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 […]
Posts by Kenneth MacCallum
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 […]
CPU modules are off-the-shelf PCBs that combine a powerful microcomputer, support circuits and a number of key peripherals with their electrical connectivity provided by board-to-board connectors. This makes them perfectly suited to be incorporated onto a custom PCB in a medical device or IVD.
Open Source Software (OSS) is software with a copyright license that includes the right to view and alter the source code and to distribute derivative works. Usually, OSS is available free of charge and therefore offers the possibility to get a significant head start on your medical device development.
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 […]
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.
I find myself regularly designing motion control systems as part of the internal mechanisms of Medical Devices. There are predominately two types of motors that I use nowadays: DC motors and stepper motors. I find that knowing a little bit about how each of these motors operate and how they are typically used makes it […]
Prior to constructing ultrasound images out of raw radio-frequency (RF) data, the transducer pulse frequency must be removed from the data to prevent ripple artifacts in the image. There are a number of methods of demodulation in ultrasound although two ultrasound signal processing techniques are used predominately nowadays.
Last week I shared ideas, tips and suggestions that I believe increase the chances of being successful when designing printed circuit boards. Here’s a few more that come to mind.
I’ve been designing printed circuit boards for years now and have learned plenty of things I believe increase the chances of being successful. Here’s a handful of PCB Design Best Practices that come to mind. And another handful will appear in part two of this blog next week.
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 […]
Working on medical devices involves a lot of science, regulation, process and other things that often don’t appeal to executives, entrepreneurs, or my children. On the other hand, my three year old son is really keen on trains.