Low-frequency antenna arrays enable obstacle-penetrating communications, but their large physical footprint—a 4 × 4 array at 150 MHz requires 16 m2—prevents practical deployment. DeformRF enables portable, deformable arrays that compress to backpack-size yet maintain beamforming performance when deployed on flexible substrates. Our key insight is that data-driven methods can predict complex electromagnetic behavior under deformation without real-time simulations. DeformRF combines: (1) a 260,000-sample synthetic dataset mapping deformations to EM characteristics, (2) physics-inspired ML models achieving >94% prediction accuracy on average, and (3) smartphone-based 3D reconstruction requiring no infrastructure. In real-world experiments, DeformRF maintains beamforming gains within 1 dB of optimal despite severe deformation, while baselines degrade by 4–10 dB. For emergency response scenarios, our 4 × 4 flexible array achieves ±5° direction-finding accuracy when tracking signals through buildings, enabling practical indoor deployment of large low-frequency arrays.

Mechanochromic films are micro-structured reflective surfaces that usually shift color from red to green to blue depending on the amount of deformation. While prior research has focused on the fabrication of these films, their potential in HCI remains underexplored. This paper introduces a design space for mechanochromic interfaces that change colors in response to deformation, such as pushing, pulling, shrinking, and stretching. Our contribution includes fabricating the mechanochromic film in multiple variations: substrate color (transparent, non-transparent), substrate form (flat, textured), and mechanochromic film pattern (single-tone, partially patterned by masking method or chemical etching method). We propose mechanochromic interfaces that integrate variations in materiality with variations in actuation mechanisms to produce visual feedback during interaction. Technical evaluations characterize material capabilities, and application scenarios illustrate use in real-world contexts.

Recent trends in flexible antennas and printed circuit boards present an opportunity to leverage deformable substrates such as textiles to deploy large UHF, VHF and ISM band antenna arrays in smart homes. Low-frequency large antenna arrays are rarely deployed in indoor settings due to their large size which makes them bulky and difficult to deploy. By embedding these arrays on existing surfaces such as curtains, we can improve through-wall sensing, beamforming for IoT devices equipped with low-power radios and indoor localization of Bluetooth tags.

A long-standing challenge in radios for wearables is to design ultra-low power, yet high performance receivers with good sensitivity and spectral efficiency while being compatible with WiFi. The vanilla envelope detector used in standard UHF RFID is the most popular receivers on backscatter tags since they are passive but suffer from poor sensitivity and cannot decode complex modulations, which makes them a poor choice for directly decoding data from WiFi packets.

Advances in flexible conductive substrates such as conductive wallpaper and paint present new opportunities for optimizing the performance of IoT nodes in smart homes and buildings. In this paper, we explore an unconventional use of such substrates for pulling frequencies of oscillators across IoT devices and wireless front-ends connected to the substrate. We show that by using this technique, we can replace precise crystal oscillators by lower precision and lower cost ceramic oscillators without compromising their ability to be used for tasks that require precise frequencies such as frequency-synchronized multi-static backscatter and synchronized sampling. We present an end-to-end design including a) analysis of conditions under which frequency pulling of oscillators across conductive substrates can work, b) a new technique to detect frequency locking across oscillators without requiring explicit communication, and c) an adaptive method that can be used to synchronize oscillators at minimum power consumption. We then show that these elements can be composed to design a high-performance multi-static backscatter system that performs as well as one that uses a shared high-precision clock but at an order of magnitude less monetary cost. We show that our system can scale and operate at very low power, while having low complexity since it requires no explicit interaction among devices attached to the substrate.