Miniaturised Sensor Array Collects Ischemic Data in Real-time
Professor Josep Samitier
In the 1960s TV series Star Trek, Dr McCoy externally scanned his patients with a small device making detailed diagnoses within seconds. While McCoy’s medical tricorder remains fiction, researchers have developed miniaturised sensors that provide real-time information to physicians during endoscopic procedures. The low-cost and mass producible sensor array has many potential applications in minimally invasive surgical procedures, as well as detailed diagnoses using information collected during the procedure.
Investigator Professor Josep Samitier of the Institute for Bioengineering of Catalonia (IBEC), Barcelona, Spain reports that the idea for the tiny sensor array came through collaboration with a team that had developed a new robotic system for minimally invasive surgery.
The research team used a natural orifice transluminal endoscopic surgery (NOTES) approach via the intestine to reach the stomach. Explored for almost a decade in vivo, some researchers believe that NOTES could be the next paradigm shift in surgical approaches. NOTES advantages include no external abdominal scar, lower anaesthesia use, swifter recovery, and shorter hospital stays. However, as the procedures depend upon computer assisted imaging, complete monitoring of the procedure can be complex. Also the use of a flexible endoscope in NOTES can be challenging for some surgeons due to difficulties in depth of perception and spatial orientation.
Samitier said, “One of the problems is how to get information in real-time to the surgeons so they can make decisions. We looked at how to introduce the endoscopic system into the body, where to cut and remove some of the tissue. Ischemia is a concern.” The team’s solid-state, potentiometric sensors identify ischemia occurrence after gastrointestinal and gastroesophagael anastomosis, monitoring pH and potassium. To provide useful data, the device needed to be able to collect many signals, therefore many sensors would be necessary. Professor Samitier explains, “In principal, it would be more or less easy to detect ischemia in tissue, but the problem is how to do that when you need to reduce the size of the sensor system so it can be introduced via the endoscopic device and analyse different parameters in real-time.”
WE CAN BUILD A SPECIFIC SYSTEM TO INCLUDE THREE, FOUR, FIVE TIPS IN THE SENSORS, SO IN THIS CASE THE TOTAL SIZE OF THE SENSOR IS AROUND THREE OR FOUR MILLIMETRES IN DIAMETER.Professor Josep Samitier
The team successfully miniaturised sensors, as well as optimised them for the harsh acidic conditions of the stomach. “At the moment, each sensor has a diameter of less than one millimetre, so they are very small. We can build a specific system to include three, four, five tips in the sensors, so in this case the total size of the sensor is around three or four millimetres in diameter,” Samitier says. He expects in the future, using nanotechnology, the size may be reduced even further.
Despite the tiny size, the sensors can provide a wealth of information. The array has been tested in porcine models measuring ischemia when blood flow to the stomach is clamped. Results show that both ischemia and reperfusion states can be sensed and tissue damage information can be collected. By detecting local ischemia resulting from poor anastomotic perfusion, surgeons can address the issue and possibly prevent anastomotic leakage or failure. In addition to monitoring during the procedure, data can be analysed post-op. “You can record the signals or visualise them on a computer monitor and there can be an alarm to assist in the process. It can work for many hours, so during the surgery and after the surgery for analysis,” he explains.
Looking forward, the team hopes the device can be employed in human trials before too long. Samitier says, “At the moment, we are working on developing a model to be used in human trials. It could be possible in five years.”
Professor Samitier also is very optimistic that the sensor array could have other applications utilising the NOTES approach. He suggests, “It would be possible to use the system to detect other ions or biomarkers within the framework of minimally invasive surgery.” Considering current innovations in nanotechnology and parallel developments in the miniaturisation of surgical tools, Samitier believes there are exciting times ahead. Samitier says, “It’s clear that all these elements will help in the next ten, twenty years the evolution and improvement of surgical techniques.” While McCoy’s medical tricorder may remain as fiction, “scarless” surgery aided by miniaturised sensor arrays could soon be a reality.
In vivo ischemia monitoring array for endoscopic surgery. (2014) Available here: http://www.sciencedirect.com/science/article/pii/S0956566314001705
NOTES – the next surgical revolution? (2007)