Posts by Kenneth MacCallum

Kenneth MacCallum

Temperature Measurement and the Application of NTC Thermistors 

When I say temperature sensors, you’ll likely think thermocouples. But today I’d like to discuss NTC thermistors. Medical devices regularly need to measure  temperature. Often engineers overlook or under-estimate the inherent challenges. Whether designing in thermal measurement and control capability or just temporarily instrumenting up a test rig, it’s worth thinking about how the device […]

Kenneth MacCallum

How to improve sensor measurement accuracy in Medical Devices

Using Matched Filters  Anyone who has taken a signals and communications course has likely heard of matched filters. Intuitively these filters use knowledge of the form of a transmitted signal to pull it out of the noise. Matched filter theory or related concepts are commonly used in RF communication but I often apply it to […]

Kenneth MacCallum

5 things to consider when using Asynchronous Serial Protocols in medical devices

In many medical devices, especially those that are microprocessor controlled, it is common for programmable subsystems to communicate via asynchronous serial protocols. Such subsystems include things like programmable power supplies, syringe pumps, temperature controllers, motor controllers and smart linear actuators. I’m often surprised by how many of these devices have poorly thought-out protocols that make it […]

Kenneth MacCallum

Safety and business implications for lithium batteries in medical devices

Lithium rechargeable batteries achieve some of the highest energy densities available today. Not surprisingly, medtech companies are keen to use lithium batteries in medical devices and benefit from reduced weight or increased battery life. There are a number of safety implications to choosing these batteries as well as practical business implications.

Kenneth MacCallum

4 Tips for using floating point computations in firmware

Digital Health: Floating Away Until very recently I would never have dreamed of using floating point computations in firmware. It required too heavy a penalty in code space and computation time. Suddenly the game changed considerably.  Now there are a number of relatively inexpensive microcontrollers which have single-precision floating point capabilities implemented in hardware. Here […]

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