Sensors Today and 50 Years from Now

Introduction and History

From the bulky, stand-alone monitors installed only on the select few high-value assets, to the miniaturized gyroscopes, barometers, and compasses in smartphones, sensors have come a long way quickly. An integral part of Industry 4.0, sensors reside in the Internet of Things (IoT) like cell phones, electronic appliances, and other connected devices, measuring, collecting, and exchanging data on temperature, light, motion, location, and vital signs with other sensors in the network. As the cost of sensor fabrication, data storage, and network infrastructure decrease, 300 billion sensors are projected to be used in lifestyle enhancements in a $10.5-billion market in 2020. A higher proportion of the sensors will be printed and flexible, reaching $7.3 billion in market cap.

Sensors Applications Today

In addition to consumer electronics, sensors are used in many sectors, including agriculture, smart city, health care, military, aerospace, and energy. Sensors installed in housing facilities and on animals help farmers monitor animal welfare to minimize illness and mortality as well as increase productivity and fertility. Sensors installed in the fields inform farmers on weather and soil conditions, so that farmers can identify the best time to plant, water, fertilize, and harvest the crops.

In the smart city, sensors help city planners figure out where to install solar panels and how many, how to reduce traffic congestion, and track potential disease outbreaks. In the home, sensors can help caretakers monitor seniors with neurodegenerative disorders like dementia or Alzheimer’s, and coordinate care with the doctors and other service agencies.

In health care, sensors are crucial in helping hospitals reduce cost and at the same time maintain the quality of care. Since the Affordable Care Act has shifted from reimbursing procedures to reimbursing positive patient outcome, hospitals need to help patients—especially ones with chronic conditions like diabetes, hypertension, chronic obstructive pulmonary disease—manage their medication and lifestyle, reducing the frequency of costly emergency admissions and hospitalization.

Wireless sensors are only suitable for the continuous monitoring of glucose levels in diabetic patients, but also great for ensuring patient compliance. Patients no-show is a big problem. With telemetry, doctors can monitor a patient’s heart rate, blood oxygen levels, and even EKG remotely, so that they can get a more granular and holistic view of the patient’s condition instead of a mere snapshot. In addition, wireless sensors can be embedded into pills to monitor if and how the patients are taking their medications. However, the pill sensors are still in their nascent stage and not yet widely used.

In the military, aerospace, and energy sector, sensors are crucial in enabling predictive maintenance of equipment that demands zero-failure. With sensors, instead of reacting to potential maintenance issues, engineers can analyze the data gathered from the sensors to identify assets that require service early, in turn minimizing the cost of downtime.

50 Years from Now

Fifty years from now, sensors are likely to be smaller, cheaper, more accurate, more flexible, more power-efficient, greener, able to collect a larger variety of data, and integrated with an increasing number of different technologies.

Smaller and Cheaper

Using new platforms, manufacturers can make smaller sensors that are as high-performing as millimeter- and microwave-scale components and as cost-effective as semiconductors. The new platforms will also reduce the cost of design, development, and manufacturing. Moreover, smaller sensors are cheaper to make because they need less silicon.

Also, sensors that can self-calibrate will be cost-effective in the long run. Calibration to ensure accuracy is time-consuming. Self-calibration sensors require less maintenance and will therefore cost less. In addition, sensors that can repair themselves (self-heal) in the event of a disaster or other structural disruptions will be cheaper to use and maintain.

Higher Accuracy

The research on multi-channel cooperative spectrum sensing is still in the early stage, but it will one day be translated into multi-channel spectral sensors that are more accurate than single-channel sensors.

Sensors that are more accurate, reliable, and replicable have a better chance to obtain government regulatory approval and be used as medical devices.

More Flexible

In the future, the flexible light sensors, flexible pH sensors, flexible ion sensors, and flexible biosensors, which are still in early development, may have many applications, such as in artificial skin, wearable sensors, and micromotion sensing.

An example of a flexible sensor is the sensor for passive measuring. Based on microwire technology and magnetic fields, the sensors are thin and elastic like human hair, require no power supply, and can measure temperature, pressure, pull, stress, torsion, and position without contact.

Sensing More and Collecting More

Sensors of the future will be more effective in mimicking human senses and detect, dissect, and analyze complex signals, such as biohazards, smells, material stresses, pathogens, and corrosion. For example, instead of being able to sense a large quantity of a single analyte, such as carbon dioxide, these advanced sensors can decipher each of the components in an odor. In addition, smart dust, which are microscopic sensors powered by vibrations, can monitor diverse situations such as war zones, high-rise buildings or clogged arteries.

More Medical Applications

Right now, health-related sensors mainly have applications in the entertainment and lifestyle sectors because their capabilities are not yet considered medical-grade. In the future, more sensors will undergo the rigorous process of regulatory approval and have medical applications.

Emerging technologies in biological hazard sensing include the miniaturization of lab systems such as microfluidics, scientific validation of wearable sensors that make them medical grade devices instead of lifestyle and entertainment devices, analysis of multiple analytes on the same instrument, reduction of the size of sample required, and detection from other bodily fluids like sweat and tears.

An example of miniaturization of lab systems is an ingestible pill-sized camera that allows physicians to visualize the human intestinal tract. This procedure does not require sedation of the patient and is less invasive than the traditional endoscopy.

An example of sensing other bodily fluids than blood is a sweat sensor patch to monitor glucose levels in diabetic patients. The patch is currently in a pilot program to track the hydration levels in professional football players. If the sweat-based continuous glucose monitoring sensors are used, they will be smaller, less invasive, and easier to wear than the current blood-based CGM sensors.

Lastly, micro-sensor implants can also help track the healing of internal injuries, so that health care professionals can take appropriate actions based on continual data from the sensor.

More Energy-Efficient

Most of the existing sensors are not energy-efficient because they are always on. To make the sensors more energy-efficient, engineers can make them event-driven. This way, the sensors turn on only when an event activates them; when they are in stand-by mode, they consume close to zero power.

Sensors can also become energy-efficient by harvesting energy from their environments, such as kinetic motion, pressure, light, or the heat difference between a patient’s body and the surrounding air.

Greener

Environmentally friendly or biodegradable sensors are likely to gain more popularity in the future. For example, a green sensor may use a dissolvable paper-based battery powered by bacteria. These sensors are suitable for time-based data collection in the agricultural setting (to monitor moisture and nutrient content in the soil), in the environmental setting, or for temporary medical purposes.

Increasing Complexity and Incorporating Other Technologies

Sensors will gain additional complexity by working in coordination. Sensor swarms coordinate their activities, deciding what and where to measure through a self-learning system.

Sensors will also become more diverse as they incorporate different technologies. For example, a laser-based sensor works by firing a laser into a strip of titanium dioxide, forming an evanescent field above the sensor’s surface and identifying the analyte components from their respective unique spectrum produced in Raman scattering. Time-of-flight sensors scatter infrared light pulses to measure the distance between two objects. Piezoelectric sensors—made from materials like crystals, certain ceramics, bone, DNA or proteins—generate an electric charge in response to applied mechanical stress such as pressure or latent heat. They require no battery and can work as ultrasonic transceivers inside the body during imaging or health monitoring. Lastly, DNA printing technology will enable the fixation of DNA onto the surface of a sensor.

Conclusions