Posts by Kenneth MacCallum

Kenneth MacCallum

Designing BLDC motor drive electronics

Brushless, direct current (BLDC) motors are one of the options for motion control solutions in medical device development. BLDC motors typically offer higher power, higher efficiency, and lower wear than comparably sized motors of other types. The main challenge in incorporating these motors is the complexity in the drive electronics and control strategy. As an […]

Kenneth MacCallum

Strategies to Maximize Medical Device Optical Signals

A common challenge when designing medical devices that make optical measurements is ensuring the optical system state remains correlated with sensor measurements in order to maximize medical device optical signals. The sort of device I’m speaking of achieves its measurement by illuminating something and collecting the scattered or transmitted light. For this conversation, that “something” […]

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

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.

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