EVADE - Electroceutical Vehicle for Antimicrobial Delivery

Closing the Circle: Targeted Phage Delivery to the Gut

Our project as a whole aims to predict and engineer phages with custom receptor-binding proteins to selectively target antibiotic-resistant (ABR) bacteria. Yet, as the project progressed, we identified a critical gap in the phage therapy pipeline: how can we effectively deliver these tailored therapies to patients resistant to antibiotic treatments?

Discussions with experts in the field indicated that phage delivery, especially to regions deep inside the body, is a pervasive issue in the phage therapy space. They emphasized that phages are most effective when delivered directly to the site of infection in the body. Thus, our team decided to develop a solution to target the epicenter of antibiotic-resistance genes - the gastrointestinal (GI) tract. To achieve this, we engineered a smart ingestible, electroceutical (electrical-pharmaceutical) capsule to deliver our phage therapy directly to the infection site in the GI tract. Our device represents an improvement on traditional enteric capsules, microencapsulation, and rectal delivery techniques by adding site-specificity and personalization to the developing field of targeted phage therapy.

We prototyped several iterations of our capsule, each representing a significant improvement on the previous design, and validated the performance of the device by developing a gastrointestinal simulation model (GSM). The GSM simulated the change in metabolites generated by bacteria, allowing accurate testing of our onboard sensing and release mechanisms, and giving us feedback on how to improve the device in subsequent iterations.

How does EVADE work?

The EVADE journey begins in our lab, where we predict and synthesize AI-modified phages to target a specific strain of ABR bacteria. Once tested and validated, the phage therapy is loaded inside of our enterically-coated capsule and given to the patient.

The capsule is then swallowed into the stomach, where a proprietary enteric coating protects the interior capsule from the acidic pH environment (Fig. 2-1). Once the pill exits the stomach, the neutral pH of the duodenum dissolves the coating, exposing the sensing mechanism of the device (Fig. 2-2). The sensor is protected by a waterproof membrane that is permeable to hydrogen gas (H₂), a metabolite of harmful bacteria found in the gut. The capsule then continually monitors the H₂ concentration in the lumen of the gut, travelling through the small intestine through natural peristaltic contractions. The sensor signals are also wirelessly transmitted to a nearby computer for further analysis.

An H₂ concentration that is significantly above the normal range is indicative of an overgrowth of bacteria, which, in the case of gut infections, can be assumed to be the target pathogenic strain. When the capsule detects this condition, a current is passed through an electromagnet, repelling a weak second magnet attached to the cap of the device. The cap is then pushed away from the main capsule, releasing the phage therapy from inside the pill (Fig. 2-3), and wirelessly alerting the user that the therapy has been delivered. A unidirectional valve prevents reengagement between the two magnets, eliminating the risk of damage to the surrounding tissues. The capsule can then safely pass through the remainder of the GI tract, continuing to transmit data until it is excreted.

The Missing Link: A Smart Pill to Overcome Antibiotic Resistance

Antibiotic resistance arises not only in hospitals but also in the broader environment, where reservoirs of antibiotic resistance genes (ARGs) drive the spread of resistant infections. In particular, the gut is a key reservoir of these genes due to its extremely high bacterial density. In both humans and animals, higher ARG levels in the gut correlate with increased pathogen density, and livestock in particular are major contributors^[1],^[2]. Over half of all antibiotics used in agriculture are often unregulated, generating vast ARG reservoirs in animal GI tracts that can spill over into the environment^[3]. Targeting the gut resistome – one of the most critical sources of resistance genes – is therefore key to controlling the rise of ABR. As such, we envision EVADE as an exploratory preventative strategy against ARG enrichment and spread, generalizable to both humans and animals. By delivering phages and adjuvants directly to one of the most important reservoirs of resistance genes, EVADE strikes at the foundation of antibiotic resistance across human, animal, and environmental health.

EVADE combines AI-modified phages with the emerging field of smart ingestible devices, which use biosensors for condition-specific drug release^[4]. Advances in electronic drug delivery have improved precision and biocompatibility^[5], making them an ideal platform for targeted phage therapy to ARG hotspots. EVADE bypasses stomach acidity with an enteric coating and conditionally releases its payload in response to intestinal H₂, a metabolite of bacterial fermentation and infection. This ensures that phages (and potentially adjuvants such as quorum-sensing inhibitors or biofilm disruptors) are delivered directly at infection hotspots and sites of ARG enrichment. By concentrating therapies locally at a high multiplicity of infection (MOI) at these sites, EVADE can efficiently clear infections or problematic bacterial pathogens. Stakeholder interviews suggest that targeted phage therapy is particularly useful for fighting infections in less accessible regions of the gut, such as the distal ileum or colon – these regions represent key target sites for EVADE

Device Operation and Technical Details

Our device has two main functions - sense the H₂ concentration inside of the gut, and release the phage therapy contained inside when a bacterial infection is detected. Each of these functions has a dedicated system inside the capsule, which is documented below.

Sensing

We utilize an off-the-shelf H₂ sensor for higher accessibility and reproducibility. The H₂ sensor outputs a small current proportional to the H₂ concentration present. A small printed circuit board (PCB) amplifies this signal to create a measurable voltage drop across a resistor, which can be read by a microcontroller unit (MCU). To prevent intestinal chyme from entering the membrane of the sensor, a polydimethylsiloxane (PDMS) coating is applied to a small opening in the capsule. This coating allows diffusion of H₂ due to its very low molecular weight, but prevents any fluids from entering the interior capsule.

The ‘DceL Extended Range Hydrogen Sensor’, manufactured by DD Scientific, was chosen to monitor the high levels of H₂ that are found inside of the GI tract. A custom PCB was designed to save as much space as possible inside of the capsule for the phage therapy. The ‘Seeed Studio XIAO ESP32C3’ MCU was chosen due to its small footprint and wireless data transmission capabilities.

Drug Release

The drug release mechanism uses a responsive electromagnet to control the opening of the pill, allowing for near-instant phage release in the GI tract. The mechanism consists of a metal-coated electromagnet in the electronics compartment and a circular neodymium permanent magnet embedded in the detachable lid.

During transit, the permanent magnet is magnetically attracted to the metal casing of the electromagnet and holds the lid shut. Once the sensing module detects a target bacterial infection, the electromagnet is powered with a burst of current, generating a magnetic field that repels the permanent magnet, pushing away the detachable lid from the main capsule body. Once the lid is detached, protrusions on the lip of the cap then prevent the lid from sliding back in place once the electromagnet is turned off.

A small battery is used to provide current to magnetize the electromagnet when drug release is required, and to power the sensing module (including the MCU). All electronics for both the sensing and drug release module are sealed inside of a waterproof, 3D printed capsule designed in CAD software. Mechanical elements, such as the detachable lid and supports for internal components, are also designed and 3D printed in house.

The ‘E-flite 70mAh 1S 3.7V 14C LiPo Battery’ was chosen to supply the high amount of current required by the electromagnet to repel the permanent magnet, as well as the large capacity in a small footprint. The ‘Uxcel 10N Electromagnet’ and ‘Min Ci Neodymium Magnets’ were chosen in tandem to ensure a high attraction between the cap and main capsule body prior to drug release, and to exert a strong magnetic repelling force between each other when drug release is required.

A complete bill of materials and cost estimate for the device is found below. All prices are listed in CAD as of October 8th, 2025. It should be noted that the CAD parts and PCB are not included, as these are custom-designed components. All CAD models can be printed on standard FDM printers, and the cost is negligible (only a small amount of filament used). The cost of the PCB is dependent on region and manufacturing speed, but is estimated to cost approximately $10.00 per board. The CAD models and PCB file can be found in the 2025 Team Toronto GitLab.

Table 1: Bill of Materials for EVADE

Device Total = $392.63 (including approximate PCB cost)

It should be noted that the vast majority of the cost of the capsule comes from the off-the-shelf H₂ sensor. We are continuing to work towards fabricating our own H₂ sensor in house, which would reduce the cost of the device by over 85%.

A build guide to assemble the device with the electromagnet can be accessed as a pdf here:

Additional Capsule Designs - Iterative Design Process

During the design process, we considered many options to release the phage therapy on demand. Our first idea was based on a published work using a nichrome wire heating element to control drug release through a fusible PCL thread mechanism. The system consisted of a nichrome wire coil, a tensile PCL filament that restrained the release mechanism, a PDMS spring and elastic band that stored mechanical energy, and a 3.7 V Li-Po battery that supplied power.

The operation of the device begins with the PCL thread intact, securing the spring and preventing drug release. When the pill detects target conditions, an electrical current is supplied to the nichrome wire, which rapidly heats due to the nichrome’s high innate resistivity. This heat melts the PCL thread (melting point ~60 °C), releasing the stored tension from the PDMS and elastic band and triggering the opening of the drug compartment for phage delivery.

However, we decided that the electromagnet release mechanism described earlier would be easier to prototype and retain the phage cargo over a longer period of time (since the force between the electromagnet and permanent magnet does not decrease over time, unlike the tension in the PCL thread).

Thus, we began the iterative design process, starting with a simple sketch, and moving towards a CAD model with the internal electronics placed inside. We frequently ran into problems during testing, requiring redesigns of the release mechanism, component placement, and even the size of the capsule, with the end goal of shrinking the capsule as much as possible. Some of these earlier designs are showcased in Figure 6 below.

Due to limitations in manufacturing equipment available to our team, the final version of the capsule described in this page is not small enough to be swallowed. Yet, we believe with additional iteration, specifically in the design of a custom H₂ sensor, we can create a capsule in the near future that can be utilized as a therapeutic device for patients.

Planned GI Tract Simulation Protocols

As the pill is ingested and travels through the GI, it undergoes a sequence of interactions between the pill, bacteria, and H₂. These three components form a negative feedback loop.

The system is evaluated against three major benchmarks:

• Pill robustness → survives waterproofing test
• Sensor reliability → H₂ readings are consistent and accurate
• Controlled release → release occurs as expected in simulated conditions
• Biological validation → phage viability is improved compared to unsheltered controls

To achieve this, we validate each of the three core components. These are the pill, bacteria, and H₂, and their interactions within the feedback loop.

1. H₂ ⇄ Bacteria

In this experiment, E. coli is to be grown under simulated duodenum, jejunum, and ileum conditions using apple sauce medium adjusted with enzymes and pH modifiers. The cultures were maintained anaerobically and incubated at 37 °C. H₂ production was measured using an MQ-8 sensor every 15 minutes.

2. Bacteria ⇄ H₂ ⇄ Pill

This combined test simulated the pill’s journey through the GI using a sequential beaker model representing the duodenum, jejunum, and ileum. The capsule is to be dropped into each compartment in order, and bacterial growth is to be tracked alongside phage release.

Exact details surrounding the protocols are broken down in the next sections.

Pill Robustness

Transit time through the GI tract ranges from 10 to 73 hrs, depending on diet and metabolism^[6]. In order to verify the preservation of our electronics and components within the pill during this time, we test the complete waterproofing of our pill shell design using cobalt chloride paper and a water bath. Cobalt chloride paper is blue when dry and turns pink when moist — which is an indicator of water penetration.

The waterproofing test will be conducted with the pill shell in two states: the full, unreleased state and the half-shell state post phage release. Ideally, 4 tests will be done for both states to ensure consistent and reliable water proofing.

The entire protocol can be accessed in the PDF embed below:

Sensor Reliability: Hydrogen Sensor Testing Protocols

The objective of the H₂ sensor testing is to establish a baseline calibration level and sensitivity to H₂ concentration of the sensor.

H₂ can be sourced from chemical suppliers at university department labs, but these come in high-pressure gas cylinders and require compressed gas safety training, safety regulator and check-valve in addition to smaller pressurized gas cylinders for lab usage.

The method of H₂ production we propose is generated by the reaction of acid with pure metals such as aluminum, zinc, or magnesium. Hydrochloric acid and sulfuric acid are both commonly used acids for this purpose.

In these metals to remove the passivating oxide coating it may be necessary to rough up the surface with sandpaper or other abrasive measures.

The total amount of H₂ produced can be calculated by a simple stoichiometric calculation with the ideal gas equation.

It should be noted that in most synthesis methods, the partial pressure of water vapour will be mixed into the H₂ and this volume should be accounted for, especially if the hydrogen is stored for a prolonged period above vapour.

There are a variety of methods to collect the produced H₂. Possible glassware solutions are listed below:

A. Inverted test tube/graduated cylinder B. Sealed vessel with syringe C. Kipp’s Apparatus

The exact lab protocols are listed in the below PDF:

Controlled Release

The pill releases phage contents at set H₂ levels. Testing occurs at various pH levels with controlled H₂ production, validating accurate sensing and timely release.

The exact lab protocols are listed in the PDF embedded below:

Biological Validation

Phage spotting will be conducted to verify that phage viability is indeed improved from a standard phage therapy oral dosage. The pill will rest, unopened, for several hours under a predetermined set of simulated extreme intestinal conditions. Then, hydrogen will be released into the solution to trigger the release of the phage lysate and standard phage spotting protocols will be used to determine the viability of the phages.

For the control, the phage lysate will rest for several hours in the simulated extreme conditions of the intestines (pH and enzyme factors). Then, bacterial solution containing a simulated “excess” of bacteria will be released into the phage lysate-GIgi tract solution. Finally, standard phage spotting protocols will be used to determine the viability of the phages.

Experimental Safety

General Safety Precautions and Mitigation Procedures

Hydrogen is lighter than air and diffuses rapidly (3.8x faster than natural gas). Hydrogen is odorless, colorless, and tasteless. Hydrogen will tend to rise quickly if released (note that in a confined space, it should diffuse into an ideal mixture of gas). Hydrogen has a flammability limit in air of 4% - 74% v/v, explosion limit of 18.3-59.0 v/v, ignition energy of 20 kJ, flame temperature of 2045 °C, and stoichiometric mixture in air of 29.6% (based on 20.9% volume of oxygen in atmosphere, which becomes (100.0% - 29.6%) * (20.9%) = 14.7%.

Experiments that produce hydrogen or other flammable gases must be performed in a fume hood with strong ventilation.

Hydrogen Flammability and Explosion Hazard

All fuels have a unique flammable range, which is the minimum and maximum concentration in air necessary for combustion to occur. For combustion to occur, a fuel within its flammable range must also be exposed to an ignition source. Hydrogen’s flammability range (between 4% and 75% in air) is extensive compared to other fuels, as shown below.

Along with its wide flammability range, one safety concern with hydrogen is that it takes very little energy to ignite. Under the optimal combustion condition (a 29% hydrogen-to-air volume ratio), the energy required to initiate hydrogen combustion is much lower than that required for other common fuels (e.g., a small spark will ignite it), as shown. But at low concentrations of hydrogen in air, the energy required to initiate combustion is like that of other fuels.

The first line of defense against avoiding a fire or explosion is to prevent hydrogen from accidentally mixing with an oxidizer. Proper system and component design, installation, and maintenance can all help prevent leaks in hydrogen equipment. If a leak does occur, ventilation can act to dilute the hydrogen to keep the concentration below its lower flammable limit.

Buoyancy and Accumulation Hazard

Hydrogen’s small molecule size and low vapor density (14 times lighter than air) make it unique compared to many other fuels. It has high buoyancy and diffusivity, and as such, leaking hydrogen will rise and disperse quickly in air. This phenomenon is very different from

other common fuels, such as gasoline or propane. The vapors/gases from a release of these materials will pool near the ground.

Hydrogen’s ability to rise and disperse quickly can provide a safety advantage in an outside environment. However, in confined spaces, hydrogen can accumulate and reach a flammable concentration near high points, ceilings, and roofs. Proper ventilation and the use of hydrogen detection sensors are essential to mitigate this hazard.

Note: hydrogen’s molar mass is 2.016 g/mol. Dry air has a molar mass of 28.96 g/mol.

Experimental Results

Due to time constraints, our team performed abridged experiments to test the key functionalities of the device.

Our first test examined the ability of the sensor and amplifier circuit on the PCB to measure the concentration of H₂ gas. The first test was a qualitative burst of pure H₂ directly into the sensor. The capsule was immediately removed from the H₂ environment, and as such, the sensor reading immediately dropped back down to the baseline voltage reading (~950mV).

During the second test, the capsule was placed inside of the chamber, and 20mL of pure H₂ gas was injected into a chamber with a volume of approximately 500mL. This setup was calculated to have a H₂ concentration of 4% after injection. The sensor detected an increase of approximately 700mV, to an average value of 1630mV. The PCB was designed to output a maximum voltage of 3700mV at the sensor saturation point (5% H₂ concentration). Since the baseline voltage is approximately 950mV, the voltage increase indicated that the sensor detected a concentration of approximately 25%. We hypothesized that the higher than expected H₂ concentration was due to uneven distribution of H₂ inside the vessel: the device was placed near the top of the chamber, and H₂ gas is known to rise above other heavier gasses.

All of the data generated in this experiment was transmitted wirelessly to a computer located approximately 3 feet away, validating the wireless communicability of the capsule.

The results of this experiment indicate the H₂ sensor and amplification circuit are likely working as expected, as the sensor data read by the MCU is consistent with the H₂ concentration that we would expect to see in the experimental setup described.

Our second preliminary experiment tested the ability of the device to retain the phage therapy inside of the capsule prior to a drug release activation signal, and then the ability to release the therapy on demand when drug release is required. For the initial test, we used a blue dye as a phage substitute, as the leakage of a liquid out of the capsule before and after activation was the only variable of interest in this experiment.

We found that approximately 35% of the dye solution contained inside of the capsule leaked to the surroundings, without any noticeable disengagement between the cap and the main capsule body. This leakage increased to approximately 55% when the capsule was agitated (to simulate normal GI tract conditions), but there was still no obvious cap detachment.

When the release mechanism was triggered, there was an immediate noticeable separation between the main capsule and cap, releasing the entirety of the simulated phage therapy into the surroundings. These findings indicate that while additional iteration is required to ensure waterproofing at the barrier between the cap and main capsule, the primary release mechanism to expel the phage therapy from the pill is functioning as intended.

Conclusion/Future Work

At the time of writing this wiki, we have demonstrated a simple proof of concept of EVADE. In the coming weeks, we will be continuing with our experimentation and iterative processes to further improve the device and do testing with bacterial cultures.

We hope that our device can be used as a stepping stone to pave the way for future consumable electromechanical devices with a targeted release, increasing the customizability and targetability of treatments.