Tim Bushnell, PhD
Tim Bushnell, PhD

Tim Bushnell holds a PhD in Biology from the Rensselaer Polytechnic Institute. He is a co-founder of—and didactic mind behind—ExCyte, the world’s leading flow cytometry training company, which organization boasts a veritable library of in-the-lab resources on sequencing, microscopy, and related topics in the life sciences.

Articles Written By Tim Bushnell, PhD

Avoid Flow Cytometry Faux Pas: How To Set Voltage The Right Way

By: Tim Bushnell, PhD

There are 4 major ways to sort cells. The first way can use magnetic beads coupled to antibodies and pass the cells through a magnetic field. The labeled cells will stick, and the unlabeled cells will remain in the supernatant. The second way is to use some sort of mechanical force like a flapper or air stream that separates the target cells from the bulk population. The third way is the recently introduced microfluidics sorter, which uses microfluidics channels to isolate the target cells. The last method, which is the most common––based on Fuwyler’s work––is the electrostatic cell sorter. This…

Getting A New Flow Cytometer? Try Before You Buy (And 2 Other Tips)

By: Tim Bushnell, PhD

There are 4 major ways to sort cells. The first way can use magnetic beads coupled to antibodies and pass the cells through a magnetic field. The labeled cells will stick, and the unlabeled cells will remain in the supernatant. The second way is to use some sort of mechanical force like a flapper or air stream that separates the target cells from the bulk population. The third way is the recently introduced microfluidics sorter, which uses microfluidics channels to isolate the target cells. The last method, which is the most common––based on Fuwyler’s work––is the electrostatic cell sorter. This…

My 3-Step Panel Validation Pocket Guide

By: Tim Bushnell, PhD

There are 4 major ways to sort cells. The first way can use magnetic beads coupled to antibodies and pass the cells through a magnetic field. The labeled cells will stick, and the unlabeled cells will remain in the supernatant. The second way is to use some sort of mechanical force like a flapper or air stream that separates the target cells from the bulk population. The third way is the recently introduced microfluidics sorter, which uses microfluidics channels to isolate the target cells. The last method, which is the most common––based on Fuwyler’s work––is the electrostatic cell sorter. This…

Easy-To-Forget Flow Fundamentals That Thwart Bad Science

By: Tim Bushnell, PhD

There are 4 major ways to sort cells. The first way can use magnetic beads coupled to antibodies and pass the cells through a magnetic field. The labeled cells will stick, and the unlabeled cells will remain in the supernatant. The second way is to use some sort of mechanical force like a flapper or air stream that separates the target cells from the bulk population. The third way is the recently introduced microfluidics sorter, which uses microfluidics channels to isolate the target cells. The last method, which is the most common––based on Fuwyler’s work––is the electrostatic cell sorter. This…

Important Controls For Your Flow Cytometry Lab

By: Tim Bushnell, PhD

There are 4 major ways to sort cells. The first way can use magnetic beads coupled to antibodies and pass the cells through a magnetic field. The labeled cells will stick, and the unlabeled cells will remain in the supernatant. The second way is to use some sort of mechanical force like a flapper or air stream that separates the target cells from the bulk population. The third way is the recently introduced microfluidics sorter, which uses microfluidics channels to isolate the target cells. The last method, which is the most common––based on Fuwyler’s work––is the electrostatic cell sorter. This…

4 Flow Cytometry Assays For Monitoring Intracellular Processes

By: Tim Bushnell, PhD

The most common flow assay is undoubtedly immunophenotyping, in which fluorescently tagged antibodies are used to bind to cellular proteins. This allows you to determine the types of cells present. As long as there is a fluorescent reporter available, it is possible to measure biological processes using flow cytometry – especially in a phenotypically defined manner. Probably the most common of these assays is the calcium flux assay. And that is just the tip of the iceberg. In addition to calcium, it is possible to measure magnesium and zinc concentrations, reactive oxygen species, and even membrane potential using flow. Today,…

Discover The Myriad Applications Of Beads In Flow Cytometry

By: Tim Bushnell, PhD

What is the single-most important feature of a flow cytometry experiment? Arguably, it’s the stained cells that gather data about biological processes of interest. However, a flow cytometer can measure cell-like particles as well as cells, which opens the realm of cytometry to the use of microspheres. Most researchers are familiar with the 4-Cs that beads can be used for: Control, Calibration, Compensation, and Counting. Beyond the 4-Cs, many are familiar with the multiplex bead assays for measuring analytes. Today, we will take a look beyond these well-known uses and discover the myriad applications of the “Mighty Microspheres.”

We Tested 5 Major Flow Cytometry SPADE Programs for Speed - Here Are The Results

By: Tim Bushnell, PhD

In the flow cytometry community, SPADE (Spanning-tree Progression Analysis of Density-normalized Events) is a favored algorithm for dealing with highly multidimensional or otherwise complex datasets. Like tSNE, SPADE extracts information across events in your data unsupervised and presents the result in a unique visual format. Given the growing popularity of this kind of algorithm for dealing with complex datasets, we decided to test the SPADE algorithm in 5 software packages, including Cytobank, FCS Express, FlowJo, R, and the original, free software made available by the author of SPADE. Which was the fastest?

Mass Cytometry Revolves Around These 5 Things

By: Tim Bushnell, PhD

Because mass cytometry allows users to characterize masses so effectively, data can be normalized much more efficiently than what traditional fluorescent flow will permit. If there is no working CyTof at your institution, you can still partner with CyTof-friendly research institutions that have the technology on hand. And because the samples are fixed, you can ship them overnight. This way, they will be analyzed for you. Today’s article will summarize the functionality of mass cytometry technology. This tech has been commercialized largely by Fluidigm in the CyTof systems. There are 5 key points to cover, or takeaways, that cytometrists should…

Understanding Reproducibility in Flow Cytometry - It’s the Antibodies!

By: Tim Bushnell, PhD

Reproducibility is key to the scientific method. After the results of a study are published, the community validates the findings and extends them. If the findings are not reproducible, the second step is impossible. With performable experiments increasing in complexity, and the concurrent increase in the cost of equipment and reagents to perform these experiments, it is important to find the best way to maximize the money spent on advancing research. In flow cytometry, there are many places where improvements can be made to increase the consistency and reproducibility of an experiment. The most obvious place is in the instrument,…

3 Components Of Every Flow Cytometer You Don’t Know Enough About

By: Tim Bushnell, PhD

All flow cytometer instruments have a certain 3 components, and the way they are put together will dictate the performance of the system. As a user, you’ll be interacting heavily with these components, so you need to know both what they are and how they work. There are fluidics, optics, and electronics. The fluidics allow you to interact at the right flow rate so that your data keep a tight CV. Then you can run the same flow rate for all your samples, and you won't have different CVs for different samples. There are also different optics you can use,…

4 Ways To Analyze Tissues By Flow Cytometry

By: Tim Bushnell, PhD

Did you know that tissues can be measured by flow cytometry? Flow cytometry is the measurement of cellular processes at the whole-cell level. This definition is useful because it includes not only flow cytometry, but any technique that measures at the level of the whole cell. Microscopy, for instance, is a great example of cytometry. But, what can be measured by flow cytometry? For one, tissues with lots of cells. When flow cytometry is practiced, the cells are broken up. Therefore, any cellular interactions within the sample are also broken up. This includes tissues, cell-to-cell contacts in tissues, and virtually…