XML 47 R35.htm IDEA: XBRL DOCUMENT
v3.25.2

COMMON STOCK, PREFERRED STOCK AND WARRANTS - 2024 Public Offering (Details) - USD ($) $ / shares in Units, $ in Thousands |  |  | 3 Months Ended | 6 Months Ended |  |
--- | --- | --- | --- | --- | --- | ---
Jun. 06, 2025 | May 09, 2024 | Jun. 30, 2025 | Jun. 30, 2024 | Jun. 30, 2025 | Jun. 30, 2024 | Dec. 31, 2024 | May 31, 2024
COMMON STOCK, PREFERRED STOCK AND WARRANTS |  |  |  |  |  |  |  |
Fair value of derivative liability |  |  |  |  |  |  | $ 241 |
Change in fair value of derivative liability |  |  |  |  | $ 5,919 | $ (2,875) |  |
Share issuance costs |  |  |  |  | $ 1,212 | $ 850 |  |
Repayment of promissory notes | $ 1,560 |  |  |  |  |  |  |
Common stock, par value (in dollars per share) |  |  | $ 0.001 |  | $ 0.001 |  | $ 0.001 |
Pre-funded Warrants |  |  |  |  |  |  |  |
COMMON STOCK, PREFERRED STOCK AND WARRANTS |  |  |  |  |  |  |  |
Number of warrants exercised |  |  | 16 |  | 16 |  |  |
Common Stock |  |  |  |  |  |  |  |
COMMON STOCK, PREFERRED STOCK AND WARRANTS |  |  |  |  |  |  |  |
Shares issued |  |  | 54,001 | 939 | 54,125 | 1,136 |  |
2024 Public Offering |  |  |  |  |  |  |  |
COMMON STOCK, PREFERRED STOCK AND WARRANTS |  |  |  |  |  |  |  |
Combined offering price (in dollars per share) |  | $ 1,687.5 |  |  |  |  |  | $ 1,687.5
Offering price per Pre-funded warrant and accompanying Public Warrants (in dollars per share) |  | $ 1,687.499 |  |  |  |  |  | $ 1,687.499
Net proceeds from issuance of common stock |  | $ 5,500 |  |  |  |  |  |
2024 Public Offering | Public Warrants |  |  |  |  |  |  |  |
COMMON STOCK, PREFERRED STOCK AND WARRANTS |  |  |  |  |  |  |  |
Exercise price |  | $ 1,687.5 |  |  |  |  |  |
2024 Public Offering | Series A Warrants |  |  |  |  |  |  |  |
COMMON STOCK, PREFERRED STOCK AND WARRANTS |  |  |  |  |  |  |  |
Shares of common stock purchasable with warrants |  | 3,802 |  |  |  |  |  |
Warrant expiration period |  | 12 months |  |  |  |  |  |
2024 Public Offering | Series B Warrants |  |  |  |  |  |  |  |
COMMON STOCK, PREFERRED STOCK AND WARRANTS |  |  |  |  |  |  |  |
Shares of common stock purchasable with warrants |  | 3,802 |  |  |  |  |  |
Warrant expiration period |  | 5 years |  |  |  |  |  |
2024 Public Offering | Pre-funded Warrants |  |  |  |  |  |  |  |
COMMON STOCK, PREFERRED STOCK AND WARRANTS |  |  |  |  |  |  |  |
Shares of common stock purchasable with warrants |  | 2,859 |  |  |  |  |  | 2,859
Exercise price |  | $ 0.001 |  |  |  |  |  | $ 0.001
Number of warrants exercised |  | 1,435 |  |  |  |  |  |
Number of warrants outstanding |  |  | 0 |  | 0 |  |  |
2024 Public Offering | Common Stock |  |  |  |  |  |  |  |
COMMON STOCK, PREFERRED STOCK AND WARRANTS |  |  |  |  |  |  |  |
Shares issued |  | 939 |  |  |  |  |  |

X
- Definition Class of warrant or right exercised. + References No definition available. + Details
Name: | hsdt_ClassOfWarrantOrRightExercised
Namespace Prefix: | hsdt_
Data Type: | xbrli:sharesItemType
Balance Type: | na
Period Type: | duration

X
- Definition The cash flow impact of the amount of increase (decrease) in the fair value of derivatives. + References No definition available. + Details
Name: | hsdt_DerivativeGainLossOnDerivativeNetCashFlowImpact
Namespace Prefix: | hsdt_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition Proceeds from issuance of common stock, net. + References No definition available. + Details
Name: | hsdt_ProceedsFromIssuanceOfCommonStockNet
Namespace Prefix: | hsdt_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition The combined offering price per share in a sale of stock transaction. + References No definition available. + Details
Name: | hsdt_SaleOfStockCombinedOfferingPricePerShare
Namespace Prefix: | hsdt_
Data Type: | dtr-types:perShareItemType
Balance Type: | na
Period Type: | instant

X
- Definition The offering price per share per the Pre-funded warrants and accompanying Public Warrants. + References No definition available. + Details
Name: | hsdt_SaleOfStockPreFundedWarrantsAndAccompanyingPublicWarrantsPricePerShare
Namespace Prefix: | hsdt_
Data Type: | dtr-types:perShareItemType
Balance Type: | na
Period Type: | instant

X
- Definition Schedule of stockholders equity. + References No definition available. + Details
Name: | hsdt_ScheduleOfStockholdersEquityLineItems
Namespace Prefix: | hsdt_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition Exercise price per share or per unit of warrants or rights outstanding. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Topic 505 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 3 -Publisher FASB -URI https://asc.fasb.org/1943274/2147481112/505-10-50-3 + Details
Name: | us-gaap_ClassOfWarrantOrRightExercisePriceOfWarrantsOrRights1
Namespace Prefix: | us-gaap_
Data Type: | dtr-types:perShareItemType
Balance Type: | na
Period Type: | instant

X
- Definition Number of securities into which the class of warrant or right may be converted. For example, but not limited to, 500,000 warrants may be converted into 1,000,000 shares. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Topic 505 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 3 -Publisher FASB -URI https://asc.fasb.org/1943274/2147481112/505-10-50-3 + Details
Name: | us-gaap_ClassOfWarrantOrRightNumberOfSecuritiesCalledByWarrantsOrRights
Namespace Prefix: | us-gaap_
Data Type: | xbrli:sharesItemType
Balance Type: | na
Period Type: | instant

X
- Definition Number of warrants or rights outstanding. + References No definition available. + Details
Name: | us-gaap_ClassOfWarrantOrRightOutstanding
Namespace Prefix: | us-gaap_
Data Type: | xbrli:sharesItemType
Balance Type: | na
Period Type: | instant

X
- Definition Face amount or stated value per share of common stock. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Topic 210 -SubTopic 10 -Name Accounting Standards Codification -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02(29)) -Publisher FASB -URI https://asc.fasb.org/1943274/2147480566/210-10-S99-1 + Details
Name: | us-gaap_CommonStockParOrStatedValuePerShare
Namespace Prefix: | us-gaap_
Data Type: | dtr-types:perShareItemType
Balance Type: | na
Period Type: | instant

X
- Definition Fair value, after the effects of master netting arrangements, of a financial liability or contract with one or more underlyings, notional amount or payment provision or both, and the contract can be net settled by means outside the contract or delivery of an asset, expected to be settled after one year or the normal operating cycle, if longer. Includes assets not subject to a master netting arrangement and not elected to be offset. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Topic 210 -SubTopic 20 -Name Accounting Standards Codification -Section 50 -Paragraph 3 -Subparagraph (c) -Publisher FASB -URI https://asc.fasb.org/1943274/2147483466/210-20-50-3 + Details
Name: | us-gaap_DerivativeLiabilitiesNoncurrent
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition The cash outflow for cost incurred directly with the issuance of an equity security. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Name Accounting Standards Codification -Topic 230 -SubTopic 10 -Section 45 -Paragraph 15 -Publisher FASB -URI https://asc.fasb.org/1943274/2147482740/230-10-45-15 + Details
Name: | us-gaap_PaymentsOfStockIssuanceCosts
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition Amount of cash outflow for short-term and long-term debt. Excludes payment of lease obligation. + References Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef -Topic 230 -SubTopic 10 -Name Accounting Standards Codification -Section 45 -Paragraph 15 -Subparagraph (b) -Publisher FASB -URI https://asc.fasb.org/1943274/2147482740/230-10-45-15 + Details
Name: | us-gaap_RepaymentsOfDebt
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition Number of new stock issued during the period. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Name Accounting Standards Codification -Section 50 -Paragraph 2 -SubTopic 10 -Topic 505 -Publisher FASB -URI https://asc.fasb.org/1943274/2147481112/505-10-50-2 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Topic 210 -SubTopic 10 -Name Accounting Standards Codification -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02(28)) -Publisher FASB -URI https://asc.fasb.org/1943274/2147480566/210-10-S99-1 Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef -Topic 210 -SubTopic 10 -Name Accounting Standards Codification -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02(29)) -Publisher FASB -URI https://asc.fasb.org/1943274/2147480566/210-10-S99-1 Reference 4: http://www.xbrl.org/2003/role/disclosureRef -Topic 946 -SubTopic 505 -Name Accounting Standards Codification -Section 50 -Paragraph 2 -Subparagraph (a) -Publisher FASB -URI https://asc.fasb.org/1943274/2147478448/946-505-50-2 Reference 5: http://www.xbrl.org/2003/role/disclosureRef -Topic 946 -SubTopic 220 -Name Accounting Standards Codification -Section S99 -Paragraph 3 -Subparagraph (SX 210.6-09(4)(b)) -Publisher FASB -URI https://asc.fasb.org/1943274/2147479134/946-220-S99-3 Reference 6: http://www.xbrl.org/2003/role/disclosureRef -Topic 946 -SubTopic 10 -Name Accounting Standards Codification -Section S99 -Paragraph 3 -Subparagraph (SX 210.6-03(i)(1)) -Publisher FASB -URI https://asc.fasb.org/1943274/2147479886/946-10-S99-3 Reference 7: http://fasb.org/us-gaap/role/ref/legacyRef -Topic 505 -SubTopic 10 -Name Accounting Standards Codification -Section S99 -Paragraph 1 -Subparagraph (SX 210.3-04) -Publisher FASB -URI https://asc.fasb.org/1943274/2147480008/505-10-S99-1 + Details
Name: | us-gaap_StockIssuedDuringPeriodSharesNewIssues
Namespace Prefix: | us-gaap_
Data Type: | xbrli:sharesItemType
Balance Type: | na
Period Type: | duration

X
- Definition Period between issuance and expiration of outstanding warrant and right embodying unconditional obligation requiring redemption by transferring asset at specified or determinable date or upon event certain to occur, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents reported fact of one year, five months, and thirteen days. + References Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef -Topic 820 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 2 -Subparagraph (bbb)(2)(i) -Publisher FASB -URI https://asc.fasb.org/1943274/2147482106/820-10-50-2 Reference 2: http://www.xbrl.org/2009/role/commonPracticeRef -Topic 820 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 2 -Subparagraph (bbb)(2) -Publisher FASB -URI https://asc.fasb.org/1943274/2147482106/820-10-50-2 Reference 3: http://www.xbrl.org/2009/role/commonPracticeRef -Topic 820 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 2 -Subparagraph (bbb)(1) -Publisher FASB -URI https://asc.fasb.org/1943274/2147482106/820-10-50-2 + Details
Name: | us-gaap_WarrantsAndRightsOutstandingTerm
Namespace Prefix: | us-gaap_
Data Type: | xbrli:durationItemType
Balance Type: | na
Period Type: | instant

X
- Details
Name: | us-gaap_ClassOfWarrantOrRightAxis=hsdt_PreFundedWarrantsMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_StatementEquityComponentsAxis=us-gaap_CommonStockMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_SubsidiarySaleOfStockAxis=hsdt_PublicOffering2024Member
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_ClassOfWarrantOrRightAxis=hsdt_PublicWarrantsMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_ClassOfWarrantOrRightAxis=hsdt_SeriesWarrantsMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_ClassOfWarrantOrRightAxis=hsdt_SeriesBWarrantsMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |