Ear-Zapping device aims to keep opioid users on track

Copied word for word from the study's registry entry, so the wording is the study team's rather than ours.

Inclusion Criteria: * Aged 18-65. * Patient seeking buprenorphine therapy (BUP) for opioid use disorder and able to be randomized within 28 calendar days of induction on BUP. * Meets Diagnostic and Statistical Manual - 5 (DSM-5) diagnostic criteria for moderate to severe opioid use disorder with induction on buprenorphine. This includes volunteers who have taken buprenorphine in the past and are re-starting, are currently receiving non-buprenorphine medication for opioid use disorder, or have taken non-buprenorphine medication for opioid use disorder in the past and are transitioning to buprenorphine therapy for the first time. * Meets DSM-5 diagnostic criteria for posttraumatic stress disorder (PTSD). * Is able to understand the study, and having understood, provide written informed consent in English. * Provides permission to extract data from the participant's electronic medical record. Exclusion Criteria: * Unable to provide sufficient contact information (must provide at least two reliable indicators). * Volunteers who will not undergo induction on BUP within the eligibility window for randomization. * Volunteers who intend to, or will receive, inpatient substance use disorder (SUD) care at the time of randomization. Volunteers receiving inpatient detoxification care at the time of screening or baseline assessment are eligible if they will no longer be receiving inpatient care when they would be randomized for the study. * Volunteers actively participating in evidence-based psychotherapy for PTSD (e.g., Prolonged Exposure, Cognitive Processing Therapy, etc.). * Volunteers who will not have been stable on medications that affect PTSD (i.e., sertraline, paroxetine, venlafaxine, prazosin, or trazodone) for at least four weeks before they could be randomized. * Volunteer presents current evidence of an uncontrolled and/or clinically significant medical or psychiatric condition that will impact their ability to comply with the study requirements or would make their study participation unsafe. This includes unmedicated bipolar disorder with a manic episode in the past month or unmedicated psychotic disorder. * Volunteer has a history of epileptic seizure. * Volunteer has a history of neurological disorder or traumatic brain injury with significant lasting effects (e.g., memory problems, emotional changes, behavioral changes). * Volunteer had a suicide attempt leading to hospital admission in the past month or suicidal ideation with a plan and intent to act upon it in the past month. * Volunteer has the presence of devices (e.g., pacemakers, cochlear prosthesis, neurostimulators). * Volunteer has abnormal ear anatomy or an ear infection is present. * Volunteer is pregnant or lactating. * Volunteers of childbearing potential, not using adequate contraception as per investigator judgment or not willing to comply with contraception for the duration of the study's active participation period (i.e., 12 weeks following randomization). * Volunteer has any other significant medical or psychosocial problems that, in the opinion of the investigator, would potentially cause harm to the participant, impact their ability to participate, or influence the results of the project's trial. These include circumstances such as impending incarceration, moving out of the area, or a general history of noncompliance.