What are sensors?

In medicine and biotechnology, sensors are tools that detect specific biological, chemical, or physical processes and then transmit or report this data. Some sensors work outside the body while others are designed to be implanted within the body.

Some monitoring devices consist of multiple sensors that measure a number of physical or biological parameters. Other devices may be multifunctional, incorporating sensors and then delivering a drug or intervention based on the sensor data obtained. Sensors may also be components in systems that process clinical samples, such as increasingly common “lab-on-a-chip” devices.

Sensors help health care providers and patients monitor health conditions and ensure that they can make informed decisions about treatment. Sensors are also often used to monitor the safety of medicines, food, environmental conditions, and other substances we may encounter.

How are sensors used in current medical practice?

digital thermometer
Thermometers are a type of sensor commonly used in health care.

Many different types of sensors are already used in health care, including self-care at home. Thermometers translate the expansion of a fluid or bending of a metal strip in response to heat into a number corresponding to body temperature. Paper-based home pregnancy tests contain a substance that changes color in the presence of hormones indicating pregnancy. In hospitals and other provider-based settings, you can find more complex types of sensors like pulse oximeters (also known as blood-oxygen monitors), which measure changes in the body’s absorption of special types of light to provide information on a patient’s heart rate and the amount of oxygen in the blood.

How might novel sensors improve medical care or biomedical research?

Advances in technology, engineering, and materials science have opened the door for increasingly sophisticated sensors to be used in medical research. A group of NIBIB-funded researchers developed a compact, wireless, implantable brain sensor that can record and transmit brain activity data. Building on previously developed brain-computer interfaces that used wired connections, this new sensor may someday lead to unobtrusive, thought-controlled prosthetics and other assistive devices for people with amputated limbs, paralysis, or other movement impairments.

fluorescent proteins
Test tubes containing purified proteins made to fluoresce in different colors. Source: NIBIB

Researchers at NIBIB aim to improve existing sensors through a variety of means, such as making fluorescent probes easier to see and increasing the capabilities and enhancing efficiency of individual sensors.

Some scientists are exploring biological sensors, which rely on substances that occur naturally in the body, or artificial compounds that mimic natural substances, to capture molecules that are important to measure in the body. Biosensors may provide insights into disease processes that are hard to detect directly, such as dysfunctions in brain chemistry that are thought to play a role in many mental disorders.

For example, one method for studying chemical processes in real-time uses engineered cells that can be “programmed” with receptors that latch onto specific brain chemicals. The resulting chain of activity causes a protein within the cell to change color that researchers can detect with a certain type of laser microscope. The biosensors remain active in the brain for several days, allowing scientists to study changes in brain chemistry over time, which may help inform efforts to improve drug treatments for mental disorders.

While many advanced sensors aren’t practical for routine medical care, they allow researchers to study the basic foundations of disease in more detail than previously possible, and to develop new technologies that could dramatically improve the quality of life of people with severe disabilities.

What technologies are NIBIB-funded researchers developing with sensors?

Sensors play key roles in all aspects of health care—prevention, diagnosis, disease monitoring, treatment monitoring—and the range of research involving sensors is equally broad. In addition to health-related applications, NIBIB funds studies to test new materials and technologies for building sensors, to develop new sensors that can advance medical research, and to promote healthy independent living through home-based and wearable sensors.

New Materials & Technologies

Good health requires not only protecting our bodies but safeguarding things we put into our bodies as well. NIBIB-funded researchers developed a sensor using a thin membrane made from of a special kind of plastic. The researchers loaded the membrane with a compound that creates a voltage difference across the membrane in the presence of OSCS, a potentially deadly contaminant sometimes found in preparations of the commonly used blood thinner heparin. OSCS is inherently highly charged and interacts with the compound-loaded membrane without the need to apply an external electrical current. By measuring the voltage, scientists can quickly identify OSCS-contaminated samples before the heparin is administered to a patient. The reaction between OSCS and the membrane is also reversible, so the sensors can be used repeatedly.

a worker sterilizes equipment in an isolator
A quality control analyst sterilizes equipment in an isolator.​​
Source: Sanofi / Eric Larrayadieu (Interlinks Image), via Flickr CC-BY-NC-ND 2.0

Another NIBIB grant supported research to develop an instrument to detect and monitor levels of vapor phase hydrogen peroxide (VPHP). VPHP is much stronger than the type of hydrogen peroxide commonly used in first aid care but has a similar use: to disinfect and sterilize pharmaceutical manufacturing equipment and facilities. After sterilization procedures, manufacturers have to ensure VPHP levels are reduced back to a minimum to protect workers and product quality. The researchers developed a sensor that uses a new type of highly efficient and extremely sensitive laser to continuously monitor VPHP levels throughout the sterilization process. The sensor can also detect how much VPHP has been absorbed by packaging and other materials within the facility, such as sterile isolators or other protective barriers.

Advancing Medical Research

Many illnesses develop and progress as a result of faulty regulation or dysfunction of a range of hormones, neurotransmitters, or other important body chemicals. Tracking such chemical activity is key to unraveling disease processes, but current sensors are generally limited in the number of chemicals that can be analyzed at one time or require those chemicals to be labeled first, thus greatly increasing the time, cost, and complexity of sensing. NIBIB-funded researchers seek to improve on biosensors in a variety of ways, such as creating novel types of coatings that improve sensor sensitivity, selectivity, and stability; and developing a fluorescence-based strategy for detecting proteins in living organisms and in real time.

Healthy Independent Living

Environmental and mobile sensors are already a part of many people’s everyday lives. For example, faucets that automatically start when you place your hands under them and shut off when you’re done washing. Lights that turn themselves on when you enter a room. Wearable bands that track your daily activity, perhaps even coordinating with your smartphone to allow you to track data over time or share your information with others. NIBIB supports initiatives to develop improved sensor and related information technologies for home and mobile use that will sustain wellness and facilitate coordinated management of chronic diseases. For example, one research team is working to improve the ability of “smart homes” to make sense of real-time sensor data and to recognize changes in a resident’s activity patterns that may signal changes in well-being, such as a fall or disrupted meal schedule.

smart home illustration
Illustration of a "smart home" showing some types of environmental sensors that can be useful for daily life. Source: Diane Cook, Washington State University

What are important areas for future research on sensors?

The types of sensors being developed and studied currently may play key roles in expanding and greatly changing the delivery of health care. One area in particular that may benefit from sensor research is point-of-care (POC) technologies.

Point-of-care refers to the place where patients receive health care, which may be anywhere from primary care offices or community clinics to emergency rooms or even patients’ own homes. POC research seeks to address barriers to health care that have arisen from the concentration of services in highly specialized medical centers and labs. POC technologies may allow providers to diagnose and treat a particular health condition in a single visit, so patients don’t need to make additional appointments or wait for test results.

Besides funding studies seeking to improve the manufacturing process for low-cost POC technologies, NIBIB-funded efforts are already underway to develop cost-effective POC solutions for detecting a range of medical conditions, including H5N1 influenza and allergies and other autoimmune diseases. Miniature, implantable sensors could continuously monitor a person’s health status, providing more accurate information than conventional disease screening and a clearer sense of when a doctor’s visit is needed. Integrating compact, wireless sensing technologies into medical devices or chronic treatments like long-term oxygen therapy may help lower treatment costs and be easier for patients to use. Such technologies may also be compatible with mobile devices, allowing for remote monitoring and assessments in real-time.

Some of the challenges to sensor research include simplifying and automating the preparation of patient samples to be used at the point-of-care and overcoming the body’s natural rejection response to implantable or minimally invasive sensors.

Reviewed October 2016