## 2 Patients and Methods  
### Patients  
The study cohort included 22 children with ADHD, all of whom were examined by a pediatric neurologist or psychiat and were asked to sit on the smart chair for data to be recorded. All of them visited our department in the morning. Children with a history of epilepsy, intellectual disability, drug abuse, head injury, or psychotic disorders were excluded. An ADHD diagnosis was made according to the Diagnostic and Statistical Manual of Mental Disorders (DSM)-5 criteria, and ADHD severity was evaluated usingthe SNAP-IV. The 26 items of the SNAP-IV include the 18 ADHD symptoms (9 related to inattentiveness and 9 related to hyperactivity/impulsiveness) and the 8 opposition defiant disorder symptoms specified in the DSM-IV. Items are rated on a four-point scale from 0 (_not at all_) to 3 (_very much_). The SNAP-IV is one of the most used instruments for measuring ADHD symptom severity [32,33]. It is composed of all the key symptoms for ADHD and oppositional defiant disorder (ODD) as described in the Diagnostic and Statistical Manual of Mental Disorders, 4 th ed. (DSM-IV) [5]. Studies including school- and clinical-based samples from multiple countries have shown good test-retest reliability and high internal consistency for the parent and/or teacher forms of the SNAP-IV [32,34,35,36]. ADHD is diagnosed based on the patient's symptoms into one of three subtypes: inattentive (ADHD-I; inattentive symptoms and few or no hyperactive symptoms), hyperactive/impulsive (ADHD-H; hyperactive or impulsive symptoms and few or no inattentive symptoms), or combined (ADHD-C; both inattentive and hyperactive symptoms) ADHD. In the present study, we enrolled 22 patients (18 boys and 4 girls). The mean age of patients was 8 years and 4 months \(\pm\)2 years and 6 months. All 18 boys had ADHD-C; two girls had ADHD-C, and two girls had ADHD-I. Written informed consent was obtained from a family member or legal guardian of each participant. This study was approved by the Institutional Review Board of Kaohsiung Medical University Hospital (KMUIRB-SV(I)- 20190060). This study used the smart chair, which was connected to a recording device, to assist in the measuring therapeutic effects of ADHD (Figure 1). The piezoelectric material was installed in the chair cushion. A piezoelectric material is a dielectric material that transforms mechanical stress into electrical charge. When mechanical stress is applied to the piezoelectric material, the piezoelectric material simultaneously generates an equal amount of charge on its surface. The positive and negative charges on the surface of the material gradually neutralize, and the potential eventually decays to zero. The material must be repeatedly stretched and compressed for electricity to be continuously generated. A ceramic piezoelectric material was used in this study, and the piezoelectric voltage constant was approximately 300 pC/N. The recorder sampled the signal at a sampling rate of 150 s/s, the voltage range was \(\pm\)7 mV, and the digital signal was stored at a 12-bit resolution format. The recorder was powered by a battery and could record data continuously for more than 10 h. To ensure precise analysis for each patient, we excluded the signals indicating when the patient initially sat down, finally stood up, or moved while not sitting on the chair. In this study, a piezoelectric material was inserted into a medical chair, and the chair's outward appearance was unchanged. We then used this chair to measure the movements of patients with ADHD to analyze the therapeutic effect of ADHD medication (Figure 1). Figure 1: Architecture of the detection system. When the patients visited a doctor, they sat on the medical chair. During the appointment, the patients' movements were recorded before being analyzed. An inherent problem with this system was noise, which interfered with the signal during transmission and resulted in signal distortion. Such noise meant that signals for an empty chair were at a nonzero level.