One of the biggest trends in the medical device industry is miniaturization—the development of smaller, more portable devices to address the challenges of limited space in hospitals and home healthcare, enabling healthcare professionals to quickly and easily move devices from one patient to another. Ventilators, diagnostic equipment, pumps, and suction devices are all being improved to adapt to this trend. The healthcare industry, particularly in Europe and America, has made significant contributions to the miniaturization of medical devices, striving to transfer patients from hospitalization to home care as quickly as possible. In home care, portability is crucial for patients to receive care and use devices, helping them achieve the highest possible quality of life.
Miniaturization presents a challenge for medical device designers, who must not only reduce product size but also design devices capable of supporting various configurations and care settings. Consequently, sensor manufacturers are responding to this miniaturization demand by offering flexible mounting options, smaller dimensions, and integrating multiple sensor functions into a single package. In some cases, sensors are even finding applications in previously unexplored areas, such as surgical instruments.
The sensor platform offers a variety of mechanical interfaces, mounting methods, package types, and I/O options, enabling medical device designers to select the appropriate interface for their applications while reducing costs and board space. For example, pressure sensors can be integrated into a variety of designs because they offer multiple connectivity options (port styles), package types (DIP, SIP, surface mount), and output options (analog or digital).
Flexible sensor packaging options
The sensor's flexible packaging options (including manifold mounting and cable assembly options) give designers greater flexibility in placing the sensor on a printed circuit board (PCB). Furthermore, it eliminates the need for tubing and related connectors, resulting in smaller, simpler, and faster-to-assemble medical devices. The flexible mounting options also ensure that the sensor is precisely placed in the desired location, close to the patient or liquid media (such as blood, chemicals, or water), for accurate and high-precision measurements.
pressure sensor
The ability to place sensors close to the patient is crucial for many applications, such as dialysis, where accurately measuring dialysate and venous pressure is essential. Pressure sensors must be able to precisely monitor dialysate and blood pressure to ensure they remain within pre-defined ranges.
Applications of this type require sensors that are small in size and resistant to liquid media. In many cases, sensors incompatible with liquid media require additional mounting components for protection, increasing the product's size, cost, and complexity. Liquid media resistance is particularly important when monitoring patient respiration, as the sensor must be able to withstand the patient's cough and exhaled humid air.
For example, Honeywell's TruStability™ HSC/SSC board-mount pressure sensors and 26PC flow-through pressure sensors can directly contact the liquid, providing rapid feedback on dialysate pressure during patient filtration. These sensors also offer dialyzer manufacturers a variety of port options and package designs.
Image caption: Honeywell Sensing & Control's TruStability™ board-mount pressure sensors offer a range of mechanical interfaces, mounting options, and I/O options, as well as liquid media compatibility options, enabling medical device designers to select the right interface and package to reduce board space.
Sensors for wound care
Negative pressure wound therapy is another application that benefits from the miniaturization of pressure sensors. Miniaturized sensors can provide high reliability and excellent quality while minimizing product costs. Through a platform approach, medical device manufacturers can use the same basic sensor across a variety of wound care products, and designers can scale the output to meet specific application needs. For example, Honeywell's NBP series board-mount basic pressure sensors offer a range of package types, pressure ranges, housings, and port options, making them easier to integrate into medical devices while considering cost. The NBP series sensors are packaged in a 7mm x 7mm space, meeting the space requirements of portable home healthcare products.
Image caption: Honeywell's NBP series board-mount basic pressure sensors are compact and easy to place on closely spaced printed circuit boards or in small devices. A range of package types, pressure ranges, housings, gel coatings, and port options can meet the specific application needs of medical designers.
Force sensor
Force sensors are used in medical applications, such as infusion pumps, to measure pressure in drug delivery tubing. These sensors employ piezoresistive technology, are compact, and can accurately and reliably sense force (<100 ppm). Their high sensitivity to pressure changes allows for early detection of blockages and timely audible alarms to healthcare professionals, improving patient safety. The sensors are also scalable to different pressure ranges, including 0 to 1 psi (FS01) and 0 to 3 psi (FS03), and pre-validation is provided for multiple ranges, enabling greater design flexibility.
Force sensors are available in a variety of package types, allowing for various attachment methods to be mounted onto device tubing, providing maximum flexibility, especially in infusion pumps and dialysis applications. Honeywell's FSS, FSG, and FS01/FS03 series force sensors offer a variety of package types and sizes, facilitating integration into space-constrained infusion pump applications and enhancing portability, thus improving patients' quality of life. Furthermore, Honeywell's FSS and FSG force sensor product lines have added wing-shaped leads, enabling medical device manufacturers to transition from through-hole designs to surface mount designs, which is more conducive to current high-volume production.
Integrated components
Some sensors (such as temperature and humidity sensors) integrate multiple functions, which will further promote the trend of device miniaturization and offer various assembly and manufacturing advantages, including:
- Eliminating multiple sensors on the circuit board simplifies the design, manufacture, and installation of the device.
- Enhanced device functionality.
- Improved patient comfort and safety: Because the device has integrated sensors, the number of vulnerable parts and connection points is reduced, decreasing the number of potential sources of failure.
- By eliminating the circuit board outline from the PCB to the microprocessor, the design verification process is simplified.
- Reduced total cost.
The intelligent components within the sensor itself also contribute to product miniaturization. For example, fully calibrated, temperature-compensated, and amplified sensors reduce the number of components required on the PCB, helping to reduce product size, weight, and cost. Typically, these designs eliminate the need for external components such as resistors and amplifiers to compensate for and calibrate the sensor signal. Because no compensation or calibration is required, manufacturers can save time and money on testing processes, ultimately shortening product development and production cycles. For more information about Honeywell Sensing & Control, please visit http://sensing.honeywell.com or email [email protected]
Manufacturers can further eliminate external resistors, capacitors, and amplifiers by adding a sensor digital interface option. The digital interface allows sensor signals to connect directly to the microprocessor, saving board space in space-constrained medical device designs.
Image caption: Honeywell's HumidIcon™ digital temperature and humidity sensor offers two functions in a small package, enabling greater miniaturization.
For example, Honeywell's HumidIcon™ digital temperature and humidity sensor provides a temperature-compensated digital I2C output, eliminating signal conditioning components on the PCB and thus reducing board space and associated costs. This not only simplifies the integration of the sensor with the microprocessor but also eliminates the various problems associated with multiple signal conditioning components on the PCB.
The sensors are housed in an ultra-compact SOIC-8 surface-mount package and are available in two configurations: the filterless, condensation-free HIH-6130 and the HIH-6131, which features a water-blocking filter and is condensation-resistant. These sensors can operate at voltages as low as 2.3V, enabling them for low-power applications to extend battery life, which is crucial for device portability.
Platform-based sensors
Platform-based sensors offer a variety of port types, mounting options, rated voltages, and output formats (digital or analog) for diverse medical applications. This flexibility allows designers to select the appropriate sensor for their application without the need for expensive custom components, while also enabling engineers to easily modify their device designs and specifications. This combination of options typically reduces potential additional costs and accelerates time-to-market.
This platform-based approach can accommodate many of the specific requirements of medical device design, including device size and shape. The sensor platform building blocks are pre-validated for all standard options and configurations, helping to provide customers with high-quality and reliable products from the outset, while also accelerating research and development and manufacturing.
Sensor manufacturers help designers create medical devices suitable for today's healthcare environments, whether in hospitals or home care devices, where size, ease of use, portability, reliability, accuracy, and cost are paramount. In the pursuit of increasingly miniaturized devices, designers must understand the pressure type and range, accuracy, supply voltage, packaging requirements, and output type needed for their applications to select the most suitable sensor. Furthermore, they need to know the liquid media the sensor may come into contact with to select sensors compatible with these liquids. Because sensors are available in a range of sizes, packaging options, mounting options, port types, and outputs, they can be used in a wide variety of applications.
