TissueDB/Simulators/Thermal Ablation Simulator

Thermal ablation of cervical pre-cancer lesions is part of cervical cancer screening and treatment in primary health care facilities and mobile units in resource-constrained settings. This low-cost simulator allows nurses, midwives, clinical officers, and medical officers to develop confidence and competence in performing the procedure. Medical Makers modelled the simulator on the Liger Medical HTU-110 Thermocoagulator. It contains five components: (1) probe shaft with heating tip (including hot and cold probes of different probe tip diameters), (2) smartphone light to visualize the cervix, (3) mobile app-based user interface, (4) handle, and (5) augmented feedback circuit to alert the user if the heated probe touches the vaginal sidewalls of the companion Cervical Cancer Screening Simulator.

This instrument simulator is a companion device to the Cervical Cancer Screening Simulator. It does not contain tissue-simulating materials itself; rather, the probe tips interact with the clay cervix models in the companion simulator. The augmented feedback circuit uses aluminum foil on both devices to create a closed electrical circuit that triggers a buzzer when the probe contacts the vaginal canal lining, alerting the learner to incorrect probe positioning. This simulator was developed as part of the Sexual and Reproductive Health and Rights (STARS) – Cervical Cancer Screening and Treatment training module.^[1] Probe dimensions match the Liger Medical HTU-110 product specifications.

Step 1: Cut out the base shape (rectangle with three tabs) from corrugated cardboard as shown in the template pattern.

Step 2: Measure and cut a 4.0 cm slot that aligns with the tab on the far right of the base piece.

Step 3: Roll the cardboard into a cylinder and insert the tab into the slot to form the handle.

Step 4: Secure the base cylinder with tape.

Step 1: Cut out the body piece from corrugated cardboard following the template pattern.

Step 2: Create three holes of 1.0 cm diameter and one horizontal slot in the center of the body as shown. The three holes accommodate the probe, phone light, and feedback wire.

Step 3: Use a toothpick to make two pairs of small holes in the body on the shaded section for elastic mounting.

Step 4: Loop one elastic band through each pair of small holes from the back of the body.

Step 5: Use a ruler to make straight folds at the four measured sections (indicated by horizontal fold lines).

Step 6: Fold the body into an uppercase M-shape. The three 1.0 cm holes should align when folded. Insert the tab into the slot.

Step 7: On the section with no holes, center the base and mark its position.

Step 8: Remove the tab from the slot. Cut out the two curved marks where the base will insert.

Step 9: Insert the base into the cut-out marks on the body. Re-insert the tab into the slot.

Step 10: Tape the folded and layered cardboard sections together to secure the body structure.

Step 1: Cut a 3.0 cm × 23.0 cm rectangle from corrugated cardboard.

Step 2: Roll the rectangle into a 1.0 cm diameter, 23.0 cm long cylinder.

Step 3: Secure the shaft with tape along its length. Repeat Steps 1–3 three more times to make a total of four probe shafts.

Step 1: Cut cardboard in the probe tip shape as shown. The 5.0 cm length of the taller rectangle provides the circumference for the 16.0 mm diameter tip.

Step 2: Tape the thinner end of the cardboard strip firmly to a probe shaft.

Step 3: Wrap the strip around the probe shaft while taping perpendicular to secure.

Step 4: When the taller portion is reached, place and fold a long piece of tape over the top of the probe tip. This prevents the tip from sticking to the clay cervix model.

Step 5: Align and tape together the edges of the 5.0 cm rectangle to create a circular tip with 16.0 mm outer diameter. Continue wrapping and securing to the shaft.

Step 6: Verify the probe tip outer diameter measures 16.0 mm using a ruler.

Step 1: Cut cardboard in the probe tip shape. The 6.0 cm length of the taller rectangle provides the circumference for the 19.0 mm diameter tip.

Step 2: Tape the thinner end to a second probe shaft.

Step 3: Wrap and tape the strip around the shaft.

Step 4: Cover the top of the probe tip with tape to prevent sticking to clay.

Step 5: Align and tape the 6.0 cm rectangle edges to create a 19.0 mm outer diameter circular tip.

Step 6: Verify the tip measures 19.0 mm using a ruler.

Step 1: For each cold probe, cut a 7.0 cm × 30.0 cm rectangle of aluminum foil.

Step 2: Align the foil edge to the edge of the cold probe tip. Tape the foil to the tip using loops of tape (sticky side out). Do not cover the flat top surface with foil. Do not cover the foil with tape on the outside — tape insulates and breaks the circuit.

Step 3: Secure the loose foil on the probe tip.

Step 4: Wrap the remaining foil around the probe shaft, leaving approximately 3.0 cm uncovered (foil-free) at the insertion end of the shaft.

Step 1: Cut cardboard in the probe tip shape. The 6.0 cm rectangle provides circumference for 19.0 mm diameter.

Step 2: Tape the thinner end to a third probe shaft.

Step 3: Wrap and tape the strip around the shaft.

Step 4: Align and tape the rectangle edges to create a 19.0 mm outer diameter tip.

Step 5: Verify the tip measures 19.0 mm using a ruler.

Step 1: Cut cardboard in the probe tip shape. The 8.0 cm rectangle provides circumference for 25.0 mm diameter.

Step 2: Tape the thinner end to the fourth probe shaft.

Step 3: Wrap and tape the strip around the shaft.

Step 4: Align and tape the 8.0 cm rectangle edges to create a 25.0 mm outer diameter tip.

Step 5: Verify the tip measures 25.0 mm using a ruler.

Step 1: For each hot probe, cut a 9.0 cm × 30.0 cm rectangle of aluminum foil.

Step 2: Place the probe tip and shaft approximately 5.0 cm down from the edge of the foil.

Step 3: Wrap the foil gently over the tip while pressing down on the probe tip outline. The tip outline should project slightly from the foil surface to leave an impression of the treated area on the clay cervix model.

Step 4: Wrap the remaining foil around the probe shaft, leaving approximately 3.0 cm uncovered (foil-free) at the insertion end.

Step 1: Measure and mark 5.0 cm from the bottom edge of the simulator body.

Step 2: Place the cellphone in the center of the simulator. Position a toothpick next to the phone at the 5.0 cm mark.

Step 3: Use the toothpick to puncture through the body at a 45-degree angle to emerge next to the base. Repeat on the opposite side with a second toothpick.

Step 4: Slide the cellphone into the elastics, starting with the lower elastic.

Step 5: Wrap the bottom elastic around the toothpicks until the phone is tightly secured in place.

Step 6: Insert the desired probe shaft into the 1.0 cm hole in the front of the simulator.

The augmented feedback circuit alerts the learner when the probe tip contacts the vaginal sidewall of the companion Cervical Cancer Screening Simulator. The circuit works by completing an electrical loop: aluminum foil on the probe shaft connects through alligator clips and wire to a 9V battery and buzzer, while the vaginal canal's aluminum foil lining connects to the other battery terminal. When the probe foil touches the canal foil, the circuit closes and the buzzer sounds.

Circuit Assembly:

Step 1: Form a loop of exposed wire from the black insulated end of the buzzer. Clip an alligator clip perpendicular to this wire loop. Connect this alligator clip to the negative lead of a 9V battery.

Step 2: Test the connection by attaching a second alligator clip from the red insulated end of the buzzer to the positive battery lead. The buzzer should sound. Disconnect the second clip after verification.

Step 3: Connect the second alligator clip (from the red buzzer wire) to the exposed aluminum foil of the vaginal canal on the companion Cervical Cancer Screening Simulator.

Step 4: Cut a small length of wire. Loop and twist both ends around the aluminum foil on the proximal probe shaft. Attach one alligator clip to this wire loop. Wind the clip down and around the simulator handle, securing with tape. Attach a second alligator clip to the free end.

Step 5: Connect the alligator clip from the probe to the remaining battery lead. Wear gloves to prevent completing the circuit through skin contact. Test by touching the probe tip to the vaginal canal foil — the buzzer should sound.

The Thermocoagulator Simulator mobile app simulates the Liger Medical HTU-110 user interface, light illumination feature, and sounds heard during thermal ablation. The app also directs users to take pre- and post-treatment photos of the cervix using the cellphone camera.

Requirements: Android smartphone with internet connection for initial download.

Installation:

Step 1: Open the Google Play Store application.

Step 2: Search for "Thermocoagulator Simulator" in the search bar.

Step 3: Select the app displaying the Medical Makers logo as the icon.

Step 4: Press Install to download and install the app.

Step 5: Press the app icon to open when ready for use.

Developer: Jude Barnabas (Ugandan Medical Maker). Built with MIT App Inventor.

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