The electronics that you swallow, encapsulated in a pill, will sit in your gastrointestinal tract for a short time, before being ejected from your body like regular food waste. During this time it can capture videos, release drugs, monitor heart rate and respiration, and perform other such tasks.
Proteus Digital Health was one of the pioneers in ingestible tech, and their technology is now used commercially by close to ten health systems. Their solution comprises a pill, a patch that is attached outside to the side of the stomach, and a mobile app/desktop portal. The pill is made of whatever drugs are required, and fitted with a sensor made of natural, ingestible materials like copper, magnesium and silicon. When a patient swallows the pill, it dissolves like a normal pill in the stomach but leaves behind a sensor, which is activated by fluids in the body. This sensor sends a signal to the patch, which also measures heart rate, body position and time of medication detection. This information is sent to the patient’s or doctor’s mobile phone.
Regular drug intake is very important for those undergoing complex medical treatments such as organ transplants. This pill could be very useful for such patients. Proteus has teamed up with Tokyo-based firm Otsuka to embed Proteus’ sensors into Abilify—a drug used for serious mental illnesses.
Another forerunner in the space is Israel-based Given Imaging. Their PillCam series comprises pills with ingestible cameras, which can help doctors to view different parts of the patient’s digestive system like the oesophagus or colon. It is a painless alternative to tests like endoscopy and colonoscopy. The PillCam Colon, for instance, uses a battery-powered camera to take high-speed photos as it slowly goes down the intestinal tract over a time period of eight hours. The images are transmitted to a recording device worn around the patient’s waist and later reviewed by a doctor. Although the images are not as sharp as those obtained through normal colonoscopy, it is a viable alternative for those who cannot bear the pain or feel embarrassed by the procedure.
Other versions of PillCam help doctors to see the small intestine and oesophagus. The company has also developed SmartPill—an ingestible capsule that measures pressure, pH and temperature as it travels through the gastrointestinal tract. This helps doctors to assess GI motility.
Bravo pH is another capsule-based test that helps to test for acid reflux. The miniature pH capsule attaches to the oesophagus and sends pH data wirelessly to a small recorder worn on a shoulder strap or waistband. Information is collected over multiple days, enabling doctors to study the frequency and duration of acid flowing back up into the oesophagus. This helps to confirm the presence of gastroesophageal reflux disease (GERD). This is a totally catheter-free solution, so the patients can go about normal activities and have a normal diet while the pill unobtrusively monitors their acid reflux. They can remove the receiver to take a shower. This type of monitoring under a normal routine gives better results than keeping the patient under observation.
Unique engineering challenges
The most obvious challenge to edible electronics is, obviously, miniaturisation. It is impossible to implant or consume something that is bulky. With the electronics industry in general moving towards miniaturisation in everything, this goal has become more achievable in implantable devices, too. Unlike the traditional pacemaker, the newer leadless pacemakers are about the size of a large capsule, and can be placed directly in the heart. These can be implanted through a femoral vein puncture in about half an hour. No more bulges or scars, these pacemakers are very unobtrusive and apparently also less prone to infections. The National Heart Centre Singapore (NHCS) began implanting such pacemakers last year.
Thermal management is another huge challenge in implantable devices. Like any other electronic device, implantable devices too vent out waste heat. However, this heat should not harm the surrounding tissues. So while designing an implantable device, engineers have to consider thermal properties of biomaterials, the effect of blood flow on temperature distribution, interfacial contact resistance, effect of temperature change on various types of tissues and communication duty cycles of embedded electronic components.
Further, the in-vivo electronic device must be biocompatible—it must not cause any adverse reaction inside the body. It must be stable over time, despite the temperature and pH variations in the human body. The biocompatible materials must not contain cancer-causing toxins, and must mostly be made of materials naturally suitable to the human body. The insulation materials must match the texture and smoothness of the surface they interface with, be it tissue, bone or skin.