The increased miniaturization of health-based electronic sensors potentially allows myriad monitoring instruments to be embedded in a single device. Among recent developments, consumer smart rings now host a number of sophisticated analytical tools, reflecting a compromise between cost and functionality (Figure 1). These typically include photoplethysmography/pulse shape measurement, temperature, and motion/inertial measurement unit sensors. There are also numerous prototype sensors in development that have shown promise for custom analyte detection, which might be incorporated into ring architectures including galvanic monitors [14], nano-tattoo–based circuits [15], and custom analytic cells [16]. For powering these devices, there is the potential to extend duty cycles through the use of solar cell technology and a wide range of emerging options for wireless data transmission from such devices. Although the commercial focus lies in the development of these products for the direct-to-consumer market, an attractive proposition could be to deploy a standardized version for use at scale in global health. This would require that data and device standards be identified, and a minimum set of sensors and functionality be established for patient monitoring. This could, for example, reflect current aggregated health care needs of national priority (eg, cardiovascular monitoring) or sensors fine tuned for regional needs including epidemic, pandemic, or episodic flares of specific diseases where tracking is important.

In terms of connectivity, various options exist for wireless-based communication between the device and a data hub/host. The most straightforward of these is via a Bluetooth link to a nearby smartphone, with the option to bounce data directly to the cloud (Figure 2). In regions where 4G and 5G networks are available, this could utilize direct-to-cloud connectivity through 802.11 Wi-Fi protocols on local area networks (2.4 GHz band). However, on the global scale where network infrastructure is limited, this might capitalize on low-power area networks (LoRaWAN), which have been proven successful in a number of nations, allowing data to be transmitted in defined packets at intervals [17]. Yet another option could be through connection to the new low-orbit satellite–based networks being developed such as Star Link or the Inmarsat system [18]. In theory, a multitude of options could be made available, with the possibility of a standardized smart ring capable of communicating with a data hub anywhere in the world at any time. Data collected or stored would be ideally linked to databases formatted for electronic health records to allow passive, real-time longitudinal monitoring of people affiliated with country-specific health systems, or patients as they show progress as engaged users of the health system. Examples of such monitoring could include the monitoring of vital signs, providing emergency alerts to health providers (and tied to global system for mobile communication (GSM) location–based tracking for emergency responders), and monitoring of mobility (eg, during a pandemic crisis). Clearly, any approach of this nature would require compliance with health data privacy architectures including provisions regulated by bodies such as HIPAA (Health Insurance Portability and Accountability Act), GDPR (General Data Protection Regulation), and the World Health Organization but the benefits could justify such a challenge [19].

The ultimate goal of developing a standardized, commoditized, affordable smart ring product capable of wireless communication across the globe presents a Herculean challenge. However, if introduced according to the above tenets, this could realistically have a marked beneficial impact on global health. As such, it may be attractive to one or more of the emerging cadre of billionaire philanthropists who have demonstrated their capacity to address societal health needs. One could envision the initial development costs being ultimately offset by sponsor nation states, who stand to achieve savings in health care costs while they elevate the standard of care of their citizens [20]. Another potential for revenue funding and also incentivizing subjects to embrace smart ring technology could be the tokenization of personal data for financial gain. Leaving aside the ethical considerations, it is conceivable that trial sponsors or epidemiologists would have interest in the monitoring of data from a large segment of the population for a fixed period of time. This is the basis of compensation for participants in traditional clinical trials, but the scale of the smart ring network globally could offer a quantum leap in opportunities. Such opportunities would need to be carefully structured to adhere to ethical guidelines, but the tactic of sale of personal data is already established in the consumer world, and this could offer a compensatory mechanism that some participants could presumably embrace [21]. Of course, in projecting associated costs globally, it will be important to assess the total economic burden of ownership, which will include device, supply chain, lifecycle updates, and the impact of e-waste. Although future-leaning, the reality of such a device eventually being realized is potentially high. Sensor, wireless, and power technologies are all advancing rapidly, and the key human variable for ring adherence (ie, finger diameter) is relatively narrow (typically 14‐23 mm).

In order for the envisioned device to be realized, a number of technical challenges will need to be overcome with regard to device engineering.

Although a multitude of obstacles need to be addressed, there is evident potential for the deployment of smart ring technologies in long-term health monitoring. In terms of the pathways for development, each of the potential use cases envisioned presents unique challenges and opportunities and the ethical, legal, and data privacy burdens for each are expected to reflect scale and intended use (Figure 3). Nonetheless, given striking advances in health technology, computational and communication networks, and health literacy, it seems inevitable that such frameworks will evolve naturally. In order to propel such opportunities forward, we advocate enhanced dialog between the technology community, health advocacy groups, global health organizations, and philanthropic leaders. We encourage readers of this journal to jump start and advance this dialog as members of the citizen science community, as the impact is potentially significant. Given the evident potential for such a device to play a transformative role in health care reform, we believe this call-to-arms for the device engineering community is timely and warranted and look forward to active dialog to progress this vision.