Optimizing Battery Solutions for Medical Devices: The Superiority of Silver Oxide Technology
Introduction: Key Challenges in Medical Device Power Source Design
In medical device design, selecting the optimal battery presents critical challenges, including reliability, size constraints, and long-term stable supply. Micro batteries are particularly well-suited for medical devices due to their compact size and diverse chemistries. Maxell has been providing silver oxide batteries (SR) optimized for medical applications for over 20 years, beginning with the development of our first dedicated battery for capsule endoscopes. This technology enabled reliable power for ingestible capsules equipped with micro-cameras, meeting stringent medical reliability requirements while optimizing battery performance. Our ongoing advancements address key needs in miniaturization, high reliability, and consistent performance. For engineers facing these challenges, this paper introduces technical solutions and supply frameworks that support overcoming common design hurdles in medical devices.
In this article;
1. Silver Oxide Battery Technology: Technical Advantages
Maxell's silver oxide batteries (SR) are engineered to optimize cell performance according to the specific requirements of each device and application.
SR batteries deliver a flat voltage profile and low impedance, supporting high-current pulses required by wireless communication modules such as Bluetooth® Low Energy (BLE). Their superior energy density and proven reliability make them ideal for a wide range of medical devices, including continuous glucose monitors (CGM), wearable drug delivery systems, and vital monitoring patches.
The following are general requirements for batteries in those medical devices.
- Small footprint and thinness
- Energy density
- High load durability
- Long reliability
- Safety
2. Why Silver Oxide Batteries (SR) Are Superior to Alkaline Button Batteries (LR) for Medical Devices
Silver oxide button batteries (SR) and alkaline button batteries (LR) share similar aqueous electrolyte technology and compact form factors. However, SR batteries are the preferred choice for medical devices due to their superior performance and reliability.
Maxell's SR batteries offer;
- Flat Voltage Profile: Ensures stable device operation throughout battery life.
- Low Impedance: Supports high-current pulses required by BLE and other wireless modules.
- Superior Energy Density: Enables longer device operation in compact form factors.
- Proven Medical Reliability: Extensive track record in applications such as capsule endoscopy and CGM.
Table. Battery Design Comparison SR/LR
| Chemistry | Zinc Silver oxide | Zinc Manganese dioxide |
|---|---|---|
| Cell Designation | SR | LR |
| Nominal Voltage | 1.55 V | 1.5 V |
| Positive Material | Silver oxide | Manganese dioxide |
| Negative Material | Zinc | Zinc |
| Discharge Property |
 |
 |
| Energy Density∗ | 448 Wh/L | 289 Wh/L |
| General Features |
|
|
| Application |
|
|
∗ The energy density is general value when it is considered SR/LR44 size (D: 11.6 mm x H: 5.4 mm).
3. Case Study: Customized Battery Solution for Capsule Endoscopy
This technical advancement enables longer device operation, enhances reliability, and supports more sophisticated medical diagnostics. Maxell's expertise in custom battery development allows us to provide tailored solutions for diverse medical device requirements.
Technical Challenge:
Capsule endoscopy devices require compact batteries capable of delivering high pulse currents and long operating times, while meeting strict reliability standards.
Conventional Battery Limitations:
Standard silver oxide batteries (SR927W) often struggle to meet the demanding discharge profiles of capsule endoscopes, resulting in limited operating capacity and reduced device performance.
Maxell's Customized Solution:
To address these challenges, Maxell developed the New SR927 battery, specifically engineered for capsule endoscopy applications. Through optimized electrode design and advanced electrolyte formulation, SR927 -- customized for capsule endoscopy -- achieves superior pulse load durability and extended discharge capacity.
Performance Comparison:
As shown in the graph below, the custom SR927 for capsule endoscopy delivers approximately twice the discharged capacity compared to conventional SR927W (catalog product) under a high-current discharge profile representative of capsule endoscope application, which includes short 10 mA pulses over a constant base current.
Impact and Customer Value:
This technical advancement enables longer device operation, enhances reliability, and supports more sophisticated medical diagnostics.
Note: The SR927 battery data presented in this case study reflects customized specifications developed for capsule endoscopy applications. These specifications differ from standard catalog products. Please consult Maxell for details and availability regarding custom battery solutions.
Figure. Battery performance comparison
4. Design Guidelines for Engineers
Selection Criteria:
Choose battery size and capacity based on the device's load profile and required operating time. Medical device applications often involve complex and variable load conditions, making accurate battery selection critical for device reliability.
Integration Tips:
Begin by selecting the appropriate battery type for your application, then carefully consider key design factors such as pulse load requirements, voltage drop, impedance, and pulse durability in your circuit design. These factors can significantly impact device performance and safety.
Consulting Support:
Battery selection for medical devices is highly complex and can directly affect the reliability and safety of your product. Early collaboration with Maxell's technical team is essential to ensure optimal battery performance and regulatory compliance from the initial development stage. Maxell offers technical consultation and custom battery solutions tailored to your unique device requirements.
Contact Us:
For engineers and developers, we strongly recommend contacting Maxell at the earliest stage of your project. Our experts can support you in navigating the complexities of battery selection, integration, and certification, helping you achieve the highest standards of reliability and performance in your medical device.
Please contact us at https://biz.maxell.com/en/primary_batteries/inquiry_form_input1.html for more information or visit us at https://biz.maxell.com/en/batteries/.- Bluetooth is a registered trademark of Bluetooth SIG, Inc.
