Locomotion response of airborne, ambulatory and aquatic insects to thermal stimulation using piezoceramic microheaters

This paper reports the locomotion response of airborne, ambulatory and aquatic insects to thermal stimulation. A finite element model has been developed to predict the variation of insect–stimulator interface temperature with input power. Piezothermal stimulators have been fabricated from lead zirconate titanate (PZT) using a batch mode micro ultrasonic machining process. Typical sizes range from 200 µm to 3.2 mm. For PZT stimulators, the temperature and thermal efficiency reach the maximum value around the resonance frequency which is typically in the range of 650 kHz to 47 MHz. Experiments have been conducted on green June beetles (GJBs), Madagascar hissing roaches and green diving beetles (GDBs) in order to show the versatility of the proposed technique. The stimulators have been implanted near the antennae of the GJBs and on either side of the thorax of the Madagascar hissing roaches and GDBs, respectively. In all cases, the insects move away from the direction of the actuated stimulator. The left and right turns are statistically similar. Thermal stimulation achieves an overall success rate of 78.7%, 92.8% and 61.6% in GJBs, roaches and GDBs, respectively. On average, thermal stimulation results in an angle turn of about 13.7°–16.2° on GJBs, 30°–45° on the roaches and 30°–50° on GDBs. The corresponding average input power is 360, 330 and 100 mW for GJBs, roach and GDBs, respectively. Scaling limits of the PZT stimulators for operating these stimulators are also discussed.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/90797/1/0960-1317_21_12_125002.pd

A non-contact method for spatially localized sedimentation of particles from liquid suspensions using Marangoni forces

This paper presents the directed sedimentation of suspension particles in a thin layer of liquid (≤1 mm) onto a featureless glass substrate by Marangoni flows. A programmable 16 _ 8 array of surface mount resistors suspended 0.1–2 mm above the liquid provides dynamic millimeter-sized heat sources to locally heat the liquid surface to temperatures from approximately 28.5 to 36.5 °C. The heaters in this array can be activated independently by a graphical user interface, creating surface tension gradients along the liquid surface. The resulting Marangoni flows direct spatially localized particle sedimentation on the substrate. The resultant sedimentation patterns and accumulation levels depend on factors such as the temperature gradient at the liquid surface, number of active heaters and type of liquid used. For example, when a single heater is activated, a liquid surface temperature elevation of 6.9 °C results in a localized sedimentation of suspended weed pollen Kochia scoparia (_ = 25 µm) in silicone oil DC-704 over a region of 2.9 mm 2 that is centered directly beneath the active heater. This sedimentation method is a contactless technique, which reduces the likelihood of sample contamination.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/90796/1/0960-1317_21_11_115028.pd

Joining of Ceramics and Ceramic Matrix Composites (CMC) for Aerospace and Energy Applications

SiC-based ceramics and composites (SiC, C/SiC & SiC/SiC) are more and more extensively used as advanced materials for aerospace and energy applications. Existing applications are expanding continuously and require advanced materials, design and joining technologies. The objective of this thesis was to join SiC-based ceramic matrix composites (CMC), ceramics (SiC, Mullite, Alumina) and SiC-based ceramic foams for aerospace and energy applications. The research was aimed to develop strong, oxidation resistant and high temperature stable joints. A novel joining technique defined “RM-Wrap” (RM=Mo, Nb, Ta, W Refractory Metals) has been developed within this thesis. The developed technique is a novel brazing technology named RM-Wrap after the metal used as a wrap to contain one or more silicon foils (e.g. Mo-Wrap when a Mo wrap is used to contain a Si foil). It is a pressure-less joining technology performed at 1450 oC, under an inert environment (Argon flow). Joining materials are in-situ formed composites made of refractory metals silicides (MoSi2, NbSi2, TaSi2 and WSi2) embedded in a silicon matrix. RM-Wrap is a highly tailorable joining technique: the quantity of each phase can be modified and more than one refractory metals can be used together. RM-Wrap has been very effective in joining both coated and uncoated CMC, porous and non-porous materials: ceramics (oxide and non-oxide), CMC (SiC-based) and highly porous substrates (SiC foams) having porosity higher than 80% have been soundly joined. vii The joint morphology (interphase and interface) and elemental composition of the joining material was investigated in detail using FESEM and EDS which showed uniform, continuous and crack free joints. XRD investigation confirms the formation of metal silicides. Oxidation resistance of joints was carried out at 1100 oC for 30 minutes (for CMC joints) and 6 hours (for monolithic ceramic joints) in the air; prior and post oxidation examination of joint morphology showed no morphological change and joints remained firmly joined. Sandwich structures have been developed by Mo-wrap joining two C/SiC as “skins” to the “core” SiC foam. Sandwich structures were tested for thermal shock resistance from RT to 1100 oC in the air for 2 minutes. Three cycles on a single sandwich structure were performed, which remained joined and the joining material composition unchanged. Joints were mechanically tested in three different modes (i) compression, (ii) tensile and (iii) torsion. Joint strength was higher than the interlaminar shear strength of composites as the fracture was always observed in composites. In case of monolithic ceramic (SiC) a mixed failure (cohesive and adhesive) was found, which suggest that the joint strength is comparable to ceramic one. Micro- and nanoindentation tests were also carried out on joining materials

Microheaters based on ultrasonic actuation of piezoceramic elements

This paper describes the use of micromachined lead zirconate titanate (PZT) piezoceramic elements for heat generation by ultrasonic energy dissipated within the elements and surrounding media. Simulations based on three-dimensional finite-element models suggest that circular disk-shaped elements provide superior steady-state temperature rise for a given cross-sectional area, volume of the PZT element and drive voltage. Experimental validation is performed using PZT-5A heaters of 3.2 mm diameter and 0.191 mm thickness. Single-element heaters and dual-element stacks are evaluated. Although the steady-state temperature generated by these heaters reaches the maximum value at the frequency of maximum electromechanical conductance, the heating effectiveness is maximized at the frequency of maximum electromechanical impedance. Stacked PZT heaters provide 3.5 times the temperature rise and 3 times greater heating effectiveness than single elements. Furthermore, the heaters attain the maximum heating effectiveness when bonded to highly damping and non-conducting substrates. A maximum temperature of 120 °C is achieved at 160 mW input power. Experiments are performed using porcine tissue samples to show the feasibility of using PZT heaters in tissue cauterization. A PZT heater probe brands a porcine tissue in 2–3 s with 10 V RMS drive voltage. The interface temperature is ≈150 °C.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/90803/1/0960-1317_21_8_085030.pd

Porous ceramics for multistage Knudsen micropumps—modeling approach and experimental evaluation

This paper describes the evaluation of four types of porous ceramics for use as thermal transpiration materials in Knudsen pumps that operate at atmospheric pressure. Knudsen pumps are motionless gas pumps that utilize thermal transpiration along a channel or a set of channels; the channels must have a temperature gradient and must constrain the flow to remain within the free molecular or transitional flow regimes. Of the ceramics evaluated, a clay-based, 15 bar synthetic ceramic (15PC) presents the most favorable properties for Knudsen pumps. For an input power of 3.4 W, a 25 _ 25 mm 2 nine-stage Knudsen pump that uses this material provides a maximum pressure head of 12 kPa and a maximum gas flow rate of ≈3.7 µL min _1 . Reliability tests demonstrate more than 11 750 h of continuous operation without any deterioration in their gas pumping capabilities. A fitted model suggests that the temporal evolution of pressure at the sealed outlet of a Knudsen pump can be captured adequately using four parameters. These parameters correspond to various nonidealities that play dominant roles in the transient response of these pumps.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/90805/1/0960-1317_21_9_095029.pd

Tailored magnetoelastic sensor geometry for advanced functionality in wireless biliary stent monitoring systems

This paper presents three types of wireless magnetoelastic resonant sensors with specific functionalities for monitoring sludge accumulation within biliary stents. The first design uses a geometry with a repeated cell shape that provides two well-separated resonant mode shapes and associated frequencies to permit spatial localization of mass loading. The second design implements a pattern with specific variation in feature densities to improve sensitivity to mass loading. The third design uses narrow ribbons joined by flexible couplers; this design adopts the advantages in flexibility and expandability of the other designs while maintaining the robust longitudinal mode shapes of a ribbon-shaped sensor. The sensors are batch patterned using photochemical machining from 25 µm thick 2605SA1 Metglas™, an amorphous Fe–Si alloy. Accumulation of biliary sludge is simulated with paraffin or gelatin, and the effects of viscous bile are simulated with a range of silicone fluids. Results from the first design show that the location of mass loads can be resolved within ~5 mm along the length of the sensor. The second design offers twice the sensitivity to mass loads (3000–36 000 ppm mg−1) of other designs. The third design provides a wide range of loading (sensitive to at least 10× the mass of the sensor) and survives compression into a 2 mm diameter tube as would be required for catheter-based delivery.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/85405/1/jmm10_7_075040.pd

A microfabricated steel and glass radiation detector with inherent wireless signaling

This paper describes an investigation of the performance compromises imposed by a manufacturing approach that utilizes lithographic micromachining processes to fabricate a wireless beta/gamma radiation detector. The device uses in-package assembly of stainless steel electrodes and glass spacers. These elements are micromachined using photochemical etching and powder blasting, respectively. The detector utilizes a commercial, TO-5 package that is hermetically sealed at 760 Torr with an Ar fill-gas. Gas microdischarges between the electrodes, which are initiated by the radiation, transmit wideband wireless signals. The detector diameter and height are 9 and 9.6 mm, respectively, and it weighs 0.97 g. The device performance has been characterized using various sealed, radioisotope sources, e.g., 30–99 µCi from 137 Cs (which is a beta and gamma emitter) and 0.1 µCi from 90 Sr (which is a pure beta emitter). It has a measured output of >15.5 counts s _1 when in close proximity to 99 µCi from 137 Cs. The wireless signaling spans 1.25 GHz at receiving antenna-to-detector distances >89 cm, when in close proximity to a 0.1 µCi 90 Sr source. The estimated intrinsic detection efficiency (i.e. with the background rate subtracted) is 3.34% as measured with the biasing arrangement described in the paper.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/90792/1/0960-1317_21_1_015003.pd

Survey on Fault Tolerance Startgies for Advance Microelectronics Chip

In the complex advance microelectronics based system, handling units are managing gadgets of littler size, which are delicate to the transient faults. A framework should be fabricated that will perceive the presence of faults and fuses strategies to will endure these faults without troublesome the typical activity A transient fault happens in a circuit caused by the electromagnetic commotions, astronomical beams, crosstalk and power supply clamor. It is extremely hard to recognize these faults amid disconnected testing. Subsequently a region effective fault tolerant full adder for testing and fixing of transient and changeless faults happened in single and multi-net is proposed. Furthermore, the proposed design can likewise identify and fix perpetual faults. This structure acquires much lower equipment overheads with respect to the conventional equipment design. In this paper, talk about various fault tolerant methodology for CMOS and ICs

Inpatient Use of Computer-Guided Insulin Devices Moving into the Non–Intensive Care Unit Setting

Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/140357/1/dia.2015.0213.pd

High-resolution scanning thermal probe with servocontrolled interface circuit for microcalorimetry and other applications

This article presents a scanning thermal microscopy sensing system equipped with a customized micromachined thermal imaging probe and closed loop interface circuit. The micromachined thermal probe has a thin film metal bolometer sandwiched between two layers of polyimide for high thermal isolation and mechanical flexibility, and a tip with a diameter of approximately 50 nm which provides fine spatial resolution. The circuit includes a proportional-integral (PI) controller which couples to a Wheatstone bridge circuit in which the bolometer forms one leg. The PI controller adjusts power supplied to thermal probe, compensating change in heat loss from probe tip to sample and keeping the resistance bridge balanced. It permits precise control of probe temperature to within 2.3 mK, and widens its applications to microcalorimetry. The probe is used in thermal mapping and microcalorimetry applications. A calibration method based on microcalorimetric measurements of melting temperature is presented for the probe. Scanning thermal images show a high signal-to-noise ratio of 15.7 for 300 nm thick photoresist in which the minimum detectable thermal conductance change is <23 pW/K<23pW/K (which corresponds to a topographic change of 7.2 nm). Subsurface scans show a signal-to-noise ratio of 15.5 for variation of 1.0% in thermal resistance for a topographically smooth surface.© 2004 American Institute of Physics.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/69814/2/RSINAK-75-5-1222-1.pd