There are numerous benefits to using a signal conditioner, including the ability to control the amplification of the sensor using software instead of physical op-amps, minimizing the components on and the size of our circuit board. The signal conditioners can also be calibrated to allow correction for sensor offset and temperature effects. Finally, the signal conditioner incorporates an A/D converter, allowing the output signal to be transmitted in the digital formats of either I2C or SPI. The 31014 signal conditioner produced by ZMD is specially designed for resistive bridge sensors, such as our differential pressure sensor.

The BME design team met with Eric Hoffman and Isaac Wiedmann of ZMD to learn how to connect the 31014 to our existing pressure sensor and how to use the various features of the chip. Isaac also demonstrated a personal project of his that uses a differential pressure sensor to calculate the velocity of a fluid flow through a tube. In his design, a flexible plastic tube has a small constriction where the second pressure is measured, causing a larger differential pressure between the inputs. The team connected this portion of his project to their pressure sensor and expired through the tube. The ZMD software collected the output, and the data was graphed on an Excel worksheet.

Flow-time figure

We’ll add technical details to the long neglected hardware section of the wiki soon. Many thanks to David H, Eric, and Isaac.

In the meantime, we’re turning our focus to the construction of the spirometer body. Once manufactured, we will attach sensor circuitry and correlate the signal output with known air flow rates. After correlation, the spirometer will be able to measure air flows through the tube in units of L/s. The team will then create software that will use this data to calculate air flow vs. volume graphs and important measurements such as FEV1 and FVC.

The team will be giving a poster presentation on May 1st in the UW-Madison Engineering Centers Building from 12-2PM. Please come say hello and check out their prototype; you’ll also be able to check out all the other great student design projects underway this semester.

- J Glynn

For the past week we’ve been strategizing about the audiovisual materials we hope to build to demonstrate the ideas of standardizing patient preparation, instruction and coaching, including several different types of incentive screens – typically modeled on what we’ve seen in the marketplace.

During a meeting last week with Charlotte – a French student spending a year in Madison who is pitching in to help make the short clips we’ll need -the students came up with some exciting new ideas about the incentive screen.

For example, Jeremy G raised the possibility of making the screen more competitive – taking a game approach a step further.

The discussion led me to wonder whether we could create a competitive animation where the opponent depicted the student’s own predicted values (the expected values for someone of the same age, sex and height).

Charlotte suggested that we think about creatively trying to exploit and encourage the patient to model the behavior of a person demonstrated in the video.

In general, I’ve recently been wondering whether incentive screens might be better seen as something for everyone doing spirometry, rather than just for kids.

Andrew D had done some reading about incentive screens and drew our attention to a debate in the literature about their efficacy. Surprisingly, it turns out that the efficacy of incentive screens hasn’t actually been very well evaluated.

The series of articles he found reveal a small but healthy debate within the respiratory community about whether traditional incentive screens and computer animations improve the quality of measurements in young children – and which parts of the maneuvers they actually affect (effort, reproducibility).

I’ve posted some of Andrew’s comments in the wiki along with links to the articles in the resources area of the wiki. We’d love to hear what others think about the value of the incentive screens, and stimulate some discussion about innovative ways to improve their utility.

Please let us know what you think about the ideas for the incentive screens or suggest some of your own. We’re keeping a list in the wiki and will start build something in the next week or two.

Pressure sensor setup

They’ve started preparing for their upcoming mid-semester presentation on the project which will take place Friday afternoon. I hope to post some of the details of the presentation soon afterwards.

Testing differential pressure sensors

Early on I learned some interesting details about each of their backgrounds and interests and have been wanting to introduce them.

Jeremy G grew up in a little town north of Minocqua (the true Northwoods of Wisconsin) surrounded by trees and lakes and, in his words, “not much else.” He studied abroad in Ireland last semester and spends time here on outdoor activities, especially cross-country skiing in the winter.

Jeremy S is a junior from Waterford, WI, interested in bioinstrumentation and medical imaging, who also gets outdoors as he can to hunt and fish.

Andrew D is a junior BME major in the bioinstrumentation track, who’s made it his goal before graduation to finish a Mickey’s scrambler in one sitting.

Andrew Bremer is a junior studying BME at UW-Madison. Outside of school he is an officer in the UW chapter of the Biomedical Engineering Society and also works as a campus tour guide. Born and raised in Madison, he is a true Madisonian – he enjoys Badger sporting events, Babcock ice cream, (the World’s Largest) Bratfest, cheese, Concerts on the Square, hanging out on the Memorial Union Terrace, and all other things that make Madison unique!

Thanks to each of them for their enthusiasm and hard work so far this semester.

Spirometry team members in the lab

A team of UW-Madison biomedical engineering students have decided to spend the semster working on the spirometry project for their applied design course.

The four undergraduate students began last week with a trip to the spirometry lab. The team is taking apart old spirometers and doing background research as they develop a preliminary specification.

This is my second time working with BME students and I’m looking forward to seeing how the group rises to the challenge. These are all bright, motivated individuals who think creatively and work hard all semester to develop some creative and exciting products together.

Their participation in the OpenSpirometry project is a great start and a big step forward. Thanks to each of them for deciding to take it on. I’ll post a profile of the team in the days to come.

I’m happy to report that there are several teams working on low-cost medical solutions this semester, with guidance from two extraordinary BME graduate students.

Please welcome the team as they get started on the project and hopefully take advantage of the site to post questions and materials as they go along.