People of ACM - Nivedita Arora

August 6, 2024

Will you tell us how you define the concept “sustainable computational materials”? Why is the promotion of sustainable computational materials so important for the computing field and the larger society?

 The UN report “Halfway to 2030” highlighted data scarcity as the hindrance to actionable insights for UN Sustainable Development Targets, such as desertification, climate change, agriculture, and urban green spaces. Collecting real-time, granular environmental data is essential for urban health and disaster prevention. However, it must be done sustainably with minimal environmental impact in terms of e-waste or disturbance to biodiversity. This is where my research of “sustainable computational materials” comes in. Envision agricultural sensors that self-generate power from electrically active microbial communities in the soil to wirelessly communicate water content, pH, and forest fire activity for ecological health monitoring. Imagine a sticky paper note that can sense urban heat islands yet can be thrown away in the recycling bin at the end of its life. Picture a computational face mask that measures health biomarkers, is powered by human breath, and can quickly disintegrate into recyclable parts. At its core, the vision for sustainable computational materials research re-envisions the computing stack from a sustainability-first approach for its entire life cycle: (1) Manufacturing: using eco-friendly, biodegradable materials and sustainable manufacturing processes; (2) Operation: designing and operating battery-free systems; and (3) Disposal: ensuring responsible end-of-life disposal or reuse.

What was the greatest challenge in developing your PhD Dissertation project “Sustainable Interactive Wireless Stickers”?

Building the first example of “sustainable computational materials,” the interactive wireless stickers, entailed rethinking the design parameters of embedded computing systems to include “sustainability” and “materiality.” This quickly revealed a critical roadblock: the lack of traditional off-the-shelf components or microcontrollers that satisfy the system requirements for energy efficiency, eco-friendliness, cost, or form factor. Thus, the greatest challenge as a systems researcher (but also the most enjoyable part), was to dive down one level below in the computing stack and start thinking from the devices, materials, and fabrication perspective. This required adopting an interdisciplinary mindset and working at the intersection of chemistry, materials science, mechanical engineering, computer science, and industrial design, disregarding traditional boundaries between different scientific fields. Such an approach enabled me to create thin, flexible, paper-like, low-power devices for audio sensing, wireless communication, and display. Together as a system, these devices become an interactive sticky note which can be placed on any object and operate by harvesting power from light and human touch.

In the specialized area of batteryless devices, what innovations have propelled this field? Would you like to make a prediction about the near future of battery-less devices?

Empowered by Moore’s law, the era from the 1980s to the 2000s focused on making devices which consume less and less power. The next decade pushed for battery-less devices powered by energy harvesters. From 2010 to the 2020s, two techniques emerged that made battery-less devices more practical and scalable. First, ambient backscatter communication, which offloads the most power-hungry task in an IoT device—generating high-frequency radio waves for wireless communication—to the infrastructure. Second, intermittent computing, which arose from the realization that power harvesters are severely affected by environmental factors, necessitating computer architecture that supports complete power-off and subsequent recovery of the last state.

There is a recent understanding among systems researchers that making devices sustainable requires more than just removing batteries. Sustainability goes beyond energy; there is a need to address the issue of rising e-waste. In the next decade, I predict the rise of what I call ‘life-aware computing,’ where IoT devices will be both battery-less and biodegradable, and computing tasks will adapt to the device's age. That is the future that the Sustainable Computing Lab I direct at Northwestern University is building.

In addition to demonstrating the technical feasibility of sustainable computational materials, what societal perceptions will need to change for these technologies to be widely adopted?

We are accustomed to the transient nature of the natural world; for example, a tree changes with the seasons, growing and shedding leaves. However, we view technology as static and often adopt an extractive, use-and-throw mindset. Imagine, instead of today’s clunky smart home voice control devices, having a real living plant that performs the same functionalities. How will humans' relationship with such a plant-powered device change? As the research field of sustainable computational materials advances, human and societal perceptions will evolve to consider objects and infrastructure around them as living, interacting, and ageing beings that change their functionality over time.