Modeling Microscopic Chemical Sensors in Capillaries

TL;DR

This paper develops detailed models of microscopic chemical sensors in capillaries, accounting for blood cell shapes and flow, to evaluate sensor detection performance and guide design.

Contribution

It introduces a realistic modeling approach of blood flow and cell shapes for microscopic sensors, comparing detailed and simplified models for performance estimation.

Findings

Average chemical absorption similar in both models

Simpler models are adequate for performance estimation

Full models are needed to analyze force and absorption variations

Abstract

Nanotechnology-based microscopic robots could provide accurate in vivo measurement of chemicals in the bloodstream for detailed biological research and as an aid to medical treatment. Quantitative performance estimates of such devices require models of how chemicals in the blood diffuse to the devices. This paper models microscopic robots and red blood cells (erythrocytes) in capillaries using realistic distorted cell shapes. The models evaluate two sensing scenarios: robots moving with the cells past a chemical source on the vessel wall, and robots attached to the wall for longer-term chemical monitoring. Using axial symmetric geometry with realistic flow speeds and diffusion coefficients, we compare detection performance with a simpler model that does not include the cells. The average chemical absorption is quantitatively similar in both models, indicating the simpler model is an adequate design guide to sensor performance in capillaries. However, determining the variation in forces and absorption as cells move requires the full model.