After announcing three preventative healthcare products in November 2017, the MAX86140 and MAX86141 optical pulse oximeters and heart rate sensors and the MAX30001 ECG BioZ AFE, Maxim Integrated presented these continuous monitoring solutions at January 2018’s CES in Las Vegas, Nevada.
In a November press release, Maxim said health-monitoring technology is shifting “away from a reactive monitoring approach to a proactive one,” and this is exactly what they hope to address with their new sensor solutions.
According to Andrew Baker, Maxim's Executive Director of Business Management for Industrial and Healthcare, instead of treating symptoms when they crop up, Maxim aims to “find solutions that enable a healthier world” from the get-go.
“Obviously, there are devices already existing that monitor chronic diseases, but the thing that we’re doing is taking those type of devices, miniaturizing them, and making them more available for continuous monitoring,” he told AAC.
In doing so, Maxim hopes their products will help engineers build wearables that can nip health concerns in the bud before they become problematic down the road. This marks a mission to address larger healthcare concerns in addition to being responsive to industry trends by making components (and hence devices) smaller, lower power, and more affordable.
A diagram of the MAX30001. Imaged courtesy of Maxim Integrated.
Meet the MAX30001
The MAX30001, according to Maxim, uses about half the power that competitive solutions require—at about half their size. Primarily for measuring ECG and BioZ on the chest and wrist, it continuously monitors heart rate, heart rate variability, and pulse oximetry.
Baker says the MAX30001 is the first of its kind in the industry. Because most EKGs are used for bedside monitoring, “we took that technology and put in our secret sauce.”
This “secret sauce,” which meets clinical ECG standards, includes Maxim’s low-power solutions.
In addition, the MAX30001 runs an algorithm that Maxim developed in-house. Baker said this algorithm was based on similar ones in the industry, but theirs is implemented within the hardware doesn’t have to run on a microcontroller. This lets the MAX30001 run on lower power without waking the MCU.
A diagram of the MAX86140/MAX86141. Image courtesy of Maxim Integrated.
Enter the MAX86140 and MAX86141
Intended for measuring PPG signals on the wrist, finger, and ear, the MAX86140 and MAX86141 require even less power at a smaller size, specifically 2.048 mm by 1.848 mm with a 0.4 mm ball pitch in a wafer-level package. “But It’s not only about low power,” Baker said. “It’s also the accuracy and validity of the data you acquire.”
These sensors track the waveforms of PPG signals continuously, compiling a larger amount of data than, say, a spot-checking cellphone application, which Baker says begets higher accuracy. Essentially, the more data the sensor collects, the more trends that can be identified in the swath of readings.
“The detection is based on AI or machine learning,” Baker said. “The dataset really dictates the accuracy of the algorithm.”
On top of this, these optical sensors come with a built-in “picket fence” algorithm. According to Baker, one of the main problems with wearable sensors like the MAX86140 and MAX86141 is that they could be susceptible to ambient rejection because of intermittent sunlight or artificial light. ”So, the worst case scenario is that you’re running through a forest and go alongside a picket fence, and you get the strobe effect,” Baker says. This input confounds the data interpretation process.
The picket fence algorithm combats this problem. The signals from outside light are extracted so the sensor can keep pace with the wearer’s heart rate or running cadence.
Medical Device Security
With all of this personal data tracked and logged, one of the main areas of concern that comes with these sensors is security. “Talk to anybody about this, and that’s one of the first things they ask: security and the integrity of the data,” Baker said.
Maxim addresses this problem with their ChipDNA secure authenticators, which Baker says are up to monetary transaction-grade encryption standards. Maxim markets their authenticators with the phrase “You can’t steal a key that isn’t there.”
Three use cases for ChipDNA secure authenticators. Image courtesy of Maxim Integrated.
According to Maxim’s product page for these ChipDNA authenticators, “A key derived from a physically unclonable function (PUF) provides an unprecedented level of protection against invasive attacks since the key does not exist in memory or another static state.”
Each key is a “precise analog characteristic of the IC.” Baker says this makes each key unique to the sensor.
Maxim's health-monitoring sensors can be implemented in several different wearable and mobile devices. Image courtesy of Maxim Integrated.
Applying Maxim’s Health-Sensing Solutions
Baker said Maxim is not necessarily working with medical researchers on their sensors, save for on a selective basis. Instead, they are looking specifically for other companies to partner with and create usable end products, like SKIIN’s smart underwear.
“The convergence of clinical grade diagnostics in form factors small enough to integrate into all sorts of smart, everyday clothing is impressive,” said Adrian Straka, director of hardware and manufacturing at SKIIN. “The ultra-small MAX30001 enables SKIIN’s bio-sensing underwear to monitor and track health metrics 24 hours a day, seven days a week in low-power operation.”
Baker noted that Maxim often seeks out smaller companies to work with “because the bigger companies tend to be slower.”
Maxim's MAXREFDES100, otherwise known as the hSensor. Image courtesy of Maxim Integrated.
While Maxim is not an end-product manufacturer, Baker said the company has to build some examples of end products or what they call "mega demo" systems. “In order to showcase, we have to build end products for our customers.” This helps them show customers how their
One such end product is Maxim’s MAXREFDES100 Health Sensor, otherwise known as the hSensor. According to the product’s datasheet, the hSensor “eliminates the extra time it typically takes to develop a prototype, so you can quickly evaluate and validate the right solution for your health sensor application.”
Baker said this product is representative of a wearable an engineer could design. The left side of the hSensor is made up of optical bio-measurement hardware, and the middle includes an encryption microcontroller, along with power-management ICs. The right side of the hSensor measure ECG and BioZ.
Baker noted that the hSensor could, in one use case, be used to measure the impedance of the chest cavity on the right side and accurately measure respiration.
Maxim partnered with Suunto to build the Movesense open-source platform. Image courtesy of Movesense.
The Future of Health-Monitoring Wearables
Along with the hSensor, Maxim is working with Suunto to develop Movesense, an open-source development platform for sensing software. Baker called this an “out-of-the-box platform that [designers] can build their application on top of.” One Movesense application is a wrist device that sports the MAX86140.
“What’s unique about this particular demo is that you can stream raw data,” Baker said. “You can’t get PPG data out of other data, so you can build your algorithm to analyze the data in its raw form.”
The Impact of Affordable Sensing
Maxim is building prototypes, demos, and platforms like the hSensor and Movesense to “show what is possible” and ultimately work toward their goal of a healthier society—not necessarily “run a marathon” fitter, Baker says, but more health-conscious and preventative.
While their sensors already appear in consumer staples like the Samsung 8, Maxim hopes their continuous tracking solutions can make even more headway in the world of preventative care. Baker said Maxim’s solutions could “a huge, powerful tool” in developing countries where healthcare is not as easily accessible.
“Consumer devices are encroaching on medical devices, which is pushing the price point down,” Baker said. “Ultimately we’re trying to replace these $10,000 pieces of equipment with $100 pieces. It may not be exactly the same, but it serves the purpose of identifying issues before they become a problem.”