University of Michigan

Hyeun Joong Yoon

Sunitha Nagrath

Max S Wicha

Diane M Simeone

Lianette Rivera Baez

Eric Lin

Jinsang Kim

Robert T Kennedy

Vasudha Murlidhar

Apoorv Shanker

Woong Hee Lee

Thitaphat Ngernsutivorakul

Microdialysis sampling is an essential tool for in vivo neuro-chemical monitoring. Conventional dialysis probes are over 220 &#x3bc;m in diameter and have limited flexibility in design because they are made by assembly using preformed membranes. The probe size constrains spatial resolution and governs the amount of tissue damaged caused by probe insertion. To overcome these limitations, we have developed a method to microfabricate probes in Si that are 45 &#x3bc;m thick 180 &#x3bc;m wide. The probes contain a buried, U-shaped channel that is 30 &#x3bc;m deep 60 &#x3bc;m wide and terminates in ports for external connection. A 4 mm length of the probe is covered with a 5 &#x3bc;m thick nanoporous membrane. The membrane was microfabricated by deep reactive ion etching through a porous aluminum oxide layer. The microfabricated probe has cross-sectional area that is 79% less than that of the smallest conventional microdialysis probes. The probes yield 2-7% relative recovery at 100 nL/min perfusion rate for a variety of small molecules. The probe was successfully tested in vivo by sampling from the striatum of live rats. Fractions were collected at 20 min intervals (2 &#x3bc;L) before and after an injection of 5 mg/kg, i.p amphetamine. Analysis of fractions by liquid chromatography-mass spectrometry revealed reliable detection of 13 neurochemicals, including dopamine and acetylcholine, at basal conditions. Amphetamine evoked a 43-fold rise in dopamine, a result nearly identical to a conventional dialysis probe in the same animal. The microfabricated probes have potential for sampling with higher spatial resolution and less tissue disruption than conventional probes. It may also be possible to add functionality to the probes by integrating other components, such as electrodes, optics, and additional channels.

Microfabrication of a microdialysis probe with nanoporous membrane

This disclosure provides a system for detecting rare cells. The system includes a substrate, an extension coupled to the substrate and extending outwardly from the substrate, and a functionalized graphene oxide disposed on the extension. This disclosure also provides a method for detecting rare cells using the system of this disclosure. The method includes the steps of providing the system and introducing a sample of bodily fluid to the system such that the sample interacts with the functionalized graphene oxide.

Functionalized graphene oxide system for detecting rare cells

A microfluidic device for detecting rare cells in a fluid sample comprises the rare cell and other cells. The microfluidic device comprises an inlet for receiving the fluid sample, a labyrinth channel structure in fluid communication with the inlet, and an outlet in fluid communication with the labyrinth channel structure for collecting the rare cells separated from the other cells in the fluid sample. The labyrinth channel structure comprises at least one channel through which the fluid sample flows. The at least one channel has a plurality of segments and a plurality of corners with each corner defined between adjacent segments. The presence of the plurality of corners induces separation of the rare cells from the other cells in the fluid sample as the rare cells move to a first equilibrium position within the at least one channel when a ratio of inertial lift forces (F) and Dean flow (F) of the fluid sample is from 2 to 10.

Microfluidic device and method for detecting rare cells

A system for detecting rare cells in a fluid is disclosed. The system includes a substrate and a mixture disposed on the substrate and including a carrier and a thermo-responsive polymer for capture and release of the rare cells. Also disclosed is a method for detecting rare cells in a fluid using a system including a substrate and a mixture that is disposed on the substrate. The mixture includes a carrier and a thermo-responsive polymer. The method includes providing the system and introducing a sample of fluid containing the rare cells into the system such that the sample interacts with the carrier for capturing the rare cells.

System for detecting rare cells

Growing community of inventors

Ann Arbor, MI, United States of America

Hyeun Joong Yoon