Technology is transforming the industrial sector, especially HVAC. Customers now expect seamless connectivity, and this shift is creating new opportunities for recurring revenue. The reason is simple: to enable predictive maintenance (such as detecting component failures),  efficient energy consumption, continuous monitoring, and remote control. 

Various manufactures are capitalizing on this by offering subscription-based remote monitoring services, typically charging a few dollars per month per device. Since recurring revenue (RR) is valued higher than one-time sales, this model can drive shareholder value faster and more sustainably.

Another major challenge in the industry is balancing cost reduction with quality improvement. In manufacturing, variations in components and environmental factors can impact product performance, requiring real-time adjustments. Smart applications that enable precise calibration during assembly streamline production, improve efficiency, and enhance reliability. This not only helps manufacturers reduce waste and increase output but also strengthens the value they offer to customers.

Beyond boosting initial product sales, connected solutions open the door to additional revenue streams. Take a heating and cooling system, for example. With sensors that monitor temperature, maintenance needs, and calibration adjustments, manufacturers can provide customers with a robust, data-driven service that ensures peak performance and extends the lifespan of their equipment.

A Smarter User Experience

A well-designed user interface (UI) for a connected industrial solution should offer:

• Real-time system monitoring: Providing visibility into temperature, humidity, and operational status.
• Predictive maintenance alerts: Notifying users of potential failures before they happen.
• Remote control capabilities: Enabling users to adjust settings and optimize energy consumption from anywhere.
• Historical data and analytics: Offering insights into performance trends and efficiency improvements.

What’s Next?

Every company and product is unique and product expansion requires thoughtful planning. Whether you need help defining your roadmap, optimizing your technology, or executing your engineering strategy, we’re here to assist.

By embracing connectivity and subscription-based services, industrial companies can unlock new opportunities for growth, improve customer satisfaction, and stay ahead in an increasingly competitive market.

Creating healthcare solutions in the cloud requires a comprehensive approach to ensure compliance with stringent regulations while utilizing advanced technologies for robust, scalable, and secure services. This article delves into essential aspects of developing healthcare applications in the cloud, including the necessity of Business Associate Agreements (BAAs), common cloud services, architectural choices, and security considerations.

The Necessity of Business Associate Agreements (BAA) with Suppliers

In the healthcare industry, protecting patient data is critical. A Business Associate Agreement (BAA) is a contract between a healthcare provider and a third-party service provider, ensuring that both parties comply with HIPAA (Health Insurance Portability and Accountability Act) regulations regarding the handling of protected health information (PHI). Establishing a BAA with suppliers is essential to:

1. Ensure HIPAA Compliance: Both parties must adhere to HIPAA regulations to protect PHI.
2. Define Responsibilities: Clearly outline each party’s responsibilities and liabilities regarding PHI.
3. Protect Data: Safeguard patient data from unauthorized access and breaches.
4. Mitigate Risks: Reduce legal and financial risks associated with non-compliance.

Common Services Used in Healthcare Cloud Solutions

Healthcare cloud solutions frequently utilize a range of services to meet regulatory requirements and operational needs:

• Data Storage and Management: Secure storage solutions such as AWS S3, Google Cloud Storage, and Azure Blob Storage, all offering encryption at rest and in transit.
• Computing Services: Scalable computing resources like AWS EC2, Google Compute Engine, and Azure Virtual Machines for running applications and processing data.
• Database Services: Managed database services including Amazon RDS, Google Cloud SQL, and Azure SQL Database, configured for HIPAA compliance.
• Networking: Secure networking solutions such as AWS VPC, Google VPC, and Azure Virtual Network to ensure secure data transmission.
• Identity and Access Management (IAM): Robust IAM services like AWS IAM, Google Cloud IAM, and Azure Active Directory for managing user access and permissions.
• Monitoring and Logging: Comprehensive monitoring and logging services like AWS CloudWatch, Google Stackdriver, and Azure Monitor for maintaining security and operational visibility.

Architectural Choices: Microservices vs. Monolithic Architecture

Choosing the right architectural approach is crucial for developing healthcare applications. Both microservices and monolithic architectures have their advantages and disadvantages.

Microservices Architecture

Advantages:

• Scalability: Individual microservices can be scaled independently, enhancing performance and resource utilization.
• Flexibility: Different technologies and languages can be used for different services, optimizing each for its specific function.
• Resilience: Failures in one service do not necessarily impact others, improving overall system resilience.
• Agility: Independent teams can develop and deploy services simultaneously, accelerating development and deployment.

Disadvantages:

• Complexity: Managing multiple services requires robust DevOps practices and tools, increasing complexity.
• Latency: Network communication between services can introduce latency, affecting performance.
• Cost: Higher operational costs due to increased resource usage and complexity.
• Decreased Portability: The risks of cloud vendor lock-in is higher.

Monolithic Architecture

Advantages:

• Simplicity: A single codebase and deployment unit simplify development, testing, and deployment.
• Performance: Internal function calls within a monolith are typically faster than network calls between microservices.
• Lower Costs: Simpler architecture can result in lower operational and development costs.
• Portability: Monolithic applications can be deployed on containerization platforms (e.g., Docker), which are generally cloud provider agnostic, enhancing portability across different cloud environments.

Disadvantages:

• Scalability: Scaling a monolithic application is challenging, as the entire application must be scaled, even if only one part needs more resources.
• Flexibility: Limited flexibility in using different technologies for different parts of the application.
• Maintenance: Maintaining and updating a monolithic application becomes increasingly difficult as the codebase grows.

Security Considerations

Security is paramount when developing healthcare applications in the cloud. Key considerations include the following two conditions (especially when it comes to HIPAA). 

Encryption at Rest

Encrypting data at rest protects stored data from unauthorized access. This can be achieved through:

• Cloud Provider Services: Utilizing encryption features provided by services like AWS KMS, Google Cloud KMS, and Azure Key Vault.
• Custom Encryption: Implementing tailored encryption mechanisms for specific needs.

Encryption in Transit

Encrypting data in transit protects data as it moves between systems. This involves:

• TLS/SSL: Using Transport Layer Security (TLS) or Secure Sockets Layer (SSL) to encrypt data transmitted over networks.
• VPNs: Implementing Virtual Private Networks (VPNs) for secure communication between on-premises and cloud environments.

Service Usage Implications

Certain cloud services may not be suitable for healthcare applications due to security and compliance concerns. For example:

• Suitable for Use:
  • AWS RDS: Provides HIPAA compliance when configured with encryption features.
  • Google Cloud Healthcare API: Designed specifically for healthcare data and compliance.
  • Azure Security Center: Offers advanced threat protection tailored for healthcare applications.
• Not Suitable for Use:
  • AWS Lambda without VPC: May not meet compliance requirements without proper network isolation.
  • Google Firebase Realtime Database: In some cases, lacks built-in HIPAA compliance features.
  • Azure DevOps Pipelines: Requires careful configuration to ensure compliance with healthcare regulations.

In conclusion, building healthcare solutions in the cloud requires balancing compliance, security, and architectural decisions. Establishing BAAs with suppliers, leveraging appropriate cloud services, choosing the right architectural approach, and implementing robust security measures are essential steps in creating effective and compliant healthcare applications.

In today’s digital age, the protection of patient data has become a paramount concern for healthcare organizations. With the increasing reliance on electronic health records (EHRs) and interconnected medical systems, the potential for data breaches and cyber threats has grown exponentially. Ensuring the security of sensitive patient information requires a multifaceted approach, encompassing both physical and cybersecurity measures. This article explores critical strategies for safeguarding patient data, including robust encryption, comprehensive risk assessments, and advanced network security practices. By implementing these measures, healthcare providers can enhance their defenses against evolving threats, maintain compliance with regulatory standards, and foster trust with their patients.

Educating Team

Educating your healthcare staff, especially those with access to patient data, are educated regularly (perhaps on a quarterly or bi-annual basis). These training sessions should include latest privacy regulations, possible security threats, and any refersers on how to best handle sensitive information. Enforcing sufficiently strong passwords, only having data on company-owned machines, and showing how to recognize phishing attached and the process to report suspected risk and breaches. This is the first step to protect against data breaches and misuse.

Role-based Access Control

Implement comprehensive access control measures to ensure that only authorized personnel can access or modify patient data. Employing role-based access control (RBAC) is an effective approach that assigns access permissions based on specific job roles within the healthcare organization.

For example:

• Doctors: Full access to patient medical records, including the ability to update medical histories, prescribe medications, and enter treatment plans.
• Nurses: Access to patient care information, medication administration records, and the ability to update patient vital signs and notes.
• Administrative Staff: Access to patient demographic information and appointment scheduling, but restricted from viewing or altering medical records.
• IT Personnel: Access to system configurations and maintenance logs but no access to patient medical data.

This structure minimizes the risk of data misuse by limiting access to sensitive information based on an employee’s specific responsibilities.

Additionally, it is essential to establish comprehensive audit trails that record every instance of data access and modification. These logs should capture details such as:

• User ID: Identifies the person accessing or modifying the data.
• Timestamp: The exact date and time of the access or modification.
• Action Taken: Specifies what was accessed or changed (e.g., viewed patient records, updated medication).
• Affected Records: Identifies which patient’s data was involved.

These audit trails are crucial for tracking user activity, identifying potential security breaches, and conducting thorough investigations of any unauthorized actions.

Regular reviews of access permissions and continuous monitoring of audit logs are recommended to maintain the integrity and security of patient data. Implementing automated alerts for suspicious activities, such as multiple failed login attempts or unusual access patterns, can further enhance the security of the system.

Data Encryption

Encryption is a critical tool for protecting patient data, transforming sensitive information into a code that unauthorized users cannot easily decipher. To ensure robust security, all patient data—whether stored or transmitted—must be encrypted using strong algorithms and secure keys. This includes data on mobile devices, in transit over networks, and stored in the cloud. Encrypted data remains unreadable to intruders in the event of a breach, significantly mitigating potential damage.

Different encryption methods are tailored to specific applications. One common method involves using X.509 certificates to implement Transport Layer Security (TLS). TLS typically employs the Advanced Encryption Standard (AES) for data encryption and RSA keys for secure key exchange.

Two specific encryption concepts are:

1. Transport Layer Security (TLS): This method encrypts data transmitted over the internet. It uses AES for data encryption and RSA keys for key exchange, ensuring secure communications between clients and servers. This method is crucial for protecting data in transit, such as during online transactions or when accessing cloud services.
2. Machine-to-Machine Authentication: This practice may involve using Application Programming Interface (API) keys embedded in HTTP headers or mutually-authenticated certificates. This ensures secure communication between systems, such as between healthcare devices or between applications within a healthcare network.

Additionally, it is essential to manage encryption keys securely, employing practices such as key rotation and using hardware security modules (HSMs) for key storage. Regular updates to encryption protocols and algorithms are necessary to protect against evolving threats.

By implementing these encryption strategies, healthcare organizations can significantly enhance the security of patient data, ensuring it remains protected even in the event of a breach.

Network Controls

Secure your network infrastructure against intrusions and attacks by employing a multi-layered security approach. Utilize firewalls and intrusion detection systems (IDS) to monitor and block malicious traffic. Regularly update anti-virus and anti-malware software to guard against the latest threats. Additionally, ensure Wi-Fi networks are secured with strong encryption protocols, and consider using virtual private networks (VPNs) for remote access to protect patient data transmitted over the internet.

However, relying solely on VPNs for security is no longer sufficient. High-profile cybersecurity attacks have demonstrated that once the VPN layer is breached, unencrypted internal systems can be easily compromised. To address this, adopting a zero-trust network architecture is essential. This modern approach employs security controls for every network component, not just the entry point.

Key practices of zero-trust networks include:

1. Internal Encryption: Ensure all internal communications between nodes are encrypted. For example, internal servers must use encrypted connections when communicating with databases. This prevents unauthorized access even if the network perimeter is breached.
2. Strict Authentication: Require robust authentication for all internal network components. Each internal server, database, and service must authenticate before any data exchange. This minimizes the risk of unauthorized access within the network.
3. Segmentation and Least Privilege: Segment the network into smaller, isolated sections and enforce the principle of least privilege. Limit access rights for users, devices, and applications to only what is necessary for their function. This reduces the attack surface and limits potential damage from breaches.
4. Continuous Monitoring and Logging: Implement continuous monitoring and logging of all network activities. Regularly analyze logs for unusual activities and conduct audits to ensure compliance with security policies.
5. HIPAA Compliance: Adhere to HIPAA regulations by encrypting data at rest. Ensure that stored patient data is encrypted to protect it from unauthorized access and breaches.

By integrating these practices, healthcare organizations can create a robust and resilient network infrastructure that provides comprehensive protection for patient data, significantly reducing the risk of security breaches and ensuring compliance with regulatory requirements.

Risk Assessments

Conduct regular risk assessments to identify vulnerabilities in your healthcare system. These assessments should evaluate both the physical security of data storage areas and the cybersecurity of your IT infrastructure. Identifying potential risks, such as outdated software, inadequate network protections, and insufficient employee awareness, is crucial. Use the findings to update security policies and procedures, ensuring that patient data protection measures evolve with emerging threats.

Key components of a comprehensive risk assessment include:

1. Physical Security Evaluation: Inspect data storage areas, including server rooms and physical file storage, to ensure they are secure against unauthorized access. Implement measures such as access controls, surveillance cameras, and secure locks.
2. Cybersecurity Assessment: Examine the IT infrastructure for vulnerabilities. This includes evaluating the security of software applications, network configurations, and hardware devices. Regularly update software and firmware to protect against known vulnerabilities.
3. Network Security Review: Assess the effectiveness of firewalls, intrusion detection systems, and encryption protocols. Ensure that networks are segmented appropriately to limit the spread of potential breaches and that secure communication channels are in place.
4. Employee Awareness and Training: Evaluate the level of security awareness among employees. Conduct regular training sessions on best practices for data protection, recognizing phishing attempts, and reporting security incidents.
5. Outdated Software Identification: Identify and replace or update outdated software that may be vulnerable to attacks. Ensure all systems are running the latest security patches and updates.
6. Policy and Procedure Updates: Use the results of risk assessments to inform updates to security policies and procedures. Ensure that these policies are comprehensive and address both current and emerging threats.
7. Continuous Monitoring and Improvement: Implement continuous monitoring of the IT infrastructure to detect and respond to threats in real-time. Regularly review and improve security measures based on the latest threat intelligence and risk assessment findings.

By conducting thorough risk assessments and implementing these strategies, healthcare organizations can significantly enhance their security posture, ensuring that patient data remains protected against both current and future threats.

Incident Response

Develop a comprehensive incident response plan to address potential data breaches swiftly and effectively. This plan should outline specific steps for containment, eradication, and recovery, as well as communication strategies for notifying affected patients and regulatory bodies. Regularly test and update your incident response plan to ensure its effectiveness and readiness. Quick and decisive action can minimize damage and help restore trust in your healthcare system’s ability to protect patient data.

Depending on your network architecture, different intrusion detection and prevention systems should be considered. For instance, if your solution is built on Amazon Web Services (AWS), you can utilize AWS-specific security tools. Additionally, there are several third-party solutions such as Alert Logic, Trend Micro, and McAfee that offer robust security features.

In a cloud-computing context, such as with AWS EC2 instances, it’s crucial to monitor inbound and outbound packets to detect vulnerabilities. Implementing next-generation firewalls can provide an added layer of protection. These advanced firewalls offer more than standard firewall protections by including application-level inspection, stack visibility, and intrusion prevention capabilities.

Key components of a robust incident response plan include:

1. Containment: Identify and isolate affected systems to prevent the breach from spreading. This may involve disconnecting compromised systems from the network and halting unauthorized access.
2. Eradication: Remove the root cause of the breach, such as malware or exploited vulnerabilities. Ensure that all traces of the threat are eliminated from the network and affected systems.
3. Recovery: Restore affected systems and data from secure backups. Validate that all systems are functioning correctly and securely before resuming normal operations.
4. Communication: Develop clear strategies for notifying affected patients and regulatory bodies about the breach. Transparency is key to maintaining trust and compliance with legal requirements.
5. Regular Testing and Updates: Conduct regular drills and updates to the incident response plan. This ensures that the plan remains effective and that the team is prepared to respond quickly to any data breach.
6. Cloud-Specific Measures: For cloud environments, utilize cloud-native security tools and services to enhance protection. Regularly review and update security configurations to address emerging threats.

By implementing these comprehensive strategies, healthcare organizations can better protect patient data, respond effectively to breaches, and maintain trust in their ability to safeguard sensitive information.

Conclusion

In an era where patient data security is of utmost importance, healthcare organizations must adopt a comprehensive and proactive approach to protect sensitive information. By implementing robust encryption, conducting regular risk assessments, and enhancing network security, they can significantly mitigate the risks associated with data breaches and cyber threats. These strategies not only ensure compliance with regulatory standards but also help maintain the trust and confidence of patients.

What measures are you taking to safeguard patient data in your healthcare organization? Feel free to reach out with your questions or share your thoughts on how to improve data security in the healthcare industry.

PREFACE

Building a new cellular-based product requires various technical and regulatory considerations. We will examine possible product cellular certification paths, requirements, and suggestions useful for project planning; specifically, we will examine the subject in the following order:

• Introduction
• General Regulations
• Relevant LTE Bands
• Carrier Comparisons
• Specific Carries’ Certification Flow
• Regulatory Cost Analysis
• References

INTRODUCTION

To develop a successful cellular product to market, three pillars must be simultaneously considered during project planning and execution – development, regulatory, and manufacturing. This whitepaper will address the regulatory portion.

Common questions regulatory certification groups will ask:

1. What chipset/module is the device based on? What is the FCC ID and (if applicable) PTCRB certification?
2. Will the device be used fewer than 20 cm from a person?
   1. If yes, specific Absorption Rate (SAR) Tests are required. Otherwise not.
3. Does the device have an internal or external antenna?
   1. If the cabling to antenna less than 20 cm?
      1. If yes, carrier OTA tests are required.
4. How many SIM cards are present? Are they removable or soldered?
5. What technology (i.e. LTE CAT M1) is used? What bands are enabled?
   1. A module can be programmed to only enable certain bands of interest, helping limit regulatory testing by targeting the optimal market.
6. Does the device use special command software, such as AT commands for settings or configuration?

GENERAL REGULATIONS

• FCC (All Carriers)
  • If using a pre-approved module, submission for an FCC cert or ID is not required. Instead, the FCC requires the manufacturer to put a label specifying which pre-certified module is in the device.
  • Unintentional emission tests are still required and can be performed by a third-party lab. No submission of the test results to the FCC is required. This is referred to the Suppliers Declaration of Conformity (SDoC) [1].

• PTCRB (AT&T and T-Mobile, not Verizon carriers)
  • With a pre-certified module, there are the following tests:
    • OTA (TRP, TIS)
    • RSE
    • U-SIM
  • Additional requirements require OTA and cybersecurity considerations
  • Manufacturer submitted for a PTCRB cert will still need to register device on the PTCRB website, even if using a pre-approved chipset
• Carrier specific testing (subsequently described)

Important consideration:

Not all carriers mandate PTCRB. For example, Verizon does not need PTCRB and runs its own certification process known as the open development initiatives (ODI). This process can be custom and based on the number of simultaneous radios (referred to as coexistence); the cost can be substantial for complex designs. However, if the end goal is to ensure carrier operation on AT&T or T-Mobile, PTCRB would be required.

Additionally, every three years, a PTCRB recertification is required; however, an abbreviated effort is allowed (typically one-third the original cost) if the design is unmodified. If the design is modified, such as due to an antenna change, then an engineering change order (ECO) is required, and the cost is still typically a fraction of the original certification cost.

RELEVANT LTE BANDS

CARRIER COMPARISON

A device operating on a specific carrier does not necessarily need all the possible bands, since the exact chosen bands depend on the operating location.

SPECIFIC CARRIERS’ CERTIFICATION FLOW

AT&T:

Trendi testing is the Testing Requirements for Network Ready Devices for IoT, an AT&T process. This is a 24-hour test in which the carrier sends test SMS messages to the device. The user is expected to interact with the cellular device to allow the carrier to baseline device performance and data usage.

Expected Behavior:

• Ensure devices is not aggressive when unable to reach network.
• Route device reset is permitted. However, steady state behavior must not exceed once every four hours.
• Number of authentication requests must be fewer than 19 per hour. Ideal target is fewer than 6.
  

Verizon:

T-Mobile:

REGULATORY COST ANALYSIS

The following variables impact the certification cost:

• Technology (CAT M1 vs CAT M1 + NBIoT)
• Specific Bands
• Supported Carries
• Multiple Radios
• Fallback Mechanism (if LTE not available)
• Antenna Cable Length

Carriers and specific bands impact the certification costs. Also, integrating multiple radios (Bluetooth, Wi-Fi, Cellular, etc.) require coexistence to limit radio cross talk and would increase cert cost. Note that the exact chipset that is chosen does not significantly impact the regulatory cost, if it is already pre-certified and used as an integrated device.

Pre-certification could be used during development to mitigate the final certification effort.

In general, the rough cost (on the low end) for the simplest cellular regulatory certification is in the low five-figures, taking into consideration FCC, PTCRB testing + registration, and a carrier cert. However, the exact cost varies significantly based on the exact bands and carriers that are used.

REFERENCES

[1] – FCC Supplier’s Declaration of Conformity Guide https://apps.fcc.gov/kdb/GetAttachment.html?id=cPjFB7kIR2TMlwiHUNAbvA%3D%3D&desc=896810%20D01%20SDoC%20v02.pdf

[2] – 3GPP TS 36.101 V17.1.0 (2021-03) Standard. [https://www.etsi.org/deliver/etsi_ts/136100_136199/136101/10.17.00_60/ts_136101v101700p.pdf]

• Component Selection
• Electromagnetic Interference (EMI – FCC Part 15)
• High Voltage Transients (IEC 61000-4-2)
• Battery Protection (IEC 62133)

COMPONENT SELECTION

The component selection process is often overlooked but critically important. Even two passive components like capacitors with the same capacitance values can perform significantly differently in various conditions. Besides the component value, other important device parameters include:

• Device Parasitics (inductance, capacitance, resistance)
• Operating Temperature (typical and absolute maximum)
• Operating Voltage (typical and absolute maximum)
• Operating Currents (typical and absolute maximum)
• Thermal Performance (heat dissipation – typical and absolute maximum)

Choosing elements such that they operate in environments below their absolute maximum (or minimum) ratings with a safety margin is called derating. For example, choosing a capacitor with a maximum voltage rating of 7.5 V (or higher) when the capacitor would only see at most 5 V, results in a 50% margin, which increases the reliability of the component. A 50% margin can increase Mean time between failures (MTBF) by about 30% [1]. Note that MTBF is the predicted time between inherent failures of a system during normal operation.

Furthermore, the manufacturing process needs to enforce the reliability requirements. If due to parts obsolescence or sub-standard supplier work, lower quality components with lower margin may be substituted, thereby degrading the reliability of the device (despite the upfront scrupulous design work). Therefore, requirements on the component tolerances must be communicated from the design engineering to the manufacturing engineering departments in a documented and traceable fashion for quality assurance purposes.

EMI

SOLID GROUND PLANE

An insufficient ground plane is the single largest factor for sub-par EMI performance. Using a 4-layer PCB allows for a dedicated ground layer. However, during the Printed Circuit Board (PCB) routing phase, much of the internal layer can have traces, which decreases the effectiveness of the ground plane. This is especially problematic for high frequency signals, since their electromagnetic fields will have to find another return path, thereby causing coupling issues. Since some traces may be required in the ground layer, traces in that internal layer should be minimized. A general rule of thumb is to ensure the ground plane has gaps smaller than 10 mm [2]. The ground plane should be solid across high frequency traces (Fig. 1). A ground plane area at least three times the high frequency signal trace width should be enforced on each side of the trace [3].

SHIELD/GUARD VIAS

To ensure high frequency signals are kept within their traces, placing vias around the critical traces is recommended (Fig. 2). This is technique is extremely effective for frequencies up to at least 5 GHz. A general guideline is to ensure that the distance between the vias is at most a quarter of the system’s resonant wavelength. However, it is often more effective to locate the shield vias at most a 1/10^th (or preferable a 1/20^th) apart.

In the example above, a high frequency trace originating from a wireless Microcontroller Unit (MCU) and terminating at an onboard antenna is protected.

Another important characteristic of the trace shown in Fig. 2 is its trace width, which dictates its inherent characteristic impedance. To maximize power transfer from the MCU to the antenna, the characteristic impedance needs to match the impedance of the microcontroller and antenna, which typically is 50 Ω. Determining the optimal trace width is based on the PCB composition and out of scope for this paper, but a simple calculator can be found on our website [4].

STITCH VIAS

Stitching vias are like guard vias. Stitching vias allow for greater EMI performance because various ground layers can be connected, yielding a lower parasitic series resistance to ground for all signals on the PCB (Fig. 3). The general rule for spacing should be followed as specified in the Shield/Guard Vias section. In a standard PCB design software, the size between vias (grid) as well as the via size can be selected. Below we show the control window in Altium (Fig. 4).

HIGH VOLTAGE TRANSIENTS

High voltage transients are defined as voltages several orders of magnitude larger than expected voltages (i.e., 10 kV) for a short period of time (a fraction of a second). Despite the short duration of transients, they can destroy a circuit. Static electricity from a human hand as well as USB cable removal/insertion can cause the transients. An effective safeguard is electrostatic discharge (ESD) protection, implemented as Transient Voltage Suppressors (TVS), which are special diodes. Note that using a conventional diode does not successfully protect the circuit because of their high parasitic capacitance that prevent the diode from reacting quickly enough to curb the transient; TVS have a capacitance on the order of picofarad. Applying such protections is recommended whenever a transient is expected, such as USB connectors or user buttons. There are four considerations when choosing a TV:

1. Standoff Voltage higher than normal operating voltage
2. Clamp voltage (for given peak current) is below the protected IC’s pin’s max voltage rating
3. Specified peak current exceeds expected peak current
4. Bidirectional protection is chosen (if required)

Be wary that an excellent PCB schematic alone (Fig. 5) is insufficient to protect against the transients: an effective PCB layout is an equally important step. For example, a +/- 15 kV IEC-61000-4-2 Air-Gap Discharge ESD event with a nanosecond pulse results in a pulse current of 15 A. A ½ inch PCB trace represents L = 10 nH of parasitic inductance, which translates to a clamp voltage that is 450 V¹ in additional to the diode’s clamp voltage [3]. This ineffective PCB layout would, therefore, render the ESD protection useless since most components are not rated for handling 450 V. Even if the components do not fail immediately, the product would have a lower MTBF reliability rating.

¹450V = (L*dI/dT = 10 nH * 45A/10⁹s)

BATTERY PROTECTION

Modern medical equipment commonly employs secondary rechargeable Lithium-based batteries for various reasons. Ventilators, for example, commonly employ backup power sources to mitigate power supply failure, as mandated by IEC Standard 80601-2 [5]. Other devices are fully wireless-based and, therefore, depend on a single primary rechargeable battery for connectivity applications. Even in non-safety-critical applications, medical devices are developed with adequate safety standards to minimize the risk of failures, such as fire or explosion that would endanger the user. IEC 62133 is a cross-industry standard for exporting devices with lithium batteries in accordance with international compliance. IEC 62133-2 specifies requirements and tests for the safe operation of lithium-based batteries [6]. IEC 62133-1 is applicable to nickel-based batteries.

Some of the battery tests include:

• Free fall
• Crush
• Over charging
• External short circuit

The batteries must be able to tolerate these tests with no fire or explosion results. Each battery will have a different safe voltage current, operating/charging temperature, and number of cells. Clearly, these safety standards levy requirements not only the battery manufacturer, but also the device manufacturer (battery integrator).

The Lithium-based battery should either have the protection circuit built-in or integrated onto the PCB. The choice will depend on the product’s mechanical and cost requirements. A PCB-based solution can be slightly more cost-effective in some cases but would increase the verification burden onto the application integrator. Specifically, the protection circuit must protect against:

• Overcharge
  • A 3.7 V Li-Ion battery, for example, can typically be safely charged only to a certain level, such as 4.2 V.
• Over-discharge
  • A 3.7 V Li-Ion battery must not be discharged below a certain voltage. 3 V is a common cutoff voltage for this battery class.
• Charging too quickly
  • A charge rate is typically recommended that should not be exceeded. 0.5 C or 1 C are common charge rates.
• Discharging too quickly
  • A maximum discharge current rate as a function of the battery capacity is typically specified. 2 C is a common, but not a universal, parameter value.

Exceeding any of these limits can increase the probability of critical device failure and, thereby, endanger the user. Fig. 6 shows a simplified protection circuit that could be integrated into the application PCB.

SUMMARY

Ubiquitous pitfalls exist in designing modern medical devices that are highly reliable, safe, cost-effective, and functionally competitive. As a result, a myriad of tradeoffs must be balanced to deliver a competitive product that can secure market share. We discussed tangible steps to help accomplish that vision. Any questions on this article (or any related topic) may be directed to the author.

REFERENCES

[1] Reliable Design of Medical Devices by Richard C. Fries.

[2] MAX 13202E Datasheet. https://datasheets.maximintegrated.com/en/ds/MAX13202E-MAX13208E.pdf.

[3] PCB Design and Layout Fundaments for EMC by Roger Hu.

[4] PCB Characteristic Impedance Calculator. https://simplonics.com/simulations/.

[5] IEC 80601-2 Standard.

[6] IEC 62133-2 Standard.

[7] Lithium-Ion Cell Protection Examples. https://www.digikey.com/en/maker/blogs/lithium-ion-cell-protection