Ingestible sensors – Components and emerging technologies

Ingestible sensing capsule is one of the fast-emerging technologies today to greatly impact health, nutrition, and clinical areas.

Thanks to the significant advancements in electronics, sensors, batteries, optics, materials science, and chemistry, this noninvasive device can provide reliable information about the internal condition of your gut through images, pressure measurements, pH readings, core temperature data, and also measurement of chemical constituents inside the gut.

The unique feature of such an ingestible sensor is that its passage through the gut lumen gives them access to each gastrointestinal tract organ. The outputs from it provide invaluable information to reveal the disorders and the impact of medical supplements, food, and environmental changes on the gastrointestinal tract.

According to studies, the global smart pills, or ingestible devices, the market is expected to nearly reach the one billion dollar mark, especially focused on two primary functions of wireless patient monitoring and diagnostic imaging.

Many factors are important in the design of ingestible sensing and monitoring capsules. They include their physical dimensions, aerodynamics, and density, allowing for facile ingestion and whether they rely on passive or active locomotion. The other critical factors include high fidelity and private transmission of data to an external receiver, the lifetime of the battery, and the biocompatibility of the materials used in the capsule.

The general components and requirements of ingestible devices for reliable and durable operation are as follows:

  • Power supplies – Due to the duration of operation and the need to gather data and transmit data, ingestible devices need efficient power consumption.
  • Telecommunications – High image quality and high frame rates are the important features of ingestible sensing capsules, which require wide bandwidth communication to process and transmit large amounts of data.
  • Microcontrollers and processors – Microcontrollers and processor units are responsible for ordering the commands to and from sensors and transmitters.
  • Power switches – Magnetic reed switches are generally used for turning the ingestible devices on before their use.
  • Cladding – The claddings of ingestible electronic devices are required to be made of biocompatible materials and remain intact in the acidic environment of the gastrointestinal tract.
  • Sensors – The sensors are the core components that define the operation of the ingestible electronic capsule. They sense either physical or chemical parameters.
  • Passive and active capsule locomotion – Most of the ingestible sensing capsules rely on passive progression in the gut. However, it is also possible to remotely control the movement of the ingestible device along the GI tract.
  • Localizing the electronic capsule – Magnetic fields and antenna arrays are used to gain accurate knowledge of the position and orientation of the capsule.

Here are some of the current commercial systems and emerging technologies of ingestible sensors:

1. Imaging Capsules

Endoscopy is the largest part of the imaging capsules market. The driving factor is to find a method to replace relatively invasive endoscopies based on tube endoscopes inserted into the oral or rectal orifices. Endoscopic procedures are poorly tolerated by patients due to the rigidity of endoscopy instruments and their relatively large dimensions, restricting access to many areas of the gut. Other issues include pain, sedation issues, and the possibility of repeated screening. The first wireless capsule endoscopy incorporated a small camera, LEDs for lighting, transmitter, batteries, and microcontrollers.

In recent years, significant progress has been made in video capsule endoscopy, with signal processing and computational methods developed to improve diagnostic capabilities and accuracy when using camera capsules. Algorithms for detecting hemorrhage and lesions, reducing practitioner review time, localizing the capsule or lesion, assessing intestinal motility, improving video quality, and managing data are among them.

2. Temperature Sensing Capsules

The ingestible temperature sensors are commonly used to monitor body temperature mainly to measure heat stress in patients, workers in industrial environments, and possibly soldiers in the field. These capsules consist of a thermistor-based temperature sensor and are used for core body temperature measurements.

3. pH Monitoring System

Due to the secretion of HCl, the gastric juice inside the stomach is extremely acidic. pH monitoring systems measure the pH of the GI tract during its passive progression. The capsules usually last several days, and the test is carried out while the patients continue to follow their normal diets and activities. The pH capsules should leave the stomach in less than 5 hours, pass through the small intestine in less than 6 hours, and pass through the colon in less than 60 hours on average. The timing depends on the body characteristics, environment, degree of body hydration, and, more importantly, on the food ingested.

4. Pressure Sensing Capsules

The pressure profiles of the GI tract are obtained using pressure sensing capsules. Pressure measurements’ true values are still unknown. The pressure capsules have not given any accurate information regarding peristaltic wave propagation, and the pressure profiles remain confounding.

5. Medication Monitoring Pills

The medication ingestion monitoring pill is a more recent entrance to the market. This pill serves to remind/signal users that medicine must be taken and track the amounts consumed. The pills are passive. Upon hitting, acidic electrolytes are activated, transmitting a signal to a small, battery-powered body patch and sending the data via Bluetooth to a smartphone in the vicinity.

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