Fabrication of high aspect ratio, non-line-of-sight vias in silicon carbide by a two-photon absorption method.

The future of Moore's Law for high-performance integrated circuits (ICs) is going to be driven more by advanced packaging and three-dimensional (3D) integration than by simply decreasing transistor size. 3D ICs offer low-power consumption, high-performance and a smaller footprint compared to conventional 2D ICs. The key enabling technology to 3D integration is the interposer that provides interconnects to route signals between the chiplets that comprise the IC. However, the fabrication of high-aspect ratio through wafer vias (TWVs), that provide electrical and mechanical connection between chiplets on the top and bottom of the interposer, is one of the important challenges that limit interposer performance. Current fabrication technologies are limited by tapering effects and the need for direct line of sight to the fabrication surface. These limit the possible aspect ratios of vias and require large, complicated surface traces to connect the vias to the chiplets. Here, we demonstrate the fabrication of high-aspect ratio, non-line-of-sight TWVs in silicon carbide (SiC). SiC provides better mechanical, chemical, and thermal performance than silicon (Si). The technique uses an electro-chemical etch process that utilizes two-photon absorption to create any arbitrary 3D structure in SiC allowing for direct, subsurface routing between chiplets.

A Rapid Response Electrochemical Biosensor for Detecting Thc In Saliva.

Marijuana is listed as a Schedule I substance under the American Controlled Substances Act of 1970. As more U.S. states and countries beyond the U.S. seek legalization, demands grow for identifying individuals driving under the influence (DUI) of marijuana. Currently no roadside DUI test exists for determining marijuana impairment, thus the merit lies in detecting the primary and the most sought psychoactive compound tetrahydrocannabinol (THC) in marijuana. Salivary THC levels are correlated to blood THC levels making it a non-invasive medium for rapid THC testing. Affinity biosensing is leveraged for THC biomarker detection through the chemical reaction between target THC and THC specific antibody to a measure signal output related to the concentration of the targeted biomarker. Here, we propose a novel, rapid, electrochemical biosensor for the detection of THC in saliva as a marijuana roadside DUI test with a lower detection limit of 100 pg/ml and a dynamic range of 100 pg/ml - 100 ng/ml in human saliva. The developed biosensor is the first of its kind to utilize affinity-based detection through impedimetric measurements with a rapid detection time of less than a minute. Fourier transform infrared spectroscopy analysis confirmed the successful immobilization of the THC immobilization assay on the biosensing platform. Zeta potential studies provided information regarding the stability and the electrochemical behavior of THC immunoassay in varying salivary pH buffers. We have demonstrated stable, dose dependent biosensing in varying salivary pH's. A binary classification system demonstrating a high general performance (AUC = 0.95) was employed to predict the presence of THC in human saliva. The biosensor on integration with low-power electronics and a portable saliva swab serves as a roadside DUI hand-held platform for rapid identification of THC in saliva samples obtained from human subjects.

Ultrasensitive and Rapid-Response Sensor for the Electrochemical Detection of Antibiotic Residues within Meat Samples.

Antimicrobial use in livestock has emerged as a pressing global issue because of the rise of antimicrobial-resistant bacteria. Regulatory authorities across the globe have taken steps to discourage the misuse of these antibiotics by banning or limiting the use of medically important antibiotics in food animals. However, to ensure that food animals are not being administered antibiotics inappropriately, there is a need for a reliable, raid-response biosensor that can detect the presence of these antibiotic residuals in meat products. We have developed an affinity-based electrochemical biosensor for the label-free detection of ceftiofur residues in meat samples. The sensor uses a self-assembled immunoassay to target the ceftiofur biomarker by employing electrochemical impedance spectroscopy to probe the interfacial capacitive changes as ceftiofur binds to the sensor surface. We have demonstrated a platform that can detect ceftiofur within 15 min of introducing the sample at concentrations down to 0.01 ng/mL in 1× phosphate-buffered saline and 10 ng/mL in 220 mg ground turkey meat samples.

The lateral preoptic area and ventral pallidum embolden behavior.

While recently completing a study of the effects of stimulating the lateral preoptic area (LPO) and ventral pallidum (VP) on locomotion and other movements, we also noticed LPO and VP effects on motivational drive and threat tolerance. Here, we have investigated these latter effects by testing conditioned place preference (CPP), behavior on the elevated plus maze (EPM) and the willingness of sated rats to occupy a harshly lit open field center to acquire sweet pellets, a measure of threat tolerance, following infusions of vehicle or bicuculline (bic) into the LPO and VP. LPO-bic infusions robustly increased total locomotion, and, in direct proportion, occupancy of both the harshly lit field center and open arms of the EPM. LPO bic also generated CPP, but did not increase sweet pellet ingestion. These effects were attenuated by dopamine D1 and D2 receptor antagonists, whether given individually or as a cocktail and systemically or infused bilaterally into the nucleus accumbens. VP-bic infusions did not increase total locomotion, but preferentially increased field center occupancy. VP-bic-infused rats compulsively ingested sweet pellets and did so even under the spotlight, whereas harsh illumination suppressed pellet ingestion in the control groups. VP bic produced CPP and increased open arm occupancy on the EPM. These effects were attenuated by pretreatment with dopamine receptor antagonists given systemically or as bilateral infusions into the VP, except for % distance in the field center (by D1 or D2 antagonists) and pellet ingestion (by D1 antagonist). Thus, boldness generated in association with LPO activation is tightly tied to locomotor activation and, as is locomotion itself, strongly DA dependent, whereas that accompanying stimulation of the VP is independent of locomotor activation and, at least in part, DA signaling. Furthermore, respective emboldened behaviors elicited from neither LPO nor VP could clearly be attributed to goal pursuit. Rather, emboldening of behavior seems more to be a fixed action response not fundamentally different than previously for reported locomotion, pivoting, backing, gnawing, and eating elicited by basal forebrain stimulation.

The Anatomy of a Nonfaradaic Electrochemical Biosensor.

Point-of-care (POC) testing has revolutionized diagnostic healthcare, bringing medical results directly and immediately to the patient. With faster diagnostics, more immediate clinical management decisions can be made. POC tests most often use a dipstick or swab format to detect the presence of a pathogen, disease, or other relevant biomarker. In these formats, the POC tests eliminate the need for complex lab equipment and trained personnel to collect, process, and analyze sample data for simple diagnostics. However, these tests cannot satisfy all clinical needs, because accurate quantitative results are needed. The present study serves as a template for designing a nonfaradaic electrochemical biosensor toward quantitative POC diagnostics. We focus on investigating the most important parameters when constructing a nonfaradaic biosensor through both mathematical modeling and electrochemical measurements. Furthermore, we demonstrate quantitative affinity biosensing of a model protein toward developing a POC device.

Lateral preoptic and ventral pallidal roles in locomotion and other movements.

The lateral preoptic area (LPO) and ventral pallidum (VP) are structurally and functionally distinct territories in the subcommissural basal forebrain. It was recently shown that unilateral infusion of the GABAA receptor antagonist, bicuculline, into the LPO strongly invigorates exploratory locomotion, whereas bicuculline infused unilaterally into the VP has a negligible locomotor effect, but when infused bilaterally, produces vigorous, abnormal pivoting and gnawing movements and compulsive ingestion. This study was done to further characterize these responses. We observed that bilateral LPO infusions of bicuculline activate exploratory locomotion only slightly more potently than unilateral infusions and that unilateral and bilateral LPO injections of the GABAA receptor agonist muscimol potently suppress basal locomotion, but only modestly inhibit locomotion invigorated by amphetamine. In contrast, unilateral infusions of muscimol into the VP affect basal and amphetamine-elicited locomotion negligibly, but bilateral VP muscimol infusions profoundly suppress both. Locomotor activation elicited from the LPO by bicuculline was inhibited modestly and profoundly by blockade of dopamine D2 and D1 receptors, respectively, but was not entirely abolished even under combined blockade of dopamine D1 and D2 receptors. That is, infusing the LPO with bic caused instances of near normal, even if sporadic, invigoration of locomotion in the presence of saturating dopamine receptor blockade, indicating that LPO can stimulate locomotion in the absence of dopamine signaling. Pivoting following bilateral VP bicuculline infusions was unaffected by dopamine D2 receptor blockade, but was completely suppressed by D1 receptor blockade. The present results are discussed in a context of neuroanatomical and functional organization underlying exploratory locomotion and adaptive movements.