Smart Optical Sensors Drive Medical Device Portability

Smaller. Smarter. More reliable. The same technology innovations that enable intelligent handheld devices in the consumer market are also enabling more portable medical equipment—both in hospitals and for in-home use. Today’s healthcare devices must be highly integrated and efficient, as they are at times used by minimally or untrained people under less than optimum conditions. Sensors and connectivity are now key elements in meeting these needs, enabling healthcare anywhere via the Internet of Things (IoT). Reliability is a primary consideration, as these are the diagnostic and treatment tools serving a global population with increasing healthcare needs and expectations.
 
On the healthcare landscape, connected devices are essentially creating networks of highly instrumented devices, the impact of which truly remains to be seen. We do recognize, however, that much of their utility relies on implementing one or more sensors to spot changes in diverse, real world environments and turn them into electrical signals that can be measured and acted upon. Healthcare situations demand accurate readings—facilitated by sensors that are highly integrated, small, robust, stable over the long term, and draw little power. This unique combination of performance and features is critical in advancing connected health devices, enabling both portability and adaptability, as sensing capabilities required of devices in the field will likely evolve over time.
 
Optical Sensors Offer Versatility and Performance
The optical sensor is one of the most versatile tools in these circumstances as it can look at objects (such as products on a manufacturing line), through media (such as liquids flowing through tubes), or at reflections off things (such as surfaces that have been processed in some way). However, obtaining the kind of accurate, repeatable measurements that make analysis meaningful can be difficult. For example, as anyone who has fitted a screen protector to their phone can attest, an increasing number of materials with low reflectance has become available. Several are being dispatched into service in medical devices, such as in the windows through which sensors detect bubbles or contamination in flowing liquids. Making sense of the resultant signals calls for a sensor with programmable sensitivity levels and output to cope with varying levels of reflectance and low-contrast scenarios.
 
Sensor signals can often be quite ‘delicate,’ meaning they are often small currents or voltages measured in electrically noisy conditions from sensing devices that change performance with environmental factors such as ambient light or temperature, and over their operational lifetime. LED performance inside the sensor is subject to aging as light output in LEDs degrade gradually over time.
 
Optical Sensors Address Medical Application Demands
In the medical device arena, portable medical equipment can be the most problematic in terms of design requirements. The sensor must offer low power consumption to reduce overall system power and increase battery life. It must also integrate as much functionality in as small a footprint as possible. One example of such a device is TT Electronics’ Photologic V OPB9000 reflective optical sensor, which has been specifically designed for medical applications. This optical sensor includes a fully integrated analog front end, on chip processing, and digital interface in a surface mount package measuring just 4.0mm by 2.2mm by 1.5mm—space savings of as much as 80% in circuit complexity. Greater integration solves many industry challenges—turning a standalone sensor into a low-power sensing module that includes all its supporting circuitry and has programmable sensitivity and thresholds. Inherent flexibility enables these kinds of devices to serve many markets in a more cost-effective fashion than their discrete alternatives.
 
Used in hospital, lab, and portable equipment, this type of optimized sensor can detect media and cartridge presence, as well as contamination and fluid levels. With market-leading ambient light immunity of 25klux, it can be used where other optical sensors cannot. It also integrates a wide range of features not found in other devices, such as self-calibration and Automatic Gain Control, temperature compensation circuitry, programmable contrast sensitivity, and an industry standard communication interface. With a response time of just 6μs, it is extremely fast—without the use of microcontrollers and outputs, which results in significant cost savings. While mass produced, these sensors can be programmed to the specific application, presenting additional cost savings and enabling first to market customization capabilities.
 
Connected Medicine Reveals the Need for Adaptability
Designing medical equipment that promotes next-level care requires flexibility that is readily enabled by smarter sensing technology. Dynamically adaptable optical sensing can be used in hospital, lab, and portable equipment to detect media and cartridge presence, as well as contamination and fluid level detection. Fuelled by the proliferation of connected devices, as well as the IoT and the concept of global connectivity, every medical device component used must deliver a level of quality, reliability, and capability that surpasses the demands of almost any other sector.
 
Consider the need to maintain a sterile environment, a common challenge to developers of medical equipment and made more complicated by close patient contact requirements. In a home care setting, sensors have to reduce patient risk by supporting self-diagnosis—for example a home-based blood dialysis machine must correctly and consistently detect the presence of cartridges and waste products such as blood and other fluids. Optical devices are ideal in addressing this risk, measuring and sensing a range of conditions without physical contact. The sensor consumes minimal power and is highly integrated, small, and able to withstand a tough environment—all key characteristics that improve equipment portability.
Small and portable with robust performance, adaptable sensors are making it possible to quickly deliver smart, cost-effective solutions that enable data-driven care.

This is part two of our adaptable sensor series, digging deeper into portability enabled by these powerful devices. Read part one here. Read part three here.
 

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Sergey Komarov is a field applications engineer specializing in opto-electronics in sensors applications. Komarov has over 20 years of industry experience in technology development and product engineering at TT Electronics, AB Elektronik GmbH, Optek, Cadence Design Systems, Texas Instruments, and National Semiconductor. He holds degrees in physics, materials engineering, and an MBA in industrial management. His passion is to research and pursue new opportunities in opto-electronics sensing technologies, innovative designs, and applications.