Switch Requirements for Medical Applications
When it comes to meeting today’s requirements for medical devices and instrumentation, component manufacturers are not only faced with the customer project challenges, but also meeting FDA regulations. In the area of switch components, current trends continue to call for further miniaturization to meet the needs of space-saving applications like hearing aids. The switch design must conform to cleanliness, reliability and extended life for applications such as glucose meters and transdermal patches. The versatility of switch designs is paramount in order to be considered for use by top medical device and equipment suppliers, particularly in the rapidly growing market of personal and portable medical devices.
Image 1: As one of the smallest tactile switches available on the market, the KMT Series switch from C&K Components helps reduce the overall size of hearing aids
Miniaturization and reliability are two of the more important considerations in the medical design market today. To reduce the overall size of the medical device, each component must be designed as small as possible. For example, in behind-the-ear hearing aids, switch miniaturization is required in order to reduce the overall size of the hearing aid, thereby increasing user comfort and reducing the visibility of the device behind the ear.
Switches also play an important role in the use of personal and portable medical equipment. Many portable medical devices utilize operation switches (on/off switches) and special function switches. Portable blood pressure cuffs, for example, benefit from switch miniaturization through a reduction in the overall weight and assembly of the cuff. The blood pressure cuffs have to work on the first actuation and keep working for a high number of actuations, making reliability a paramount concern when considering a new switch design.
While miniaturizing switches is a key element in meeting top medical equipment manufacturer requirements, other switch challenges are being encountered in other applications. Glucose meters for example, require an extremely high level of reliability in order to accurately read the blood sugar level of a customer. Detect switches in glucose meters initiate the process of analyzing the blood, thereby affecting the accuracy of the reading.
Image 2: C&K’s KSU Series detect switches help provide accurate readings in glucose meters
Growing in popularity are the use of transdermal patches for the delivery of post-surgical drugs. Switches are being used in transdermal patches to trigger the dispensing of pain killers, antibiotics and other drugs through the skin. It is essential that the switch operate properly not only to ensure medication is being dispensed, but that the proper dosage is dispensed on schedule. To prevent the switch from accidentally being actuated and dispensing the drug at an improper time, self-regulating tactile switches are being designed in.
In order to increase reliability, design considerations must be taken into account for the switch to withstand exposure to moisture and humidity. For example, switches for hearing aids have to be resistant to perspiration generated behind the ear. Synthetic sweat can be extremely abrasive to hearing aids and the switch. If not designed and manufactured to withstand these specific environments, moisture may enter the hearing aid and corrode the board, resulting in failure. To prevent corrosion, devices and components can be sealed or component plating materials can be altered. When sealing is not an option due to size or other considerations, switch manufacturers turn to alternate plating schemes to combat corrosion.
In addition to reliability and considerations for alternative materials and plating, switch versatility is yet another design requirement. By offering multiple mounting and actuation configurations, customers are afforded greater functionality and ease of use. For example, side actuated miniature switches in blood pressure cuffs makes it easier to operate, increasing customer appeal for the product.
In addition to FDA regulations, each customer has different specifications and reliability requirements in terms of cleanliness, traceability, and overall design. There are continuing efforts to increase the quality level of components through traceability, for example, requiring component manufacturers to work within highly identifiable batches and specifically designed material flow processes.
Today, more miniature switches are being designed into applications that typically did not use switches at all. This is resulting in the evaluation of different materials, processes and overall switch designs in order to meet the next generation medical applications. Clean room assembly requirements in a number of markets including medical are increasing along with the demand for zero defect products. Smaller switch products with increased versatility, reliability and lifespan, improved plating materials and consistent packaging processes, are most likely to be chosen by the industry’s top medical equipment manufacturers.
Jerome Smolinski joined C&K in 2002 as Product Manager for Smart Card Connectors for the Americas. Before joining C&K, he held various positions in Product Marketing Management at Amphenol, and Project Manager for FCI. Jerome graduated from Superior School of Technology and Business in France and after his stay in the Boston area, he is now re located in C&K French factory, where he is currently working as Senior Product Manager for Tact Switches and Smart Card Connectors.