Fig. 5: Automated dynamic control of enzyme activity.

a Custom electrochemical platform with a patterned ITO glass slide attached to a 3D-printed housing. b An interdigitated electrode is generated through laser-cutting the ITO-coated glass into a zig-zag pattern to ensure the generated peroxide (on the bare electrode) is at the vicinity of the HRP/gelatin hydrogel for detection. c Working mechanism of the electro-biochemical platform. Horseradish peroxidase (HRP)-conjugated gelatin is pre-deposited on working electrode 2 (WE2). Working electrode 1 (WE1) consists of a bare ITO electrode and is tasked with generating peroxide by applying a reducing voltage (−0.8 V). In-gel HRP (WE2) then catalyzes the generated peroxide, and the resulting electron cycles with Fc that is present in the solution above. A current (from the cycling of Fc) can be read when an oxidizing voltage is applied (0 V vs Ag/AgCl). d Demonstration of data writing and storage. (i) Generated charge on WE1 (navy) and current obtained from WE2 (pink) were plotted over time. Pink filled circles: endpoint current recorded at 120 s. (ii) Voltages applied on WE1 and WE2 over time. e Demonstration of ‘long-term’ data storage. (i) Total charge applied on WE1 for 600 s. (ii) The following currents obtained on WE2 (inset: 0–120 s). Red line and open circles indicate when the endpoint current was recorded (at 120 s). Blue: first round (#1) of data writing (600 s) and recording (~3000 s). Green: second round (#2) of data writing (600 s) and recording (3600 s), conducted immediately after the first round.