My cat developed diabetes this year. She’s 16 years old and has become lethargic, even more than is normal for an old cat. The vet diagnosed diabetes and I now need to give her an insulin shot twice a day, right after I feed her. So far, her diabetes has been relatively easy to manage. Initially, I took her to the vet every two weeks to check her glucose levels, and we quickly converged on a regimen. Each trip proved traumatic for the cat, who didn’t understand what was happening. Before starting on insulin, she’d become listless and had no energy. She was losing weight. Insulin brought her back from the brink.
It’s one thing for a cat to have diabetes. Now, imagine the trauma if it’s your young child who’s become listless and has started losing weight, but can’t tell you what’s wrong. Through blood analysis, you may discover that your child may have developed type 1 diabetes (T1D), an autoimmune disease that prevents the body from making insulin. T1D arises when insulin-making cells in the pancreas die and the body can no longer manufacture the essential hormone. There’s no cure for T1D and you do not grow out of it. Insulin therapy is the only treatment to date.
Insulin was discovered by Sir Frederick Banting, Charles Best, and JJR Macleod at the University of Toronto in 1921 and was first used to treat diabetes in 1922, just over 100 years ago. Insulin therapy is considered one of the greatest medical breakthroughs in history, and Banting and Macleod jointly won the 1923 Nobel Prize in Physiology or Medicine for its discovery. Over the next century, insulin therapy saved millions of lives around the world and served as the trigger for more diabetes research and additional discoveries.
However, conventional insulin therapy for T1D has its drawbacks. You start pricking the child’s finger every day to take glucose samples and injecting insulin, trying to maintain a proper glucose level by estimating the amount of insulin that the child will need, and you’re likely to have an uncooperative child who doesn’t like needles. Who does? In addition, children don’t eat on a regular schedule. Sometimes they’re picky and won’t eat at all. Sometimes they want something sugary.
Maintaining a proper insulin regimen for a child with diabetes is a nightmare for many parents. Insulin treatment has a very narrow therapeutic window. Too much insulin can induce hypoglycemia and can lead to seizures and death. Too little insulin can cause hyperglycemia, which can lead to blindness and kidney failure. People with T1D live on a knife edge, with death on either side.
There is now a better technological solution to the challenges of insulin management for T1D. It combines a wireless, wearable glucose sensor with a wireless, wearable insulin pump. The two devices communicate with each other and with a mobile phone app via Bluetooth. This PAN (personal area network) system samples a person’s glucose levels every five minutes and directs the insulin pump to administer medication accordingly. Glucose levels can be monitored on the phone app. Patients and parents can get a good night’s sleep for once.
Insulet’s Omnipod 5 system samples glucose levels every five minutes and directs the insulin pump to administer medication accordingly. Image credit: Insulet
Last month at NXP Connects in Santa Clara, California, Dr. Trang Ly discussed the challenges of treating juvenile diabetes. Ly is a Senior Vice President and Medical Director at Insulet, a medical equipment company specializing in diabetes treatment. She’s also a pediatric endocrinologist. Insulet’s founder, John L Brooks III, started the company 23 years ago because his young son had developed juvenile diabetes. Brooks, an entrepreneur, wanted to develop a better way to treat the disease and to free his son from the burden of daily insulin injections. He conceived of a wearable pod that would administer insulin in regular doses throughout the day, guided by equally regular glucose monitoring.
Company lore says that Brooks sketched the design for the first such pod on a napkin. Now, 23 years later, Insulet markets a wearable, disposable, tubeless insulin pump called Omnipod 5, which can administer small, incremental insulin doses over a 72-hour period. Then the pod needs to be replaced. The Omnipod 5 is paired with a wearable Dexcom continuous glucose monitor (CGM) to create an automated diabetes treatment system. The two devices, sensor and pump, communicate over a Bluetooth Low Energy (BLE) link and can also communicate with a Smartphone running an appropriate app for monitoring purposes. The CGM samples the wearer’s glucose level every five minutes, and the Omnipod 5 pump then administers an appropriate dose of insulin based on the most recent glucose reading.
Ly explained that the FDA considered this type of automated insulin therapy to be too dangerous a decade ago, and Insulet had to work with the regulators to get trials approved. Fast forward to today and, after five years of development, the Omnipod 5 is available in 24 countries. Its use is not limited to children. The same system works for adults with T1D, some of whom have been dealing with diabetes for decades.
Ly discussed Insulet’s Omnipod during the NXP Connects keynote session because Insulet uses NXP’s BLE-enabled SoCs in the Omnipod’s design and has worked with NXP for more than a decade. Coincidentally, NXP announced its latest wireless IoT platform and the NHS52Sx4 Bluetooth LE 5.3 processor family specifically for these kinds of applications. The NHS52Sx4 processor family was designed for battery-powered, miniaturized, wearable medical devices like the Insulet Omnipod 5, which require ultra-low-power operation, high integration levels, and flexible battery support. This processor family is based on 32MHz Arm Cortex-M33 microprocessor cores with Arm’s TrustZone security. The processors also incorporate 1 Mbyte of Flash memory and 128 kbytes of RAM. A QSPI interface permits memory expansion using external Flash devices.
Wearable medical devices like the Insulet Omnipod 5 are manufactured well ahead of use and are stored in hermetically sealed packages to maintain sterility. The battery is sealed in the package at the same time. These devices may sit on the shelf for long periods before they’re put into use. NHS52Sx4 processors draw less than 100nA in shelf mode, which extends the shelf life of the device’s integrated battery. NXP estimates that devices based on the NHS52Sx4 processors can have a shelf life of 18 to 24 months. Of course, that estimate is only for the processor’s influence on battery life and does not include other components in the end product that might also draw current. That estimate also does not include the shelf life of any medications packaged with the product. The NHS52Sx4 processor family also has low operating current and draws only 12mA when the BLE transmitter and receiver are operating.
There are two processors in the NHS52Sx4 family. The NHS52S04 processor includes a buck voltage regulator and accommodates supply voltages as high as 3V. The NHS52S14 incorporates a boost voltage regulator and accommodates supply voltages as high as 1.5V. The NHS52S04’s buck regulator allows the use of 1.7V lithium-ion cells for power and the NHS52S14’s boost regulator accommodates 1.1V silver-oxide cells.
Security is extremely important with medical devices that have wireless connections. These devices are susceptible to hacking attempts. One need only imagine the horrors of a hacked insulin pump and its possibly deadly effect on the wearer. To bolster device security, NXP incorporated a PUF (physically unclonable function) to generate device-specific secure keys. The processors also incorporate a cryptographic accelerator for secure communications.
In addition, wearable medical devices need to be small, to be as unobtrusive as possible. Nobody likes to advertise that they’re receiving continuous medication. Kids certainly don’t want to be teased about this. So NXP packaged the NHS52Sx4 processor family in small form-factor packages measuring 6.5 mm2.
Medical applications envisioned for the NHS52Sx4 processor family include wearable monitors and pumps that use skin patches to interface with the wearer, smart inhalers, hearing aids, and vital-sign monitors. One need spend only a single night in a hospital hooked up to a wired monitor to appreciate the freedom afforded by a wireless vital-sign monitor. During a conversation at NXP Connects, Mattias Lange, VP and GM for Personal Health at NXP, suggested that wound care might be the next frontier for these devices.
Wearable medical devices like Insulet’s Omnipod 5 can make a huge beneficial contribution to a patient’s quality of life, and to the lives of the patient’s family members. They can also reduce the burden on an already overtaxed healthcare delivery system. Hearing aids have been improving the lives of wearers for many decades, and there’s a quiet revolution in wearable hearing instruments going on right now. More outlets including pharmacies and mail-order companies are offering hearing instruments at lower and lower prices. Processors like the NXP NHS52S04 and NHS52S14 can be expected to contribute to the further development of such devices by making their design easier than ever.