/jmm10_3_035028.pd

A low-voltage three-axis electromagnetically actuated micromirror for fine alignment among optical devices

In this paper, a new three-axis electromagnetically actuated micromirror structure has been proposed and fabricated. It is electromagnetically actuated at low voltage using an external magnetic field. The main purpose of this work was to obtain a three-axis actuated micromirror in a mechanically robust structure with large static angular and vertical displacement at low actuation voltage for fine alignment among optical components in an active alignment module as well as conventional optical systems. The mirror plate and torsion bars are made of bulk silicon using a SOI wafer, and the actuation coils are made of electroplated Au. The maximum static deflection angles were measured as +/-4.2 for x -axis actuation and +/-.2 for y -axis actuation, respectively. The maximum static vertical displacement was measured as +/-42 um for z -axis actuation. The actuation voltages were below 3 V for all actuation. The simulated resonant frequencies are several kHz, and these imply that the fabricated micromirror can be operated in sub-millisecond order. The measured radius of curvature (ROC) of the fabricated micromirror is 7.72 cm, and the surface roughness of the reflector is below 1.29 nm which ensure high optical performance such as high directionality and reflectivity. The fabricated micromirror has demonstrated large actuated displacement at low actuation voltage, and it enables us to compensate a larger misalignment value when it is used in an active alignment module. The robust torsion bar and lifting bar structure formed by bulk silicon allowed the proposed micromirror to have greater operating stability. The additional degree of freedom with z -axis actuation can decrease the difficulty in the assembly of optical components and increase the coupling efficiency between optical components.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/65102/2/jmm9_8_085007.pd

Akt1-Inhibitor of DNA binding2 is essential for growth cone formation and axon growth and promotes central nervous system axon regeneration.

Mechanistic studies of axon growth during development are beneficial to the search for neuron-intrinsic regulators of axon regeneration. Here, we discovered that, in the developing neuron from rat, Akt signaling regulates axon growth and growth cone formation through phosphorylation of serine 14 (S14) on Inhibitor of DNA binding 2 (Id2). This enhances Id2 protein stability by means of escape from proteasomal degradation, and steers its localization to the growth cone, where Id2 interacts with radixin that is critical for growth cone formation. Knockdown of Id2, or abrogation of Id2 phosphorylation at S14, greatly impairs axon growth and the architecture of growth cone. Intriguingly, reinstatement of Akt/Id2 signaling after injury in mouse hippocampal slices redeemed growth promoting ability, leading to obvious axon regeneration. Our results suggest that Akt/Id2 signaling is a key module for growth cone formation and axon growth, and its augmentation plays a potential role in CNS axonal regeneration

Venous Hemangioma of Parapharyngeal Space with Calcification

A hemangioma of the parapharyngeal space (PPS) is an extremely rare tumor and is responsible for 0.5-1% of all tumors occurring in the PPS. We report a case of PPS venous hemangioma in a 49-year-old woman presenting with diffuse swelling in the submandibular region. A preoperative computed tomography (CT) scan showed a cystic mass with multiple calcifications in the PPS. The calcific nodules were round and about 2 mm in diameter. The hemangioma was completely resected via a transcervical approach. During surgery, we found several calcific nodules, which represented phleoboliths or areas of thrombosis with dystrophic calcification. Despite its rarity, a venous hemangioma of the PPS should be considered in a differential diagnosis when a cystic mass with calcification is found by CT scan. To our knowledge, this is the first reported case of a PPS venous hemangioma; we describe its pathognomonic findings on imaging

A low-voltage Two-axis Electromagnetically Actuated Micromirror with Bulk Silicon Mirror

ABSTRACT In this paper, a new micromirror structure has been proposed and fabricated. The proposed micromirror is electromagnetically actuated along two-axis at low voltage using an external magnetic field. The mirror plates and torsion bars are made of bulk silicon and the actuation coils are made of electroplated copper. The maximum deflection angles have been measured as ±4.35° for x-axis actuation and ±15.7° for y-axis actuation. The actuation voltages are below 4.2V for xaxis actuation and 1.76V for y-axis actuation, respectively

Engineered lentivector targeting of dendritic cells for in vivo immunization

We report a method of inducing antigen production in dendritic cells by in vivo targeting with lentiviral vectors that specifically bind to the dendritic cell–surface protein DC-SIGN. To target dendritic cells, we enveloped the lentivector with a viral glycoprotein from Sindbis virus engineered to be DC-SIGN–specific. In vitro, this lentivector specifically transduced dendritic cells and induced dendritic cell maturation. A high frequency (up to 12%) of ovalbumin (OVA)-specific CD8+ T cells and a significant antibody response were observed 2 weeks after injection of a targeted lentiviral vector encoding an OVA transgene into naive mice. This approach also protected against the growth of OVA-expressing E.G7 tumors and induced regression of established tumors. Thus, lentiviral vectors targeting dendritic cells provide a simple method of producing effective immunity and may provide an alternative route for immunization with protein antigens

A Multimodal Neural Activity Readout Integrated Circuit for Recording Fluorescence and Electrical Signals

Monitoring the electrical neural signals is an important method for understanding the neuronal mechanism. In particular, in order to perform a cell-type-specific study, it is necessary to observe the concentration of calcium ions using fluorescent indicators in addition to measuring the electrical neural signal. This paper presents a multimodal multichannel neural activity readout integrated circuit that can perform not only electrical neural recording but also fluorescence recording of neural activity for the cell-type-specific study of heterogeneous neuronal cell populations. For monitoring the calcium ions, the photodiode generates the current according to the fluorescence expressed by the reaction between the genetically encoded calcium indicators and calcium ions. The time-based fluorescence recording circuit then records the photodiode current. The electrical neural signal captured by the microelectrode is recorded through the low-noise amplifier, variable gain amplifier, and analog-to-digital converter. The proposed integrated circuit is fabricated in a 1-poly 6-metal (1P6M) 0.18- ??m CMOS process. The fluorescence recording circuit achieves a recording range of 81 dB (75 pA to 860 nA) and consumes a power of 724 nW/channel. The electrical recording circuit achieves an input-referred noise of 2.7 ??Vrms over the bandwidth of 10 kHz, while consuming the power of 4.9 ??W /channel. The functionality of the proposed circuits is verified through the in vivo and in vitro experiments. Compared to the conventional neuroscience tools, which consist of bulky off-chip components, this neural interface is implemented in a compact size to perform multimodal neural recording while consuming low power