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

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

Real-time measurement of the three-axis contact force distribution using a flexible capacitive polymer tactile sensor

In this paper, we report real-time measurement results of various contact forces exerted on a new flexible capacitive three-axis tactile sensor array based on polydimethylsiloxane (PDMS). A unit sensor consists of two thick PDMS layers with embedded copper electrodes, a spacer layer, an insulation layer and a bump layer. There are four capacitors in a unit sensor to decompose a contact force into its normal and shear components. They are separated by a wall-type spacer to improve the mechanical response time. Four capacitors are arranged in a square form. The whole sensor is an 8 _ 8 array of unit sensors and each unit sensor responds to forces in all three axes. Measurement results show that the full-scale range of detectable force is around 0–20 mN (250 kPa) for all three axes. The estimated sensitivities of a unit sensor with the current setup are 1.3, 1.2 and 1.2%/mN for the x- , y- and z -axes, respectively. A simple mechanical model has been established to calculate each axial force component from the measured capacitance value. Normal and shear force distribution images are captured from the fabricated sensor using a real-time measurement system. The mechanical response time of a unit sensor has been estimated to be less than 160 ms. The flexibility of the sensor has also been demonstrated by operating the sensor on a curved surface of 4 mm radius of curvature.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/90798/1/0960-1317_21_3_035010.pd

Scalable Multiplexed Drugâ Combination Screening Platforms Using 3D Microtumor Model for Precision Medicine

Cancer heterogeneity is a notorious hallmark of this disease, and it is desirable to tailor effective treatments for each individual patient. Drug combinations have been widely accepted in cancer treatment for better therapeutic efficacy as compared to a single compound. However, experimental complexity and cost grow exponentially with more target compounds under investigation. The primary challenge remains to efficiently perform a largeâ scale drug combination screening using a small number of patient primary samples for testing. Here, a scalable, easyâ toâ use, highâ throughput drug combination screening scheme is reported, which has the potential of screening all possible pairwise drug combinations for arbitrary number of drugs with multiple logarithmic mixing ratios. A â Christmas tree mixerâ structure is introduced to generate a logarithmic concentration mixing ratio between drug pairs, providing a large drug concentration range for screening. A threeâ layer structure design and special inlets arrangement facilitate simple drug loading process. As a proof of concept, an 8â drug combination chip is implemented, which is capable of screening 172 different treatment conditions over 1032 3D cancer spheroids on a single chip. Using both cancer cell lines and patientâ derived cancer cells, effective drug combination screening is demonstrated for precision medicine.Combination drug treatment has been widely accepted for better cancer therapeutic efficacy, yet the discovery of combinations is hindered by experimental complexity. A combinatorial drug screening platform is developed, covering all pairwise combinations of 8 drugs with multiple mixing ratios in a linear/logarithmic scale. It facilitates the discovery of synergistic drug combinations by allowing over 1000 experiments per chip at once.Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/146315/1/smll201703617.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/146315/2/smll201703617-sup-0001-S1.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/146315/3/smll201703617_am.pd

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

Real-time label-free quantitative monitoring of biomolecules without surface binding by floating-gate complementary metal-oxide semiconductor sensor array integrated with readout circuitry

We report a label-free field-effect sensing array integrated with complementary metal-oxide semiconductor (CMOS) readout circuitry to detect the surface potential determined by the negative charge in DNA molecules. For real-time DNA quantification, we have demonstrated the measurements of DNA molecules without immobilizing them on the sensing surface which is composed of an array of floating-gate CMOS transistors. This nonimmobilizing technique allows the continuous monitoring of the amount of charged molecules by injecting DNA solutions sequentially. We have carried out the real-time quantitative measurement of 19 bp oligonucleotides and analyzed its sensitivity as a function of pH in buffer solutions. (c) 2007 American Institute of Physics.open2

Ultracompliant Carbon Nanotube Direct Bladder Device

The bladder, stomach, intestines, heart, and lungs all move dynamically to achieve their purpose. A long‐term implantable device that can attach onto an organ, sense its movement, and deliver current to modify the organ function would be useful in many therapeutic applications. The bladder, for example, can suffer from incomplete contractions that result in urinary retention with patients requiring catheterization. Those affected may benefit from a combination of a strain sensor and electrical stimulator to better control bladder emptying. The materials and design of such a device made from thin layer carbon nanotube (CNT) and Ecoflex 00–50 are described and demonstrate its function with in vivo feline bladders. During bench‐top characterization, the resistive and capacitive sensors exhibit stability throughout 5000 stretching cycles under physiology conditions. In vivo measurements with piezoresistive devices show a high correlation between sensor resistance and volume. Stimulation driven from platinum‐silicone composite electrodes successfully induce bladder contraction. A method for reliable connection and packaging of medical grade wire to the CNT device is also presented. This work is an important step toward the translation of low‐durometer elastomers, stretchable CNT percolation, and platinum‐silicone composite, which are ideal for large‐strain bioelectric applications to sense or modulate dynamic organ states.An ultracompliant strain sensor and stimulation electrode array is described built from carbon nanotube, low‐durometer silicone, and a PDMS/Pt‐microparticle composite. This work provides an early demonstration of stretchable electronics to address the condition of underactive bladder by real‐time volume detection and evoked contractions with particular attention to fabrication and strain sensor performance in physiologic conditions.Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/152012/1/adhm201900477-sup-0001-S1.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/152012/2/adhm201900477.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/152012/3/adhm201900477_am.pd

Carbon-Nanotube Optoacoustic Lens for Focused Ultrasound Generation and High-Precision Targeted Therapy

We demonstrate a new optical approach to generate high-frequency (>15 MHz) and high-amplitude focused ultrasound, which can be used for non-invasive ultrasound therapy. A nano-composite film of carbon nanotubes (CNTs) and elastomeric polymer is formed on concave lenses, and used as an efficient optoacoustic source due to the high optical absorption of the CNTs and rapid heat transfer to the polymer upon excitation by pulsed laser irradiation. The CNT-coated lenses can generate unprecedented optoacoustic pressures of >50 MPa in peak positive on a tight focal spot of 75 μm in lateral and 400 μm in axial widths. This pressure amplitude is remarkably high in this frequency regime, producing pronounced shock effects and non-thermal pulsed cavitation at the focal zone. We demonstrate that the optoacoustic lens can be used for micro-scale ultrasonic fragmentation of solid materials and a single-cell surgery in terms of removing the cells from substrates and neighboring cells

EGFL6 regulates the asymmetric division, maintenance and metastasis of ALDH+ ovarian cancer cells

Little is known about the factors that regulate the asymmetric division of cancer stem-like cells. Here we demonstrate that EGFL6, a stem cell regulatory factor expressed in ovarian tumor cells and vasculature, regulates ALDH+ ovarian cancer stem-like cells (CSC). EGFL6 signaled at least in part via the oncoprotein SHP2 with concomitant activation of ERK. EGFL6 signaling promoted the migration and asymmetric division of ALDH+ ovarian CSC. As such, EGFL6 increased not only tumor growth but also metastasis. Silencing of EGFL6 or SHP2 limited numbers of ALDH+ cells and reduced tumor growth, supporting a critical role for EGFL6/SHP2 in ALDH+ cell maintenance. Notably, systemic administration of an EGFL6-neutralizing antibody we generated restricted tumor growth and metastasis, specifically blocking ovarian cancer cell recruitment to the ovary. Together, our results offer a preclinical proof of concept for EGFL6 as a novel therapeutic target for the treatment of ovarian cancer