Josep Miquel Jornet

The terahertz (THz) band and the optical frequency window are emerging as powerful enablers of next generation biomedical technologies, supporting high resolution sensing of biological processes, targeted intra-body actuation, and intra-body communication for coordinated functional operation. Although each modality has demonstrated significant promise individually, research efforts have largely progressed in isolation, limiting the exploration of their potential for integrated deployment. This comprehensive survey bridges these domains by presenting a unified analysis of THz and optical modalities for intra-body sensing, actuation, and communication. Building on this foundation, we articulate a vision for intra-body systems in which multiple functions are seamlessly coordinated at cellular and subcellular scales. Applications such as continuous health monitoring and closed loop therapeutic interventions illustrate the transformative potential of these integrated approaches. We outline a three-stage roadmap covering foundational modeling, in-vitro integration, and in-vivo translation, identifying critical open challenges including compact source generation, power delivery, biosensing miniaturization, and biocompatibility.

The upper region of the frequency spectrum approaching the THz band has become the topic of interest due to its multi-GHz bandwidth availability. The majority of research has been focused towards establishing meaningful communication links by expanding on today's electronics, innovative waveform and wavefront design at the physical layer, and signal processing strategies for ultrabroadband signals. With major progress being made on that front, the upper networking layers remain a big challenge yet to be solved. In this paper, a new medium access channel (MAC) protocol is proposed that leverages reflective surfaces with different orientations and tilt angles to create an illusion of omnidirectional connectivity. The network performance is analyzed through the use of an analytical and simulated model, leveraging an in-house developed network simulator. The proposed protocol shows improvements in latency and overall throughput by over 100 Gbps for the lowest antenna beamwidth that allows for stronger non line-of-sight (NLoS) links. Similarily, the proposed protocol minimizes the vulnerabilities of traditional MAC solutions currently being investigated such as blockages, and timing delays.

In this work, we report a dual-mode ferroelectrically programmable on-chip antenna. The antenna is built on a silicon wafer using complementary metal-oxide semiconductor (CMOS) processes and exhibits two programmable resonant modes: one in the super high frequency (SHF) range and one in the extremely high frequency (EHF) range. The SHF mode resonates at 8.5 GHz and exhibits ultrawideband (UWB) behavior, while the EHF mode resonates at 36.6 GHz. Both resonance frequencies can be tuned in a non-volatile fashion by controlling the ferroelectric polarization state of a Hafnium Zirconium Oxide (HZO) varactor monolithically integrated into the feed line. This programmability arises from the ferroelectric switching of the embedded HZO film, which results in a non-volatile variation of its permittivity upon application of a voltage pulse. Ferroelectric switching occurs at approximately ±3 V and induces maximum resonance frequency shifts of 381 MHz for the SHF mode and 3 GHz for the EHF mode, corresponding to fractional frequency changes of 4.5% and 8.3%, respectively. Unlike previously reported ferroelectrically tunable antennas, our reported antenna combines full integration, CMOS compatibility, higher operating frequency, compact footprint, and non-volatile programmability.

In this paper, the optimal wavefronts for maximum ratio transmission (MRT) are investigated under path blockage effects in the near-field region. To characterize the behavior of the optimal wavefronts, a new deterministic channel model is proposed in the presence of obstacles, which describes blockage effects by the variation of the electric field based on the uniform theory of diffraction (UTD). With the proposed channel model, the linear precoder designs are formulated as optimization problems to maximize the power density at the desired point under fully digital and analog array assumptions, where the amplitude and phase distributions of the solutions characterize the optimal wavefronts to achieve MRT. The optimal precoders reveal that the proposed channel modeling must be required to optimize near-field communications systems in the presence of obstacles, which, together with electromagnetic wave simulations, confirm that linear precoding with the proposed channel model achieves MRT under any blockage effect, and the optimal wavefront varies for each blockage situation.

In this paper, we develop a tractable analytical framework for a three-dimensional (3D) indoor terahertz (THz) communication system to theoretically assess the impact of the pointing error on its coverage performance. Specifically, we model the locations of access points (APs) using a Poisson point process, human blockages as random cylinder processes, and wall blockages through a Boolean straight line process. A pointing error refers to beamforming gain and direction mismatch between the transmitter and receiver. We characterize it based on the inaccuracy of location estimate. We then analyze the impact of this pointing error on the received signal power and derive a tractable expression for the coverage probability, incorporating the multi-cluster fluctuating two-ray distribution to accurately model small-scale fading in THz communications. Aided by simulation results, we corroborate our analysis and demonstrate that the pointing error has a pronounced impact on the coverage probability. Specifically, we find that merely increasing the antenna array size is insufficient to improve the coverage probability and mitigate the detrimental impact of the pointing error, highlighting the necessity of advanced estimation techniques in THz communication systems.