Wireless In-body Sensor and Actuator Networks

The WINNOW project aimed to explore the best ways to design communication devices that use ultra-low power for transmitting data within the human body. The focus was on creating a network of sensors and actuators implanted deeply inside the body and investigating radio and molecular communication as potential means of data transfer. The main goal was to enable short-range communication (1mm–5cm) between these implanted devices and long-range communication (5-25 cm) from these devices to a gateway node (another device) under the skin for external communication and reprogramming. The selected approach involved deploying two pacemaker devices – one in the right atrium and one in the right ventricle of the heart. These devices shared information about the amplitude and timing of the sensed signals for each heartbeat. By collectively analyzing this data, the devices could decide whether or not to deliver a pacing signal (achieved by injecting a current with specific voltage and duration). Several innovative aspects of intra-body communication systems were explored, presented and tested at Rikshospitalet, Oslo University Hospital. These include a baseband impulse system for intra-body communications, an extended range antenna system for deep implant coverage, a battery-free communication technique for wireless capsule endoscopy using a backscatter concept, and a dual-chamber backscatter communication system for cardiac pacemakers. Additionally, novel communication methods such as magnetostrictive-elastomer antennas, magnetoelectric antennas, subthreshold cardiac signaling, and zero-power schemes like Pacing Times Modulation (PTM) were proposed and studied for their potential in multi-nodal pacemaker networks. The research performed during the WINNOW project also established a theoretical framework for quantifying communication between cardiomyocytes based on extracellular vesicle exchange. The findings and results demonstrate promising advancements for improving medical implant communication efficiency and reducing power consumption.

The research conducted in WINNOW holds implications in various fields, particularly in the realization of novel implantable miniature devices and extracellular vesicle research. The demonstrated operation of the backscatter system with spaced antennas is an achievement, yet the potential for impactful outcomes lies in overcoming the challenges associated with system size reduction and integration with a subcutaneous can. The precise design of implant antennas is crucial for maintaining high efficiency and low coupling, requiring advanced electronic system design and integration. Additionally, addressing the complexities of system integration in a metallic can and accounting for signal variations due to heartbeats in the receiver design process are pivotal steps. In addition, the manufacturing challenges of magnetostrictive-elastomer antennas necessitate the development of specific procedures for successful implementation. This points to a novel research direction. Research on extracellular vesicles has led the WINNOW project group into collaborations with prominent national and international research partners in the field. The membership in the Norwegian Society of Extracellular Vesicles has been established to further foster connections with relevant experts. A notable collaboration has been also established with Stanford University, focusing on the use of extracellular vesicles as vehicles for delivering biotherapeutics to specific heart cells, including those within ischemic scar tissue. This partnership represents a step towards translating WINNOW-based research results into practical applications.

The demand for medical devices increases at a pace of 6% yearly across the globe. In the developed world this is driven by an ageing, increasingly care-demanding population, while in the developing world improved economic conditions makes use of medical devices economically feasible. Access to mobile phones and Internet has made remote monitoring of medical conditions feasible. Improved battery and communication technology makes it possible to diagnose and manage disease processes remotely enabling large scale introduction of mobile health applications. The medical device industry is an important growth business, dominated by the US. While it is a strong wish in Norway to strengthen research and development in this field, one of the serious deficiencies is the lack of biomedical engineering educational program that combines in depth understanding of the clinical and commercial aspects of wireless in-body medical device development. The current technical challenges in this field are deep implantation, large bandwidth to support large data rate or trade bandwidth for power, and small size (in mm) and weight (less than 60g). The purpose of this wireless in-body sensor and actuator networks (WINNOW) project is to develop a program that focuses on two very specific research areas of radio and molecular communication technologies. While exposing the PhD and Postdoc candidates to the clinical environments that would clinically utilize the scientific inventions, we believe that the patients benefit from getting accurate diagnosis and follow up in their normal environments with less hospitalization and cost. In addition, the project includes Oslo University Hospital to provide the fellows with the opportunity to work "bedside" with medical doctors to fully realize the scope of their engineering projects. This will give their research programs a new dimension allowing the candidates double supervision from engineering and clinical faculty.