Description
The problem. Cybergenetics promises real-time, personalised optimisation of therapies for noncommunicable diseases by closing the loop between measurement and control in living systems. Translation is stalled by a hardware gap: there is no in vitro platform for real-time, multi-input multi-output (MIMO) control of mammalian microenvironments. Many optimisation strategies run open-loop [1], and prevailing microfluidic devices cannot impose multiple, time-varying biochemical inputs needed to separate treatment effects from spontaneous disease dynamics [2].
Our solution. We present a modular microfluidic platform for MIMO cybergenetic control composed of a signal-generation device (“Pharmacist”) coupled to a cell-culture device (“Nurse”). The Pharmacist is a multilayer PDMS chip with 12 inlets partitioned into four hydraulically isolated modules implementing: (i) healthy, (ii) pathological, (iii) healthy + treatment, and (iv) pathological + treatment. Normally-open membrane valves and on-chip peristaltic micropumps provide programmable dosing, while integrated staggered herringbone mixers (SHMs) rapidly homogenise selected inputs prior to delivery. The Nurse is a mechanically clamped PDMS culture module built from interchangeable parts: a 300 µm-thick PDMS stencil containing forty 700 µm-diameter chambers and a flow layer with four parallel perfusion channels (ten chambers each). A reconfigurable two-step workflow enables precise seeding via a removable Chamber Extender for manual pipetting or acoustic droplet ejection (ADE); after overnight adhesion, the Extender is replaced with the flow layer and connected to the Pharmacist via capillaries.
Results. We characterised all twelve peristaltic micropumps and identified a linear dosing regime (0–2 Hz) with minimal intra-pair variability, delivering up to ~2 µL·min⁻¹ per pump. SHM geometry was optimised in COMSOL for rapid mixing and validated experimentally, achieving a mixing index ≥ 0.95 within ~10 mm downstream at a total flow of 10 µL·min⁻¹. We demonstrate complex, time-varying multi-chemical waveform generation by independently modulating the concentration of two fluorescent tracers (Cy5 and fluorescein), overcoming a common limitation of valve-based platforms where coupled peristaltic actuation restricts independent control of final media composition [3–5]. Finite element analysis predicts that, at an inlet flow of 10 µL·min⁻¹ and chamber depths of 100–500 µm, media exchange occurs in 9–17 min while maintaining shear stress below 0.5 dyn·cm⁻². Experimentally, the clamped interface remained leak-tight under 10 psi for 24 h with no cross-channel contamination, and static seeding at 10⁶ cells·mL⁻¹ yielded well-spread adherent cells.
Conclusions. By combining independently addressable dosing, rapid on-chip mixing, and modular, leak-tight culture, the Pharmacist–Nurse platform enables programmable, time-varying MIMO microenvironments for closed-loop control of mammalian systems. Our work supports real-time control of signalling and drug response, benchmarking of control algorithms, and systematic studies that decouple treatment efficacy from disease progression.
REFERENCES
[1] Lee, Bai-Yu, et al., Nature Communications 8.1 (2017): 14183.
[2] Mustafa, Adil, et al., Biosensors 15.7 (2025): 427.
[3] Schuster, Brooke, et al., Nature Communications 11.1 (2020): 5271.
[4] Gómez-Sjöberg, Rafael, et al., Analytical Chemistry 79.22 (2007): 8557–8563.
[5] Zhang, Ce, et al., Science Advances 5.4 (2019): eaav7959.