Concentration of white blood cells from whole blood by dual centrifugo-pneumatic siphoning with density gradient medium

Due to the pervasiveness of HIV infections in developing countries there exists a need for a low-cost, user-friendly point-of-care device which can be used to monitor the concentration of T-lymphocytes in the patient’s blood expressing the CD4+ epitope. As a first step towards developing a microfluidic “lab-on-a-disc” platform with this aim we present the concentration of white blood cells from whole blood using a density medium in conjunction with centrifugo-pneumatic siphon valves [1]. Two such valves are actuated simultaneously, removing the bulk of plasma through the upper valve and the bulk of WBCs through the lower valve while leaving the vast majority of red blood cells in the centrifugal chamber

Auto-actuated sequential relelase valves for lab-on-a-disc systems

In microfluidic biomedical systems valving is often of critical importance for process control. In centrifugal microfluidics valves are typically actuated through changing the centrifugal force seen by the working liquid. Here we present for the first time a new valving structure (based on dissolvable films) where the entry of liquid into a chamber on the disc can trigger the release of liquid from a chamber located elsewhere on the disc. These valves can be configured such that multiple valves can be released in a sequential manner independent of external inputs

Special Issue on “Advances in Microfluidics Technology for Diagnostics and Detection”

In recent years microfluidics and lab-on-a-chip havecome to the forefront in diagnostics and detection [...

Fast kVp-Switching Dual Energy CT for PET Attenuation Correction

X-ray CT images are used routinely for attenuation correction in PET/CT systems. However, conventional CT-based attenuation correction (CTAC) can be inaccurate in regions containing iodine contrast agent. Dual-energy (DE) CT has the potential to improve the accuracy of attenuation correction in PET, but conventional DECT can suffer from motion artifacts. Recent X-ray CT systems can collect DE sinograms by rapidly switching the X-ray tube voltage between two levels for alternate projection views, reducing motion artifacts. The goal of this work is to study statistical methods for image reconstruction from both fast kVp-switching DE scans and from conventional dual-rotate DE scans in the context of CTAC for PET.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/86003/1/Fessler244.pd

Laboratory unit operations on centrifugal lab-on-a-disc cartridges using dissolvable-film enabled flow control

The suitability of the centrifugal “lab-on-a-disc” (LoaD) platform for point-of-use / point-of-care deployment, where ruggedness, portability, rapid turn-around times and ease-of-use are key, has resulted in increased interest from the academic community over the last decade. Recently, a new, so-called event-triggered valving paradigm was introduced which circumvented a number of the limitations of commonly used, rotationally actuated valves and complex instrument-controlled valving. In the dissolvable-film based event-triggered approach, it is the liquid movement about a disc which actuates a valve; thus enabling the concatenating of a number of liquid handling operations into an automated cascade. Functioning broadly independent of spin rate, the number of discrete valving operations is only limited by the available disc real-estate. In this work we present this valving paradigm to control a network of discrete Laboratory Unit Operations (LUOs) which, with experienced design, can be integrated together to implement complex fluidic assays. We describe how these valves can be configured, using Boolean-like network relationships, to implement LUOs such as sequential washing steps. We also describe how these valves can be configured to enable metering, mixing and selective routing of liquid flows. Finally, we describe how these valves can be configured to provide accurate temporal control of LUOs; thus providing an entire suite of process control technology which can be used to enable many bio-assays

Quantitative Attenuation Correction for PET/CT Using Iterative Reconstruction of Low-Dose Dual-Energy CT

We present the results of using iterative reconstruction of dual-energy CT (DECT) to perform accurate CT-based attenuation correction (CTAC) for PET emission images. Current methods, such as bilinear scaling, introduce quantitative errors in the PET emission image for bone, metallic implants, and contrast agents. DECT has had limited use in the past for quantitative CT imaging due to increased patient dose and high noise levels in the decoupled CT basis-material images. Reconstruction methods that model the acquisition physics impose a significant computational burden due to the large image matrix size (typically 512 × 512). For CTAC, however, three factors make DECT feasible: (1) a smaller matrix is needed for the transmission image, which reduces the noise per pixel, (2) a smaller matrix significantly accelerates an iterative CT reconstruction algorithm, (3) the monoenergetic transmission image at 511 keV is the sum of the two decoupled basis-material images. Initial results using a 128 × 128 matrix size for a test object comprised of air, soft tissue, dense bone, and a mixture of tissue and bone demonstrate a significant reduction of bias using DECT (from 20% to ?0% for the tissue/bone mixture). FBP reconstructed images, however, have significant noise. Noise levels are reduced from ?8% to ?3% by the use of PWLS reconstruction.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/85861/1/Fessler203.pd

A Four-Year, Seven-State Reforestation Trial with Eastern Hemlocks (\u3cem\u3eTsuga canadensis\u3c/em\u3e) Resistant to Hemlock Woolly Adelgid (\u3cem\u3eAdelges tsugae\u3c/em\u3e)

We conducted over a decade of research into individual eastern hemlock (Tsuga canadensis; hemlock) trees that are potentially resistant to hemlock woolly adelgid (Adelges tsugae; HWA), an invasive xylem-feeding insect that is capable of rapidly killing even mature trees. Following clonal propagation of these individuals, in 2015 we planted size- and age-matched HWA-resistant and HWA-susceptible hemlocks in HWA-infested forest plots in seven states. In 2019, we re-surveyed the plots; 96% of HWA-resistant hemlocks survived compared to 48% of susceptible trees. The surviving HWA-resistant trees were also taller, produced more lateral growth, retained more foliage, and supported lower densities of the elongate hemlock scale Fiorinia externa, another invasive hemlock pest, than the surviving HWA-susceptible trees. Our results suggest that HWA management may benefit from additional research exploring the identification, characterization, and use of HWA-resistant eastern hemlocks in future reforestation efforts

ICNMM2008-62014 Microchannel Fluorescent Melting Curve Analysis

ABSTRACT I

Biosensing on the centrifugal microfluidic lab-on-a-Disc platform

Lab-on-a-Disc (LoaD) biosensors are increasingly a promising solution for many biosensing applications. In the search for a perfect match between point-of-care (PoC) microfluidic devices and biosensors, the LoaD platform has the potential to be reliable, sensitive, low-cost, and easy-to-use. The present global pandemic draws attention to the importance of rapid sample-to-answer PoC devices for minimising manual intervention and sample manipulation, thus increasing the safety of the health professional while minimising the chances of sample contamination. A biosensor is defined by its ability to measure an analyte by converting a biological binding event to tangible analytical data. With evolving manufacturing processes for both LoaDs and biosensors, it is becoming more feasible to embed biosensors within the platform and/or to pair the microfluidic cartridges with low-cost detection systems. This review considers the basics of the centrifugal microfluidics and describes recent developments in common biosensing methods and novel technologies for fluidic control and automation. Finally, an overview of current devices on the market is provided. This review will guide scientists who want to initiate research in LoaD PoC devices as well as providing valuable reference material to researchers active in the field