Modern people have relatively rich life, but diseases such as hypertension and diabetes have also become common diseases of modern people. Wearable medical devices can be used to monitor physiological state of patients and manage physical state of bodies. They function as important devices to maintain patients' health and improve quality of life. These wearable medical devices must have small size and light weight, and meet the needs of supporting high current and long service life, so high-drain button cells become the best partner for these wearable medical devices. This article introduces the development of new blood glucose monitors and the product characteristics of the high-drain button cells of Murata.
Traditional Manual Blood Glucose Monitoring Program Is Characterized by Low Convenience, Low Accuracy and Low Timeliness
Economic development brings people not only prosperous life but also some "diseases of civilization", such as diabetes. These diseases have become common diseases of modern people. According to the "2021 Diabetes Atlas 10th edition" of the International Diabetes Federation (IDF), the number of global diabetic patients in the world has continued to increase in the past 10 years, exceeding 500 million, and this number is expected to increase further in the future. The number of Chinese diabetic patients has increased from 90 million to 141 million, accounting for 26% of the global diabetic patient population. Therefore, how to monitor and manage blood glucose will be a major issue facing the human society.
Traditional manual blood glucose monitoring program was quite inconvenient, inaccurate and untimely for diabetic patients. In the past, diabetic patients at home mainly used a blood glucose meter to collect fingertip blood regularly to test the blood glucose level of capillaries. If the blood glucose level exceeded the value recommended by a doctor, the patients must manually inject insulin to control the blood glucose level. This old method was both "inconvenient" and "inaccurate", because the blood glucose level of a human body changes frequently and significantly in a day, and the regular blood glucose test at individual time points cannot accurately reflect the real blood glucose level. In addition, the precision of manual insulin injection volume is difficult to control. With such disadvantages, even if insulin can be supplemented, patients must strictly control their diet and the quality of their life has not been improved.
Artificial Pancreas Improves Quality of Diabetic Patients' Life
Nowadays, with the development of technology, scientists and technical engineers have developed an intelligent wearable "artificial pancreas" device. This continuous glucose monitoring (CGM) device, also known as an "artificial pancreas", works by implanting the CGM's sensing probe under the skin. This sensing probe can automatically detect the blood glucose level in a human body in real time and send the data to a computing unit (a dedicated PDA or an app on a mobile phone) through a wireless network. After calculating the required insulin volume, the computing unit sends an instruction to the intelligent insulin pump. The insulin pump starts and accurately injects the required insulin volume into a patient's body in real time. This helps dynamically maintain the blood glucose level of the patient in real time. By uploading data to the medical cloud platform, relevant medical institution or attending physician can master the patient's blood glucose status at any time, and give medical advice and plans in time. This whole process does not require patients' intervention, which achieves "convenient and precise" control of blood glucose level. While wearing the "artificial pancreas", patients can eat and play as normal persons, which improves the quality of their life.
The goal of medical-oriented intelligent wearable devices is to achieve full automation, high precision, and timeliness. Therefore, they have higher requirements for batteries. Compared with consumer electronic products, medical electronic products require complete functions and high precision. Regarding power supply requirements of the products, the discharge performance of the batteries must be high enough so that the medical electronic products can withstand instantaneous fluctuations in the power in a complex environment where functions such as wireless communication and hydraulic pump motor drive are also required. In addition, due to higher requirements for the reliability, stability and safety of wearable devices, the battery in the device needs to be safe, and the battery needs to be thin enough. On the other hand, the conventional requirements of the intelligent wearable devices for batteries: lightweight and thinness pose higher requirements for the specifications of the batteries.
High-Drain Button Cells Can Meet Requirements of Wearable Medical Devices
Since the launch of wearable devices 20 years before, Murata has built a significant market. By 2021, the shipment volume approximated to 500 million. The development in sound processing, biometric sensing, speech-assisted technology, wireless connection, and power management will see a substantial growth in the next-generation hearable devices (intelligent in-ears devices). However, the design and development of the hearable devices face a series of challenges.
The wearable device market is facing challenges such as miniaturization and efficiency, safety and reliability, and data transmission. These features and functions needs high-current button cells can be applied to products such as hearable devices, smart watches, AR glasses/VR helmets, and medical devices.
The SR/LR series high-drain button cells developed by Murata are ideal for devices that withstand high-current loads and provide functions such as communication, lighting, camera, and mechanical drive. The maximum pulse discharge current of the SR/LR series high-drain button cells is about 3 times of that of the standard button cells. The output current can be provided stably at 23°C when the voltage is not less than 1.2V. Therefore, the high-drain button cells can also be used in devices that must reach current peaks.
These small and thin high-drain button cells meet the miniaturization requirements of wearable devices. Processed and sealed by Murata's special sealing materials, the high-drain button cells achieve excellent leakage resistance. With the characteristics of large current load, small form factor, thinness, and high safety, the high-drain button cells apply to devices that have requirements for miniaturization, high performance and high reliability. In the medical field, the high-drain button cells can be applied to products such as drug delivery system, capsule endoscopy, insulin pump and pens, and continuous blood glucose monitor. They can also be used in Internet of Things (IoT), laser pens, audio processors.
Medical-oriented High-Drain Button Cells
The Japanese-made SR/LR series high-drain button cells of Murata consist of SR series silver oxide cells and LR series alkaline manganese cells. They are oriented to the medical field and characterized by high current, high safety, mercury-free, small form factor, light weight, and thinness.
Compared with conventional standard button cells, the SR/LR series high-drain button cells can discharge higher current. The maximum pulse discharge current of the SR/LR series high-drain button cells is about 3 times of that of the standard button cells. The output current can be provided stably at 23°C when the voltage is not less than 1.2V. At DOD 0% and 23°C, the high-drain button cells can provide the maximum pulse discharge current for 100 ms when the voltage is higher than 1.2V. This makes the high-drain button cells able to withstand the instantaneous power of the wireless modules or motors in blood glucose monitors and insulin pumps.
In addition, the SR/LR series high-drain button cells can provide longer discharge current than the conventional standard button cells. In the entire discharge process, the voltage and power of the high-drain button cells are fuller, making wearable devices operate more stably, which improves user satisfaction.
In terms of safety technology, Murata high-drain button cells do not contain harmful substances such as mercury. They can meet the safety requirements of medical materials. With the unique "J-shaped gasket" design, Murata high-drain button cells demonstrate excellent leakage resistance, which ensures the reliability, safety and durability of the cells after they are used or stored for a long time.
Murata has accumulated years of button cell application experience and a considerable number of successful cases in the field of medical devices. Medical devices equipped with Murata button cells can pass rigorous medical device certifications inside and outside Japan. In addition to continuous blood glucose monitor and intelligent insulin pump in "artificial pancreas", Murata button cells are also applied in other advanced medical devices such as "capsule gastroscopy" (digestive tract image detection) and "vibration capsules" (physical therapy of constipation).
The specifications of Murata SR/LR series high-drain button cells are as follows:
SR927R: nominal capacity: 45 mAh; diameter: 9.5 mm; height: 2.7 mm; weight: 0.70 g; rated voltage: 1.55 V; compliant with IEC (JIS) SR57 specifications
SR44R and LR44R: nominal capacity: 150 mAh; diameter: 11.6 mm; height: 5.4 mm; weight: 2.2 g (SR44R) and 2.0 g (LR44R); rated voltage: 1.55 V (SR44R) and 1.50 V (LR44R); compliant with IEC (JIS) SR44 (SR44R) and LR44 (LR44R) specifications
The working temperature of these three products ranges from -10°C to 60°C.
Conclusion
Wearable medical devices can monitor the physiological characteristics of patients with chronic diseases at any time and give medicine or warning in time, which improves the effect of medical treatment and the quality of patients' life. Their application market is quite vast. The Japanese-made SR/LR series high-drain button cells of Murata are characterized by high current, high safety, mercury-free, small from factor, light weight, and thinness, being the best partner of wearable medical devices.