Exact spatial molecule capture improves communication under flow
Exact Cap Response and Aperture Selection for Molecular Communication under Aligned Drift
Information TheoryEmerging Technologies
Summary
Molecular communication is a way to send information using tiny molecules that travel through fluid. The authors study how to best catch these molecules on a small receiver surface when there’s a flow pushing them in one direction. They find the exact mathematical relationship between the size of the receiver’s catching area and the timing of molecule arrivals, improving how well signals can be separated from noise. This helps decide the best size of the receiver’s catching area depending on flow speed to get the clearest message.
What this means in practice
- •For nanotechnology engineers: Design nanoscale communication devices that optimize molecule capture areas under fluid flow for clearer signal reception.
- •For synthetic biologists: Improve synthetic cell communication by selecting optimal receptor sizes in response to fluid flow conditions.
Authors
Yen-Chi Lee, Chun-An Yang, Nan Yang
Abstract
Spatial reception under directed molecule transport requires balancing useful molecule capture against intersymbol interference (ISI). To characterize this balance, we study a fully absorbing spherical receiver that counts absorption events only within a prescribed cap. Using the known joint first-hitting law under aligned drift, we derive exact cap impulse, cumulative, and eventual responses. We perform stable cumulative evaluation. We then assess the derived responses through particle simulations and time-step comparisons, and demonstrate that our conditional-timing analysis explains when opposite drifts of equal magnitude can favor the same wider aperture. We also show that for the studied geometry and a symbol duration of $0.15$ s, the aperture that maximizes the signal-to-interference difference (SID) increases from $29.13^\circ$ at zero drift to $61.86^\circ$ at a drift magnitude of $40$ $μ$m/s. These results (i) connect joint arrival-time and location statistics to spatial reception design, (ii) characterize the tradeoff between useful molecule capture and ISI, (iii) support SID-based aperture selection for a given drift and symbol duration, and (iv) quantify the SID loss incurred by retaining the zero-drift optimal aperture for the same symbol duration.