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Low-cost Microfluidic Testbed for Molecular Communications with Integrated Hydrodynamic Gating and Screen-printed Sensors

Maide Miray Albay, Eren Akyol, Fariborz Mirlou, Levent Beker, Murat Kuscu

TL;DR

This work addresses the high cost and limited customizability of experimental molecular communications (MC) testbeds by introducing a microfluidic MC platform that is inexpensive (~$1 per unit) and rapidly prototyped (<1 hour). It couples a hydrodynamic gating transmitter with a screen-printed polyaniline-based pH sensor receiver, enabling end-to-end MC experiments and reconfigurable channel architectures suitable for IoBNT scenarios. The paper demonstrates programmable amplitude and pulse-width control, along with a 4-ary CSK end-to-end demonstration, including ISI scenarios, illustrating the platform's versatility and potential to accelerate MC research and deployment. By leveraging common lab equipment and on-demand sensor functionalization, this testbed lowers barriers to exploring MC concepts in practical healthcare and IoBNT applications.

Abstract

Molecular Communications (MC), transferring information via chemical signals, holds promise for transformative healthcare applications within the Internet of Bio-Nano Things (IoBNT) framework. Despite promising advances toward practical MC systems, progress has been constrained by experimental testbeds that are costly, difficult to customize, and require labor-intensive fabrication. Here, we address these challenges by introducing a low-cost ($\sim$\$1 per unit), rapidly fabricated ($<$1 hour), and highly customizable microfluidic testbed that integrates hydrodynamic gating and screen-printed potentiometric sensors. This platform enables precise spatiotemporal control over chemical signals and supports reconfigurable channel architectures along with on-demand sensor functionalization. As a proof of concept, we demonstrate a pH-based MC system combining a polyaniline (PANI)-functionalized sensor for real-time signal detection with a programmable hydrodynamic gating architecture, patterned in a double-sided adhesive tape, as the transmitter. By dynamically mixing phosphate-buffered saline (PBS) with an acidic solution (pH 3), the testbed reliably generates pH-encoded pulses. Experimental results confirm robust control over pulse amplitude and pulse width, enabling the simulation of end-to-end MC scenarios with 4-ary concentration shift keying (CSK) modulation. By combining affordability and rapid prototyping without compromising customizability, this platform is poised to accelerate the translation of MC concepts into practical IoBNT applications.

Low-cost Microfluidic Testbed for Molecular Communications with Integrated Hydrodynamic Gating and Screen-printed Sensors

TL;DR

This work addresses the high cost and limited customizability of experimental molecular communications (MC) testbeds by introducing a microfluidic MC platform that is inexpensive (~$1 per unit) and rapidly prototyped (<1 hour). It couples a hydrodynamic gating transmitter with a screen-printed polyaniline-based pH sensor receiver, enabling end-to-end MC experiments and reconfigurable channel architectures suitable for IoBNT scenarios. The paper demonstrates programmable amplitude and pulse-width control, along with a 4-ary CSK end-to-end demonstration, including ISI scenarios, illustrating the platform's versatility and potential to accelerate MC research and deployment. By leveraging common lab equipment and on-demand sensor functionalization, this testbed lowers barriers to exploring MC concepts in practical healthcare and IoBNT applications.

Abstract

Molecular Communications (MC), transferring information via chemical signals, holds promise for transformative healthcare applications within the Internet of Bio-Nano Things (IoBNT) framework. Despite promising advances toward practical MC systems, progress has been constrained by experimental testbeds that are costly, difficult to customize, and require labor-intensive fabrication. Here, we address these challenges by introducing a low-cost (\<$1 hour), and highly customizable microfluidic testbed that integrates hydrodynamic gating and screen-printed potentiometric sensors. This platform enables precise spatiotemporal control over chemical signals and supports reconfigurable channel architectures along with on-demand sensor functionalization. As a proof of concept, we demonstrate a pH-based MC system combining a polyaniline (PANI)-functionalized sensor for real-time signal detection with a programmable hydrodynamic gating architecture, patterned in a double-sided adhesive tape, as the transmitter. By dynamically mixing phosphate-buffered saline (PBS) with an acidic solution (pH 3), the testbed reliably generates pH-encoded pulses. Experimental results confirm robust control over pulse amplitude and pulse width, enabling the simulation of end-to-end MC scenarios with 4-ary concentration shift keying (CSK) modulation. By combining affordability and rapid prototyping without compromising customizability, this platform is poised to accelerate the translation of MC concepts into practical IoBNT applications.

Paper Structure

This paper contains 12 sections, 5 figures.

Table of Contents

  1. Introduction
  2. Materials and Methods
  3. Sensor Preparation
  4. Potentiometric Readout Circuit
  5. Preparation of Microfluidic Chip with Hydrodynamic Gating Architecture and Device Integration
  6. Results
  7. Amplitude Modulation
  8. Pulse Shaping
  9. Pulse Width Characterization
  10. Pulse Amplitude Characterization
  11. Communication Experiments
  12. Conclusion

Figures (5)

  • Figure 1: (a) Fabrication flow of the microfluidic chip: i) Fabrication of screen-printed electrodes. ii) Fabrication of hydrodynamic gating pattern on double sided tape. iii) Fabrication of inlet and outlet on the PMMA. (b) Continuous monitoring of pH changes and data acquisition using a BLE-integrated custom-developed circuit board. (c) Exploded view of microfluidic chip. (d) Close-up schematic view of the hydrodynamic gating-based transmitter architecture. (e) Schematic view of screen-printed pH sensor. (f) Experimental setup. (g) Real image of microfluidic channel. (h) Pulse generation with hydrodynamic gating transmitter. (i) Dimensions of the screen-printed sensor.
  • Figure 2: (a) Cylic voltammetry of PANI deposition on fabricated pH sensor. (b) Calibration curves of pH sensors.
  • Figure 3: Hydrodynamic gating-based transmitter design with zigzag mixing structure. L1= 9.2 mm, L2= 80.5 mm, w= 100 $\mu$m, s= 400 $\mu$m.
  • Figure 4: Receiver response as a function of the flow rate ratio between pH 3 and PBS solutions corresponding to different pH levels for amplitude modulation.
  • Figure 5: (a) Receiver responses to four modulation levels ($Q_1/Q_2 = 0.5/5$, $2/5$, $5/5$, and $7/5$) and thresholds ($T_1 = 6.30\,\mathrm{mV}$, $T_2 = 16.14\,\mathrm{mV}$, and $T_3 = 24.15\,\mathrm{mV}$), with $T_\mathrm{g}$ held constant at 20 s. (b) Pulse width characterization for different $T_\mathrm{g}$ ranging between 90 s and 2 s, with $Q_1/Q_2 = 0.5/5$. (c) Receiver response to a randomly generated sequence of 20 symbols without ISI, $T_\mathrm{g} = 10\,\mathrm{s}, T_\text{pi} = 20\,\mathrm{s}$. (d) Receiver response to a randomly generated sequence of 20 symbols under ISI effects, $T_\mathrm{g} = 3\,\mathrm{s}, T_\text{pi} = 10\,\mathrm{s}$.