Depreciation and Amortization. Depreciation and amortization expense for the six months ended June 30, 2020 was $1,289,253 as compared to $1,167,054 in the same period in 2019, an increase of $122,199. The increase in depreciation expense is due to new investments in depreciable assets, including manufacturing equipment and molds placed into service from construction-in-progress and leasehold improvements associated with our plant expansion which were completed in the first quarter of 2019.
Other Income (Expense). Total other expense, net was $23,173 for the six months ended June 30, 2020 as compared to income of $3,365 in the period in 2019. The overall increase of $26,538 in other expenses was primarily the result of a decrease of $61,806 in investment interest income; partially offset by a decrease of $35,898 in other taxes.
Provision for Income Taxes. There was not a provision for income taxes in the respective six-month periods ending June 30, 2020 and 2019.
Liquidity and Capital Resources
As of June 30, 2020, we had cash and cash equivalents of $13,229,182, an increase of $2,623,091 from $10,606,091 as of December 31, 2019.
As of June 30, 2020, we had current assets of $22,923,268 as compared to current liabilities of $2,814,108 which resulted in a positive working capital position of $20,109,160. As of December 31, 2019, we had a working capital position of $16,438,851. Our current liabilities are comprised principally of accounts payable, operating lease liabilities and accrued expenses.
During the six months ended June 30, 2020, we used $8,871,081 of cash for operating activities which includes: (i) a net loss of $9,600,290, partially offset by non-cash expenses totaling $2,380,382 (ii) $923,257 expenditures in inventory and vendor prepayments for M400 components, (iii) $175,005 increase in accrued project revenue and (iv) $230,201 paydown of accounts payable that existed as of December 31, 2019. For the six months ended June 30, 2019, we used $11,683,121 of cash for operating activities.
For the three months ended June 30, 2020, net loss after adding back non-cash operating expenses was $2,871,558 versus $4,040,473 in the same period of 2019. The net loss after adding back non-cash operating expenses was $7,219,908 for the six months ended June 30, 2020 versus $9,326,391 for the same period of 2019.
During the six months ended June 30, 2020, we used $644,037 of cash for investing activities, which includes $253,174 for purchases of manufacturing equipment and product mold tooling and $250,000 in the purchase of software operating system upgrades for our smart glasses platform. For the six months ended June 30, 2019, we used $2,220,792 of cash for investing activities.
During the six months ended June 30, 2020, we received $12,138,209 in cash from financing activities, which included; (i) $10,582,309 in net proceeds from our sale of equity securities on May 12, 2020, and (ii) $1,555,900 in proceeds from the term loan obtained under the Payroll Protection Act. For the six months ended June 30, 2019, we did not incur any cash changes from financing activities.
As of June 30, 2020, the Company had $1,555,900 in current or long-term debt obligations outstanding. These debt obligations are to be repaid over an 18-month period beginning in November 2020. However, as discussed in Note 6, the Company intends to apply for forgiveness of this obligation.
We incurred a net loss for the six months ended June 30, 2020 of $9,600,290 and annual net losses of $26,476,370 in 2019 and $21,875,713 in 2018. As of June 30, 2020, the Company had an accumulated deficit of $154,343,101.
The Company needs to grow its business significantly to become profitable and self-sustaining on a cash flow basis or it will be required to raise new equity and/or debt capital. Our cash requirements related to funding operating losses depend upon numerous factors, including new product development activities, our ability to commercialize our