Table 3.

Bill of materials summary.

Component	Number	Cost per unit (USD)	Total cost (USD)	Source of materials
Main Board1	1	22.99	22.99
Silver-Woven Fabric Electrode	4	1.37	5.48	https://item.taobao.com/item.htm?spm=a1z09.2.0.0.44c02e8dvqfw3q&id=677903683078&_u=333r9ooifb7c
Ear Electrode Clamp	1	8.23	8.23	https://item.taobao.com/item.htm?spm=a1z09.2.0.0.44c02e8dvqfw3q&id=561114449471&_u=333r9ooi3b0f
ECG Lead Wire	4	2.06	8.24	https://item.taobao.com/item.htm?spm=a1z09.2.0.0.44c02e8dod1DNZ&id=654892666581&_u=333r9ooi9e4b
3.5 mm 4P audio Plug	2	0.27	0.54	https://item.taobao.com/item.htm?spm=a1z09.2.0.0.44c02e8dvqfw3q&id=672376474562&_u=333r9ooic0b4
VR Holder2	1	12.75	12.75	https://item.taobao.com/item.htm?spm=a1z09.2.0.0.44c02e8d6goQc4&id=660487198909&_u=333r9ooi9789
M2 Bolt (M2*4 + 3)	8	0.011	0.088	https://detail.tmall.com/item.htm?_u=333r9ooid60b&id=723347838083&spm=a1z09.2.0.0.44c02e8d6goQc4
M2 Nut	4	0.044	0.176	https://detail.tmall.com/item.htm?_u=333r9ooi915e&id=612966794798&spm=a1z09.2.0.0.44c02e8d6goQc4&skuId=4315124529170
Lithium-ion Battery (250mAh 3.7 V)	1	1.75	1.75	https://item.taobao.com/item.htm?spm=a1z09.2.0.0.44c02e8dvqfw3q&id=528235852444&_u=333r9ooi8732

1. The complete BOM of the mainboard can be found in the attached BOM file

2. In addition to the aforementioned components, a VR device is also required. The VR holder in Table 3 supports Oculus Quest 2, and if other VR devices are used, the VR holder can be replaced accordingly.

3. The cost does not include PCB manufacturing and SMT expenses