Cool Tech from CES 2024

It’s January and that means it’s time for CES launches. I am sure most of you would be tired of the CES coverage and overuse of the word “AI” over the last few days. When reading through many CES articles with the usual tech upgrades, I found a small gem that didn’t get much attention.

The company is called Eclypia which is into developing non-invasive reliable continuous glucose monitors. An accurate non-invasive glucose monitor is supposed to be one of the grails of medical tech problems many companies are trying to solve. The current state of the art is still pinprick blood draw or a prohibitorily expensive needle patch which needs to be replaced often. So folks with diabetes are still looking for solutions that can measure their glucose levels.

According to a white paper by Eclypia, the wearable device has infrared red lasers illuminating the skin. This excites the glucose molecules in the skin, which creates a thermal signal as they return to their normal state. This signal is amplified by a photoacoustic cell and then picked up by a microphone. So they have only tested this in a digital twin in an in-silico or a simulated computer clinical trial. They use this simulated clinical trial to create a synthetic dataset to fine-tune their deep-learning algorithms. I see that they have registered for a few in-person clinical trials online. The full results of it are not out yet and the paper claims a promising error rate of 18.4%. I wish them all the best for a larger clinical trial. It’s high time that someone finally cracks this problem once and for all.

What was your favourite CES tech this year?

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Back to Basics: LEDs: Part 6: PWM Dimming

PWM Dimming LEDs
PWM Dimming LEDs

One of the key ways of dimming LEDs is via PWM dimming. At its core, PWM dimming involves rapidly turning LEDs on and off at a specific frequency. The ON time aka the duty cycle of the PWM signal, determines the average current through the LED. Usually, the LED driver is driven by a microcontroller’s PWM pin. The microcontroller can control three main parameters of the PWM signal. First is the duty cycle or the ON time. Higher the ON time, more the current, brighter the LED intensity.

Second is the frequency of the PWM signal which determines the rise and fall time of the LED current at the output of the driver. You will mostly find a ripple current at the output of the LEDs in an approx triangular fashion. If the frequency is excessively high, the LED might not reach its peak current, leading to diminished dimming/contrast ratios. If any frequency below 150Hz(approx) is used, the human eye will be able to pickup the flickering of the LEDs and cannot be used in lighting use cases. Yet, in specialized scenarios such as using LEDs for high-speed camera imaging(lower exposure rate), flickering becomes visible if a lower rate is used. Another way to mitigate the flicker is to sync the shutter speed of the camera with the LED PWM frequency although this option is often limited to scientific cameras. Hence, your choice of PWM frequency should align with your application’s demands.

Thirdly, let’s talk about PWM resolution, dictating dimming precision or how finely you can control brightness levels. An 8-bit resolution offers 256 levels of brightness, while a 10-bit gives you 1024 levels. PWM resolution is often inversely related to PWM frequency for most microcontrollers. This means you can have a high PWM frequency with lower resolution and vice versa, finding the right equilibrium is key.

In essence, mastering PWM dimming involves this intricate dance between duty cycle, frequency, and resolution, each parameter finely tuned to cater to the unique demands of your application.

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